MINISTRY OF WORKS & HUMAN SETTLEMENT

ROYAL GOVERNMENT OF BHUTAN

MINISTRY OF WORKS & HUMAN SETTLEMENT

DEPARTMENT OF ROADS, REGIONAL OFFICE, SARPANG

CONSTRUCTION OF BARAREY BAILEY BRIDGE ON NICHULA GEWOG CENTRE

ROAD

TECHNICAL SPECIFICATIONS

&

PERFORMANCE REQUIREMENTS

TECHNICAL SPECIFICATION ABUTMENT OF BARAREY BRIDGE

Page | 1 of 112

INTRODUCTION

1. This Specification should be read in conjunction with the other documents which

are The Tender, the Conditions of Contract and, The Drawings.

3. This specification is split into Sections 1 to 4, which are identified on the

following pages. Each section is separated into specific sub sections with work

descriptions, specifications of materials, construction methods, methods of

measurement and items for payment.

4. This Technical Specification is an integral part of the contract and the Contractor

is required to comply fully with all aspects of this Specification.

5. The Contractor is responsible for ensuring that the necessary tests and

measurements are carried out in order to ensure that the work complies with the

Specifications. The Contractor shall give a minimum of 24 hours’ notice in

writing to the Engineer for each item of work to be covered or buried. The

contractor should make due allowance in his program of work for all necessary

testing of the works in accordance with these Specifications. Any work not

undertaken in accordance with these conditions may be rejected by the Engineer.

6. The term “Engineer” used in this specification and other sections of this tender

document shall mean a person with degree or diploma in engineering from any

recognized Institute or University of Engineering who shall supervise and be in

charge of the work, and act on behalf of the Employer/Client.


Page | 2 of 112

TECHNICAL SPECIFICATIONS

CONTENTS:

ABBREVIATIONS

SECTION 1 GENERAL AND SITE FACILITIES

SECTION 2 SITE CLEARANCE AND EARTH WORK

SECTION 3 STRUCTURES

SECTION 4 PERMANENT WORKS


Page | 3 of 112

ABBREVIATIONS

AASHTO AMERICAN ASSOCIATION OF STATE HIGHWAY AND

TRANSPORTATION OFFICIALS

ACV AGGREGATE CRUSHING VALUE

ASTM AMERICAN SOCIETY OF TESTING AND MATERIALS

BS BRITISH STANDARD

CBR CALIFORNIA BEARING RATIO

DOR DEPARTMENT OF ROADS

HWL HIGH WATER LEVEL

IS INDIAN STANDARD

LWL LOW WATER LEVEL

MLSS MEMBERS OF LOWER SERVICE STAFF

MSL MEAN SEA LEVEL

PVC POLYVINYL CHLORIDE

ROW RIGHT OF WAY

TS TECHNICAL SPECIFICATION

BoQ BILL OF QUANTITY IRC INDIAN ROAD CONGRESS


Page | 4 of 112

TABLE OF CONTENT

1.0 GENERAL AND SITE FACILITIES 10

1.1 GENERAL 11

1.1.1 Scope of Work 11

1.1.2 Site Acquaintance 11

1.1.3 Specifications 11

1.1.4 Reference to Bureau of Indian Standards Codes & Other Codes 11

1.1.5 Dimensions & Levels 11

1.1.6 Notice of operation 12

1.1.7 Work program 12

1.1.8 Time Schedule 12

1.1.9 Drawings 12

1.1.10 Sub-Contracting 12

1.1.11 Compliance 12

1.1.12 Supply of Materials 13

1.1.13 Ordering Materials 13

1.1.14 Material Quality 13

1.1.15 Equipment & Facilities 14

1.1.16 Work Site Register (Site Order Book) 14

1.1.17 Area for the Contractor 14

1.1.18 Unit of measurement 14

1.2 SITE INSTALLATION 15

1.2.1 Establishment of temporary infrastructure and facilities 15

1.2.1.1 Contractor’s site office 15

1.2.1.2 Labor Camps 16

1.2.1.3 Waste Management 16

1.2.1.4 Material Storage 16

1.2.1.5 Temporary Drainage System 16

1.2.1.6 Site Water Supply and Electricity 16

1.2.2 Additional facilities to be provided 17

1.2.2.1 Survey Equipment 17

1.2.2.2 Sign Boards 17

1.2.3 Testing of Materials 18

1.2.3.1 Contractor’s Site Laboratory 18

1.2.3.2 Materials Testing by Independent Laboratories 20


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1.2.3.3 Staff for Material Testing 20

1.2.3.4 Sampling and Testing 21

1.2.4 General Contractor’s Obligations 21

1.2.4.1 Insurance 21

1.2.4.2 Safety measures and penalties 21

1.2.4.3 Protection of the Environment 22

1.2.4.4 As-Built Drawings 22

1.2.5 Maintenance and demobilization 23

1.2.6 Measurement and Payment 23

1.2.7 Pay items shall be: 23

2.0 EARTH WORK 24

2.1 CLEARING AND GRUBBING 25

2.1.1 General 25

2.1.2 Clearing jungle 25

2.1.2.1 Measurements 26

2.1.2.2 Rates 26

2.1.3 Felling of Trees 26

2.1.3.1 Measurements 27

2.1.3.2 Rate 27

2.1.4 Pay Items 27

2.2 EXCAVATION AND BACKFILL FOR STRUCTURES 27

2.2.1 General 27

All kinds of soil 28

All kinds of rocks 28

2.2.1.1 Setting out 28

2.2.1.2 Stripping and storing topsoil 29

2.2.2 Excavation 29

2.2.2.1 Methods, tools and equipment 30

2.2.2.2 Rocks excavation: 30

2.2.2.3 Blasting 31

2.2.2.4 Disposal of Excavated Material 31

2.2.2.5 Cofferdams 32

2.2.2.6 Pumping and Bailing 32

2.2.3 Filling 33

2.2.3.1 Foundation Fill Material 33

2.2.3.2 Backfill Material 34

2.2.3.3 Backfilling 34

2.2.4 Plate Load Test on Foundations 35


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2.2.5 Measurements 36

2.2.6 Payment 37

2.2.7 Pay Items 37

3.0 STRUCTURES 38

3.1 CONCRETE FOR STRUCTURES 39

3.1.1 Standards 39

3.1.2 Description 39

3.1.3 Materials 40

3.1.3.1 Specifications for Materials 40

3.1.3.2 Testing of Materials 43

3.1.3.3 Composition of Concrete 45

3.1.3.4 Control of Concrete Quality 48

3.1.4 Construction Methods 52

3.1.4.1 General 52

3.1.4.2 Care and Storage of Concrete Materials 52

3.1.4.3 Preparations before Casting 53

3.1.4.4 Measuring Materials 53

3.1.4.5 Mixing Concrete 53

3.1.4.6 Handling and Placing Concrete 58

3.1.4.7 Perforations and Embedment of Special Devices 62

3.1.4.8 Finishing Concrete Surfaces 62

3.1.4.9 Construction Joints 64

3.1.4.10 Curing Concrete 65

3.1.4.11 Removal of Scaffolding and Formwork 65

3.1.4.12 Repair of Concrete 66

3.1.4.13 Depositing Concrete under Water 66

3.1.4.14 Factory Made Precast Concrete Elements 67

3.1.4.15 Control of Heat in Structures 68

3.1.4.16 Loading 68

3.1.4.17 Backfill to Structures 68

3.1.5 Measurement 69

3.1.6 Payment 69

3.1.7 Pay Items 69

3.2 FORMWORKS AND SCAFFOLDING 70

3.2.1 Scaffolding (Falsework) 70

3.2.2 Formwork 72

3.2.2.1 Surface Treatment for Shuttering 73

3.2.2.2 Camber 74


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3.2.3 Approval of Scaffolding and Formwork 74

3.2.4 Special Formwork 74

3.2.5 Removal of Form Work 75

3.2.6 Measurements 76

3.2.7 Payment 76

3.2.8 Pay Items 77

3.3 REINFORCEMENT 77


3.3.2 Materials 78

3.3.2.1 Bar Reinforcement 78

3.3.2.2 Wire Mesh 78

3.3.2.3 Binding Wire 78

3.3.2.4 Bar Sizes 78

3.3.2.5 Ordering Material 78

3.3.2.6 Additional Tests 79


3.3.3.1 Protection and Storage 79

3.3.3.2 Cutting and Bending 79

3.3.3.3 Placing, Supporting and Fastening 79

3.3.3.4 Splicing 80

3.3.3.5 Substitutions 80

3.3.4 Measurement 81

3.3.5 Payment 81

3.3.6 Pay Items 81

3.4 PRESTRESSING WORKS 82


3.4.2 Materials 82

3.4.2.1 Prestressing Cable/Tendon 82

3.4.2.2 Ordering Material 82


3.4.3.1 Protection and Storage 83

3.4.3.2 Placing, Positioning and Pre-stressing 83

3.4.3.3 Grouting 83

3.4.4 Inspection and Quality control 83

3.4.5 Payment 83

3.4.6 Pay Item 84

4.0 PERMANENT WORKS 85


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4.1 STONE MASONARY 86

4.1.1 Random Rubble Masonry 86

4.1.2 Dressing: 86

4.1.3 Laying: 86

4.1.4 Bond Stones: 87

4.1.5 Quoins or corner stone: 87

4.1.6 Jambs: 88

4.1.7 Joints: 88

4.1.8 Scaffolding: 88

4.1.9 Curing: 88

4.1.10 Protection: 88

4.1.11 Measurement: 88

4.2 STONE SOLING, FILLING& EDGING 89

4.2.1 Measurements: 89

4.2.2 Rate: 89

4.2.3 Cement Plaster 89

4.2.4 Preparation of surface: 89

4.2.5 Finish: 91

4.2.6 Precaution: 91

4.2.7 Thickness: 91

4.2.8 Curing: 91

4.2.9 Measurement: 92

4.2.10 Rate: 93


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LIST OF TABLES Table 2.2-1 Grading of foundation fill material ................................................................ 33

Table 3.1-1 Grading Requirements Coarse Aggregate .................................................... 42

Table 3.1-2 Grading Requirements for Fine Aggregate ................................................... 43

Table 3.1-3 Concrete classes ................................................................................................. 45

Table 3.2-1 Removal of Form Work .................................................................................... 75


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SECTION 1

1.0 GENERAL AND SITE FACILITIES


Page | 11 of 112

1.1 GENERAL

1.1.1 Scope of Work

The Scope of work covered by his specifications is to execute the construction of

RCC Girder Bridge at Tashithang on Punakha-Gasa Secondary National Highway.

1.1.2 Site Acquaintance

The Contractor shall be deemed to have made himself / herself fully acquainted

with the full nature of the work, the location & character of the bridge site & means

of access to the site, including any traffic restrictions imposed. The construction site

is an area within 5kms radius of the location of the bridge.

1.1.3 Specifications

The work shall be executed in accordance with the technical specifications, the

drawings, the Bill of Quantities & the instructions issued by the Client from time to

time. Wherever these specifications are found wanting in anyway, the latest edition

of standard specification for Bridges as approved by the Client shall be followed.

1.1.4 Reference to Bureau of Indian Standards Codes & Other Codes

The Standard Specifications & Codes of Practices explicitly referred to in these

Specifications or other related standard codes etc. shall be of latest editions, current

at the time of tendering including all amendments published before that date.

1.1.5 Dimensions & Levels

All dimensions & levels shown on the Drawings shall be verified by the Contractor

at the site & he/she will be held responsible for the accuracy & maintenance of all

dimensions & levels. Figured dimensions are in all cases to be accepted & no

dimensions shall be scaled. Large scale details shall take precedence over small scale

drawings. In case of discrepancy the Contractor shall ask for clarifications from the

Engineer before proceeding with the work.


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1.1.6 Notice of operation

The Contractor shall not carry out important operations without the consent in

writing of the Engineer.

1.1.7 Work program

The Contractor shall submit to the Engineer before commencement of the work, for

his approval, a detailed program in the form of bar chart/Microsoft project etc. The

submission & approval of such program shall not relieve the Contractor of any of his

duties or responsibilities under the Contract.

1.1.8 Time Schedule

The Contractor shall follow the project master schedule & detailed activity schedule

submitted after signing the contract. The contactor may submit minor changes on

schedule to the Engineer for approval whenever necessary.

1.1.9 Drawings

The Contractor will receive free of cost one complete set of all drawings necessary to

complete the Work & is to include in his Tender for any additional copies of

drawings required by him. One copy of the full set of drawings shall be retained at

the site.

1.1.10 Sub-Contracting

Should the Contactor consider it necessary to sub-contract any part of his work, the

Sub-Contractor & the scope of the work proposed to be sub contracted has to be

approved by the Engineer/Client. It will be the responsibility of the Contractor to

ensure that the sub-contracted works are carried out in accordance with the

specifications & relevant drawings.

1.1.11 Compliance

All workmanship, materials & tests (where required) shall comply with the

appropriate Indian or American Standards as specified or approved & be in

accordance with the drawings all to the satisfaction of the Client/Engineer.


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1.1.12 Supply of Materials

a. The Contractor shall supply certificates of compliance with specified Indian

Standards for all materials supplied for the works. Manufacturer’s catalogues &

samples of materials proposed for procurement & to be used in the works shall

be submitted to the Client for approval, before procurement.

b. Materials procured without specific approval of the Client shall not be allowed

to be used in the works.

c. The Contractor’s quoted rate shall include but not limited to:

i. Preparation & submission of shop drawings wherever necessary,

calculation sheets, schedule of materials, & providing catalogues about, &

samples of materials, & obtaining approval from the Client.

ii. Carryout of mix design, sampling and testing of construction materials,

preparation and testing of trial mixes, preparation and testing of concrete

test cubes, and obtaining approval from the Client.

iii. Transporting to the Site, including loading & unloading.

iv. Providing certificates of compliance with required relevant standards, as

specified.

v. Storing & protection of the materials at the Site.

1.1.13 Ordering Materials

The Contractor is entirely responsible for assessing the quantities of materials to be

ordered for use in the works.

1.1.14 Material Quality

The Contractor should note that the qualities of all materials used shall be

scrutinized, monitored & checked by the Client. All materials used have to fulfill the

requirements & specifications given in the drawings & in the relevant code of

practice. If the Contractor is asked to supply certificate of origin of the supplied &

used materials, he has to do so within a reasonable timeframe fixed by the Engineer.


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1.1.15 Equipment & Facilities

The Contractor shall provide & operate equipment & facilities to load, offload, shift,

move, transport, stack & place all types of steel parts & materials at the bridge site as

well as at the Contractor’s yard.

The Contractor shall also provide all lifting equipment & facilities to lift, shift, stack,

load, unload & handle all type of steel parts & materials at the bridge site as well as

at the Contractor’s yard.

1.1.16 Work Site Register (Site Order Book)

The Contractor shall keep a Work Site Register (Site Order Book) at the Site in which

all the remarks, instructions, decisions of the Client & the essential details of the

work shall be recorded. The Contractor shall keep the records of all daily

information of the works in this register as required by the Client. It shall be readily

available in the office for inspection.

1.1.17 Area for the Contractor

i. The Contractor shall be allocated an area for his equipment, materials & site

offices in the vicinity of the bridge site. If there are only private lands in the

vicinity of the bridge site, the Contractor has to arrange for the same at his own

cost.

ii. The Contractor shall maintain a properly furnished office, which will include

but not necessarily limited to lock up drawers for construction drawings, filing

cabinets, large sized soft board panels, etc., with toilet facility in the allocated

area at the site for his own use as well as for use of the Client & his

representatives. These shall be provided by the Contractor at no extra cost.

1.1.18 Unit of measurement

The following units of measurement & abbreviations shall be used.

Unit Abbreviation

Millimeter mm

Meter m

Square millimeter mm2

Square meter m2


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Hectare ha

Cubic metre m3

Kilogram kg

Tonne ton

Sum sum

Number no.

Hour hr

Week wk (7 days)

Pieces pcs

1.2 SITE INSTALLATION

1.2.1 Establishment of temporary infrastructure and facilities

As a part of the site installation, the contractor shall build and maintain all

temporary infrastructures such as contractor’s office, stores, workshops, Contractor's

yard, labor camp, access roads etc. for smooth implementation of the works.

The following facilities, but not limited to, shall be installed/built and maintained by

the contractor as a part of the site installation: -

1.2.1.1 Contractor’s site office

The contractor shall build and maintain a site office with sanitary facilities during

the project duration. The site office shall have a minimum plan area of 50m2 and

shall have at least CC flooring, bamboo mat or ekra wall and tin roof. The

contractor’s site office shall have minimum following facilities: -

i. Desk top computer set with sufficient capacity to run standard engineering

software such as AUTO CAD, LISCAD etc. - 1 no.

ii. A3 printer - 1 no.

iii. Photocopy Machine - 1 no.

iv. Scanner - 1 no.

v. Internet connection (subject to availability of the facility at the project site)

vi. Tables and chairs sufficient to conduct site meetings between the contractor

and the representatives of the Client


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1.2.1.2 Labor Camps

Labor camps with sufficient and maintained sanitary facilities, sufficient & safe

drinking water and sufficient supply of electric power have to be made available at

all times during the project duration.

The labor camps shall at least have CC flooring, bamboo mat wall and tin roof. The

size and number of such camps shall be approved by the Engineer based on the

labor strength requirement after contractor submits the master work plan

1.2.1.3 Waste Management

A proper waste management facility and system have to be put in place to maintain

general cleanliness of the site and upkeep hygiene of the personnel and laborers

working at the bridge site. The proposed facilities have to be approved by the

Engineer.

1.2.1.4 Material Storage

Construction materials have to be stored well under sheds to avoid quality drops

and loss.

Minimum following facilities have to be erected at the bridge site as a part of site

installation for material storage: -

i. Cement store – min. plan area 50m2, CC flooring, tin wall & roof (water tight

and limited air circulation) - 1 no.

ii. General store – min. plan area 25m2, CC flooring, bamboo mat/ekra wall and tin

roof - 1 no.

1.2.1.5 Temporary Drainage System

The Contractor shall build a temporary drainage system at the site to drain out waste

water. The layout and design of the drains have to be approved by the Engineer.

1.2.1.6 Site Water Supply and Electricity

The Contractor shall make his own connections for water and electric supply and

pay for them.


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The water supplied must be potable and must be free from salts, oils, acids, arsenic

and other substances harmful to health. The water shall be tested to confirm its

portability

If electricity is not available at the bridge site, the Contractor shall install generators

of sufficient number and capacity to power all the facilities at the bridge site such as

the Engineer’s Office, Contractor’s office, laboratory, labor camps, stores etc. If the

Contractor intends to use electrically operated construction equipment and

machinery, matching number and capacity of generators have to be installed at the

bridge site.

1.2.2 Additional facilities to be provided

As a part of the site installation, the contractor shall provide/build/install following

additional facilities: -

1.2.2.1 Survey Equipment

The Contractor will be required to provide survey equipment for the use of the

Contractor and Engineer and his staff. The equipment and all its accessories shall be

available at all times at the bridge site during the contract period and shall be

maintained in good working order. For higher accuracy and better ease of use, the

equipment shall be Total Station or equivalent. The contractor shall depute

appropriately qualified and trained personnel to operate the survey equipment at all

times during the contract period.

The survey equipment and its accessories (legs, reflectors and stands, rechargeable

batteries and charger etc.) shall be from any reputable manufacturer. The range,

accuracy, least count etc. of the equipment has to be approved by the Engineer.

1.2.2.2 Sign Boards

The Contractor shall provide identification sign boards and maintain them in good

condition. All information on the signboards will be written in English and

Dzongkha. The signboards will be positioned as directed by the Engineer.

Each sign shall show:

• the name of the Project

• the name of the Employer


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• name of the Contractor

• Contract start and completion dates

• Contract amount

• Any other details as required by the Engineer

Project Signboards shall have steel pipe posts of diameter from 75mm to 100mm

with 3mm thick steel plates. The steel pipe legs shall be embedded in the ground.

The design of the signpost and the information content on it shall be approved by

the Engineer.

The contractor shall install at least one sign board at the bridge site, the location of

which shall be approved by the Engineer.

The Contractor shall remove the sign boards on completion of the Works or when

instructed by the Engineer

1.2.3 Testing of Materials

1.2.3.1 Contractor’s Site Laboratory

The Contractor shall provide and maintain a Site Laboratory in a semi-permanent

building of about 25m2 plinth area with CC floor, bamboo mat wall & tin roof for the

use of the Contractor and the Engineer.

The laboratory shall have furniture, testing equipment and consumable stocks

necessary to carry out the tests listed below: -

1. Moisture Content

2. Particle Size Distribution

3. Standard Compaction

4. Flakiness Index

5. Fineness Modulus

6. Aggregate Crushing Value

7. Slump Test

8. Concrete Crushing Strength


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The Contractor would be required to mobilize, but not limited to, the following

equipment for quality assurance tests both at site and at the site laboratory as a part

of site installation:

1. Moisture can

2. Weighing balance (accuracy 0.01 gm)

3. 1000 ml glass cylinder with rubber bung

4. Graduated measuring cylinder

5. Hydrometer

6. Thermometer

7. Sample tray

8. Straight edge knife

9. Scoop

10. Mixing trowel

11. Sand pouring cylinder with lid

12. Metal tray

13. Flakiness index gauge

14. Sieve set

15. Slump cone

16. Scale

17. Concrete crushing machine

18. *Concrete cube mould

19. Tamping rod

20. Hand gloves & filter papers

21. Concrete thermometers

*The Contractor shall provide a sufficient number of cube moulds to meet the testing frequency

requirements for the concrete pour program for all the sites under the Contract. A reasonable number

of spare moulds should also be available for any ‘ad hoc’ testing that may be required.

The laboratory shall be housed inside a proper shelter. The layout, size and location

of the site laboratory have to be approved by the Engineer.


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The Contractor shall maintain the laboratory, furniture, fittings and testing

equipment for the duration of the Contract and replace any part or item that is

irreparably damaged or lost. The Contractor shall pay all expenses in respect of

water, electricity and other consumables necessary for the running of the laboratory

and shall arrange for the laboratory to be regularly cleaned.

The Contractor shall not be permitted to commence permanent works requiring on-

site testing till the Site laboratory is complete in all respects, unless temporary testing

procedures proposed by the Contractor have been approved by the Engineer.

At the end of the Contract, all materials recovered from dismantling the laboratory,

together with all furniture, fittings and testing equipment will remain the property

of the Contractor.

1.2.3.2 Materials Testing by Independent Laboratories

In addition to the above mentioned tests the Contractor shall arrange for the

following tests to be carried out at off-site testing facilities as and when instructed by

the engineer:

1. Tests on reinforcing steel

2. Tests on cement – fineness, setting time and strength

3. Aggregate crushing value

Other tests as may be decided by the Engineer

The Contractor shall be responsible for arranging off-Site laboratory tests, and all

other tests indicated as the responsibility of the Contractor in different Sections of

the Specifications. These tests shall be performed by off-site standard testing

laboratories proposed by the contractor and as approved by the Engineer. All the

expenses for such tests shall be borne by the contractor. The Contractor shall be

responsible for all attendance of staff from these approved testing laboratories,

including if necessary the provision of transport for personnel, equipment and test

specimens.

1.2.3.3 Staff for Material Testing

The Contractor shall provide qualified laboratory engineers, technicians, assistants,

laborers, etc. to carry out sampling and testing of materials in accordance with

Specifications Sections, 1.2.3.1. Laboratory staff shall be subject to the approval of the


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Engineer and be available to assist the Engineer with materials testing, as and when

required.

1.2.3.4 Sampling and Testing

For Concrete Mixes 1 set of tests per 100 m3 of aggregate for shape, grading, ACV /

10% Fines should be carried out.

The Contractor shall maintain complete records of test results, which may be

inspected by the Engineer at any time. All test results shall be recorded on standard

forms approved by the Engineer and shall be signed by the Contractor’s engineer or

technician in charge of the laboratory. Completed forms shall clearly show the

locations of samples, sampling dates and testing dates. Samples shall be numbered

serially at the time of sampling. A copy of all test results should be submitted to the

Engineer immediately after completion of the test.

The Engineer will be informed prior to any sampling or testing carried out in the

laboratory and will have the right to use the facilities and equipment to make his

own tests. The Contractor shall have the right to witness any sampling or testing

carried out by the Engineer. On completion of the Contract the original copies of all

test results shall be handed over to the Employer, via the Engineer.

1.2.4 General Contractor’s Obligations

1.2.4.1 Insurance

The contractor shall obtain all risk insurance for the work, plant, equipment,

personnel and labor. The modalities for the insurance shall be as per the stipulations

under Clause 14 of General Conditions of Contract (GCC).

1.2.4.2 Safety measures and penalties

The regulations and guidelines for Work Place Safety issued by Ministry of Labor

and Human Resources, RGoB shall be complied with at all times. The workers and

the personnel shall have safe and secure working conditions at the construction site

at all times and there shall be no compromise on the work place safety. The workers

shall wear safety gears – helmets, boots, belts, goggles, hand gloves, welding masks

etc. as may be appropriate, at the work site at all times.

The Contractor shall issue the required protective clothing and safety equipment to

all his employees and provide the first aid boxes within one month of the

commencement of the Contract. He is responsible for ensuring that all his employees


Page | 22 of 112

make appropriate use of the items and maintain them in good order. The Contractor

shall replace damaged, worn-out, exhausted or out of date items as necessary.

The Contractor shall build temporary scaffold, temporary stairs, working platforms,

fall-down-stoppers and such other measures to allow safe and proper execution and

check of the construction works. Anybody entering the worksite shall wear safety

helmets at all times. If scaffold, working platforms etc. are not possible or not

required, the personnel and the workers have to wear safety belts. The quality of the

safety belts has to be approved by the Engineer.

If any worker is found at the worksite without appropriate safety equipment/gear,

the Contractor shall be subject to a penalty of Nu. 300 per instance. The penalty

amount shall be deducted from the payments for the work due to the Contractor.

The Contractor has to bear the penalty himself and shall not recover the same from

the worker. The photograph of the worker at the worksite without the appropriate

safety gear shall be adequate enough a proof to make the Contractor liable to pay the

penalty.

1.2.4.3 Protection of the Environment

The Contractor has to allow for complying with his obligations for safety, security

and protection of the environment described in the Contract Documents included in

the related Sub-Clauses of the Conditions of Contract. The Contractor is not allowed

to dispose or dump any kind of waste materials into the river. The contractor has to,

at the end of the project, remove and clean the waterway of all the temporary

constructions that it has built for the purpose of securing temporary supports or

restraints for the permanent structures, installations for safety measures etc. and

which do not ultimately form the part of the permanent structure.

1.2.4.4 As-Built Drawings

The Contractor shall furnish sets of as-built Drawings of the Works to the Engineer,

showing the permanent works as actually constructed, within one month of

completion of the Works. Included in the sets of as-built Drawings will be revisions

of Tender Drawings and Drawings supplied to the Contractor during the Contract as

well as revisions of drawings supplied by the Contractor during the Contract. The

As-built drawings submitted by the Contractor will be subject to the approval of the

Engineer.


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1.2.5 Maintenance and demobilization

The Contractor shall properly maintain all the infrastructures built at the site such as

office, stores, yards, labor camps etc. till the end of the Project. At the end of the

Project, the Contractor has to remove and demobilize all the temporary

infrastructures that it has built and restore the bridge site to its original condition

and shape. The dismantling and demobilization shall be completed within the

stipulated contract duration.

1.2.6 Measurement and Payment

The site installation shall include cost of all temporary infrastructure facilities, tools,

equipment, test facilities, safety gears, insurance etc. described under Section 1.2. of

this TS. The quantity, size and other specifications of various facilities mentioned

here are the minimum requirements. While the minimum requirements have to be

fulfilled to be eligible for payment under site installation, the contractor may actually

require o provide more that what is specified here for smooth implementation of the

project. If the Engineer finds the site facilities provided by the contractor as per the

minimum requirement in this TS inadequate for smooth or proper implementation

of the works, he will have the right to demand the contractor to install/provide

addition facilities/installations for which contractor cannot claim additional

payment.

By signing the contract, the Contractor confirms that all efforts and costs to fulfill the

task under the site installation are included in his rates. He agrees not to ask for

additional payment.

After full completion of the site installation works as specified, the contractor shall

be eligible for 85% of the total lump sum quoted price under this item. The remaining

15% shall be released only after the contractor decommissions and demobilizes all

the temporary infrastructures that it had built and restore the bridge site to its

original condition and shape.

1.2.7 Pay items shall be:

1) Site Installation (facilities, tools, plant, equipment,

insurance and so forth) Lump Sum


Page | 24 of 112

SECTION 2

2.0 EARTH WORK


Page | 25 of 112

2.1 CLEARING AND GRUBBING

2.1.1 General

While executing the clearing and grubbing works, the trees, shrubs, pole lines,

fences, monuments, pipe lines etc. within or adjacent to the work site which are not

to be disturbed shall be protected properly from damage by the contractor at his

own cost and nothing extra shall be paid for this.

The contractor shall take adequate precautions against soil erosion, water pollution,

etc. wherever required. Before start of work/operations, the contractor shall submit

to the Engineer his work plan for approval including the procedures to be followed

for disposal of waste materials, etc. and the schedules for carrying out temporary or

permanent erosion control works as stipulated under the earth work.

Trunks, branches and stumps of trees shall be cleaned of limps & roots and stacked.

Also boulders, stones and other usable materials shall be neatly stacked at spots as

directed by the Engineer.

All branches of trees extending to the work site or above roadway shall be trimmed

as directed by the Engineer and such work shall be considered incidental to the

clearing and grubbing for which no separate payment shall be made.

Methods, tools and equipment to be adopted for the work shall be such which will

not affect the property to be preserved. Only such methods, tools and equipment as

approved by the Engineer shall be adopted in the work. If so desired by the

Engineer, the Contractor shall demonstrate the efficacy of the type of equipment to

be used before the commencement of the work.

2.1.2 Clearing jungle

The work shall consist of cutting, removing and disposing of all materials such as

rank vegetation, grass, brush-wood, shrubs, stumps trees and saplings of girth up to

300 mm measured at a height of 1m above ground level which in the opinion of

Engineer are unsuitable for incorporation in the works. Where clearance of grass is

only involved, no payment shall be made under the item.


Page | 26 of 112

The roots of trees shall be dug at least up to 600mm from ground level or 150mm

below sub grade level whichever is lower. All holes or hollows formed by digging

up roots shall be carefully filled up with earth, well rammed and levelled.

2.1.2.1 Measurements

Only the area over which the jungle cutting has been done shall be measured. The

length and breadth shall be measured and area calculated in square metre correct to

two places of decimal.

Cutting and removing of roots of trees of girth above 300 mm at a height of 1m

above ground level shall be made separately in terms of number according to the

sizes.

2.1.2.2 Rates

The rate shall cover the cost of carrying out all the required operations including cost

of labour, materials, equipment hired, tools and plants, and incidentals necessary to

complete the work. The rate also includes removal of stumps of trees less than

300mm in girth excavation, back filling to required density, where necessary, and

handling, salvaging, piling and disposing of the cleared materials with all lift and

lead up to 50m.

2.1.3 Felling of Trees

While clearing jungle growth, trees 300mm and above in girth (measured at a height

of one metre above ground level) to be cut, shall be approved by the Engineer and

then marked at site. Felling trees shall include taking out roots up to 600mm below

ground level or 150mm below sub-grade level whichever is lower.

All excavation below general ground level arising out of the removal of trees,

stumps etc. shall be filled with suitable material in 200mm layer and compacted

thoroughly so that the surfaces at these points conform to the surrounding area. The

trunks and branches of trees shall be cleared of limbs and tops and cut to suitable

pieces as directed by the Engineer. Wood, branches, twigs of trees and other useful

material shall be the property of the Employer. The serviceable materials shall be

stacked in the manner as directed by the Engineer.

All unserviceable materials shall be disposed off as per the directions of the

Engineer.


Page | 27 of 112

2.1.3.1 Measurements

Felling of trees (girth measured at a height of one metre above ground level or top of

the stump if the height of the stump is less than 1m from the ground) shall be paid

for in terms of number according to sizes given above.

2.1.3.2 Rate

The rate shall cover the cost of carrying out all the required operations including cost

of labour, materials, equipment hired/owned, tools and plants, and incidentals

necessary to complete the work. The rate also includes removal of stumps of trees

greater than 300mm in girth excavation, back filling to required density, where

necessary, and handling, salvaging, piling and disposing of the cleared materials

with all lift and lead up to 50m.

Where a contract does not include separate items of clearing or grubbing the same

shall be considered incidental and the contract unit prices for the same shall be

considered as including clearing and grubbing operations.

2.1.4 Pay Items

1) Clearing jungle including uprooting of rank vegetation,

grass, brushwood, saplings and trees of girth up to 300mm m2

measured at height of 1m above ground level and disposal

of rubbish within 50m lead.

2) Felling trees of Girth 300 mm and more (girth measured

at a height of 1m above ground level) including cutting of no.

trunks and branches, removal of roots and stacking of

serviceable materials and disposal of rubbish within 50m lead.

2.2 EXCAVATION AND BACKFILL FOR STRUCTURES

2.2.1 General

This work shall consist of excavation, removal and satisfactory disposal of all

materials necessary for the construction in accordance with requirements of these


Page | 28 of 112

specifications and the lines, grades and cross-sections shown in the drawings or as

indicated by the Engineer.

It shall also include backfilling of the excavated foundations not occupied by the

structures and compacted filling with suitable materials of the abutments, return

walls, wing walls and retaining walls.

The excavation shall be deemed to be carried out by machine. For excavation by

machines, materials shall be classified as: -

All kinds of soil

Generally, any strata, such as sand, gravel, loam, clay, mud, black cotton soil,

moorum, shingle, river bed boulders, soiling of roads, paths etc. and hard core

macadam surface of any description (water bound, grouted tarmac etc.), lime

concrete, mud concrete and their mixtures. This category includes both ordinary and

hard soil.

SPECIFICATIONS FOR BUILDING & ROAD WORKS 2009

All kinds of rocks

This includes all categories of rocks - ordinary rock, hard rock requiring/not

requiring blasting, hard rock requiring chiselling. This category doesn’t include hard

rock excavation/cutting in the areas where conventional blasting is prohibited and

requires silent blasting operation. The rock cutting by silent blasting if required shall

be measured and paid for separately.

2.2.1.1 Setting out

After the site has been cleared, the limits of excavation shall be set out true to lines,

curves, slopes, grades and sections as shown on the drawings or as directed by the

Engineer. The Contractor shall provide all labour, survey instruments and materials

such as strings, pegs, nails, bamboos, stones, lime, mortar, concrete, etc., required in

connection with the setting out of works and the establishments of bench marks. The

Contractor shall be responsible for the maintenance of the benchmarks and other

marks and stakes as long as, in the opinion of the Engineer, they are required for the

work.

The ground levels shall be taken at 5m to 15m intervals in uniformly sloping ground

and at closer intervals where local mounds, pits or undulations are met with. The


Page | 29 of 112

ground levels shall be recorded in field books and plotted on plans. Plans shall be

drawn to a suitable scale and North direction and position of benchmark shall be

shown on the plans. The contractor and the Engineer shall sign the plan before the

earthwork is started. The contractor at his own cost shall supply the labour required

for taking levels.

2.2.1.2 Stripping and storing topsoil

When so directed by the Engineer, the topsoil existing over the sites of excavation

shall be stripped to specify depths and stockpiled at designated locations for re-use

in covering embankment slopes, cut slopes, and other disturbed areas where re-

vegetation is desired. Prior to stripping the topsoil, all trees, shrubs etc. shall be

removed along with their roots, with the approval of the Engineer.

2.2.2 Excavation

All excavations shall be carried out in conformity with the directions laid herein-

under and in a manner approved by the Engineer. The works shall be so done that

the suitable materials available from excavation are satisfactorily utilized as decided

upon beforehand.

While planning of excavations, the Contractor shall take all adequate precautions

against soil erosion, water pollution etc. and take appropriate drainage measures to

keep the sites free of water.

The excavations shall conform to the lines, grades, side slopes and levels shown on

the drawings or as directed by the Engineer. The Contractor shall not excavate

outside the limits of excavation. Subject to the permitted tolerances, any excess

depth/ width excavated beyond the specified levels/dimensions on the drawings

shall be made good at the cost of the Contractor with the suitable material of

characteristics similar to that removed and compacted.

All debris and loose materials on the slopes of cutting shall be removed. No

backfilling shall be allowed to obtain required slopes excepting that when boulders

or soft materials are encountered in the cut slopes, these shall be excavated to

approved depth on instructions of the Engineer and the resulting cavities filled with

suitable materials and thoroughly compacted in an approved manner.

4


Page | 30 of 112

After excavation, the sides of the excavated areas shall be trimmed and the area

contoured to minimize erosion and ponding, allow for natural drainage to take

place. If trees were removed, new trees shall be planted, as directed by the Engineer.

The cost of planting new trees shall be deemed to be incidental to the work.

The elevations of the bottoms of footings shown on the Drawings are approximate

only and the Engineer may order in writing such changes in the dimensions or

elevations of footings as may be deemed necessary to secure a satisfactory

foundation.

Boulders, logs and other objectionable material encountered in excavation shall be

removed. After each excavation is complete the Contractor shall notify the Engineer

to that effect and no footings, bedding material or structure shall be placed until the

Engineer has approved the depth of excavation and the character of the foundation

material.

The foundation material shall be cleared of all loose material and cut to a firm

surface, either level or stepped or serrated, as specified or shown on the Drawings or

directed by the Engineer.

2.2.2.1 Methods, tools and equipment

Only such methods, tools and equipment as approved by the Engineer shall be

adopted/used in the work. If so desired by the Engineer, the Contractor shall

demonstrate the efficacy of the type of equipment to be used before the

commencement of the work. Methods, tools and equipment to be adopted for the

work shall be such which will not affect the property to be preserved

2.2.2.2 Rocks excavation:

Excavation in ordinary rock shall be carried out by crowbars, pickaxes or pneumatic

drills.

Blasting operations are generally not required in this case. If the contractor wishes to

resort to blasting, he can do so with the permission of Engineer, but nothing extra

will be paid to him on this account.

Excavation in hard rock shall be done by chiseling where blasting operation is

prohibited or is not applicable. In trenches or drains where blasting is not otherwise

prohibited, the excavation in hard rock shall be carried out by blasting in the first


Page | 31 of 112

instance and finally by chiseling so as to obtain the correct section of the trench as

per drawing. The blasting operation shall be strictly as per latest RGOB blasting

manuals.

2.2.2.3 Blasting

The contractor shall obtain a licence from the competent authority for obtaining and

storing the explosives. The contractor shall procure the explosives, fuses, detonators

etc. from the Government or as per the provision in terms and condition of the

contract. The Engineer or his representative shall have the right to check the

contractor's store and accounts of explosives. The contractor shall provide facilities

for this.

All blasting work shall only be done under careful supervision of trained personnel

and the contractor shall take all precautions as per rules for blasting operations.

The contractor shall be responsible for any damage arising out of accident to the

workmen, public or property due to storage, transportation and use of explosive

during blasting operations.

2.2.2.4 Disposal of Excavated Material

Excavated material classified as suitable by the Engineer shall generally be utilized

as backfill or embankment fill. Surplus suitable material shall be stockpiled at the

Site. Excavated suitable material for use as backfill shall be deposited by the

Contractor in spoil heaps at points convenient for re-handling of the material during

the backfilling operation and approved by the Engineer.

Excavated material classified as unsuitable as backfill by the Engineer shall be

carried to waste.

Excavated material shall be deposited in such places and in such a manner as not to

cause damage to roads, services or property either within or outside the right-of-way

and so as to cause no impediment to the drainage of the site or surrounding area.

The location of spoil heaps shall be subject to the approval of the Engineer who may

require that the reference lines and the traverse lines of any part of the structure be

kept free of obstruction.


Page | 32 of 112

2.2.2.5 Cofferdams

The term “cofferdam” denotes any temporary or removable structure, constructed to

hold the surrounding earth, water or both, out of the excavation, whether such

structure is constructed of earth, timber, steel, concrete or any combination of these.

The term includes earth dikes, timber cribs, sheet piling, removable steel shells and

all bracing; and it shall be understood to include excavation enclosed by pumping

wells and well points.

The cost of cofferdams, if required to be provided, is always to be included in the

tender rates/prices for the permanent work and shall not be paid extra.

The Contractor shall submit upon request, drawings showing his proposed method

of cofferdam construction. Approval of the drawings by the Engineer will not in any

way relieve the Contractor of the responsibility for the adequacy of the design for

strength and stability.

Unless specified otherwise, the cofferdams shall be removed after the completion of

the sub-structure. The removal shall be effected in such a manner as not to disturb or

mar the finished work. The Engineer may order the Contractor to leave any part or

the whole of the cofferdam in place.

When conditions which, in the opinion of the Engineer, render it impossible to de-

water the foundation before placing the footing are encountered, the Engineer may

require the construction of a concrete foundation or seal of such dimensions as he

may consider necessary, and of such thickness as to resist any possible uplift. The

concrete for such seal shall be placed as shown on the Drawings or required by the

Engineer. The foundation shall then be de-watered and the footing placed. When

weighted cribs are used and the weight is used to overcome partially the hydrostatic

pressure acting against the bottom of the foundation seal, special anchorages such as

dowels or keys shall be provided to transfer the entire weight of the crib to the

foundation seal. When a foundation seal is placed under water the cofferdam shall

be vented at low water as directed.

Cofferdams shall be constructed so as to protect newly cast concrete from sudden

rising of the water and to prevent damage to the foundation by erosion.

2.2.2.6 Pumping and Bailing

Pumping and bailing from the interior of any foundation enclosure shall be done in

such a manner as to preclude the possibility of the movement of water through or


Page | 33 of 112

alongside any concrete being placed. No pumping or bailing will be permitted

during the placing of concrete and for a period of at least 24 hours thereafter unless

it is done from a suitable pump separated from the concrete work by a watertight

wall or from well points.

Excavations shall be as dry as possible prior to and during placing concrete. Placing

concrete under water will only be permitted if indicated on the Drawings or

approved by the Engineer.

2.2.3 Filling

2.2.3.1 Foundation Fill Material

Material for foundation fill shall be a natural or artificial mixture of sand or other

mineral aggregate, free from vegetable matter, soft particles and excess clay and

shall consist of suitably graded sand to one of the grading envelopes A to C of Table

2.2-1, gravel or stone as shown on the Drawings or as required by the Engineer, or

concrete. Concrete for foundation fill shall conform to the general requirements of

Section 3.1. Concrete to be placed under water shall conform to the requirements of

Section 3.1.4.13. Concrete used as foundation fill in dry excavation shall be M15.

Table 2.2-1 Grading of foundation fill material

A B C D E

Nominal

fineness

modulus

Not less

than 2.8

1.5-2.8 1.0-1.5 0.8-1.0 0.5-0.8

Sieve size

(mm)

% passing by weight 10 100 100 100 100 100

5.0 90-95 95-100 100 100 100

2.4 70-90 90-100 100 100 100

1.2 45-70 70-95 95-100 100 100

0.6 25-45 40-80 85-100 95-100 100

0.3 10-20 10-50 50-80 70-90 80-95

0.15 0-2 0-20 5-25 15-40 30-60


Page | 34 of 112

Grading outside the above limits may in certain circumstances be approved by the

Engineer. Such permission shall be in writing.

2.2.3.2 Backfill Material

The excavated materials shall be used for backfilling if found suitable and approved

by the Engineer. The source (borrow pit) and type of fill material have to be

approved by the Engineer.

The earth shall be free from all roots, grass and rubbish. All lumps and clods

exceeding 80mm in any direction shall be broken and each layer shall be

consolidated by ramming and rolling, etc. Watering shall be done, if so stipulated.

The top surface of the finally finished area shall be neatly dressed.

The finished formation levels, in case of filling shall be kept higher than the required

levels, by making an allowance of 10% of depth of filling for future settlement in case

of ordinary consolidated fills, and 5% in case where consolidation is done by heavy

mechanical machinery under optimum moisture conditions.

The fill materials around pier foundations shall be carried out using boulders in

order to prevent the slope against scouring by river. The work shall be carried out as

per the drawings and instruction of the Engineer. The boulder/stone filling shall be

carried out in layers of at least 500 mm thickness and one boulder/stone shall not be

lighter than 200 kg. The boulders shall be so placed that they interlock against each

other to stay in position securely against the river current. The interlock boulders/

stone may be of smaller sizes but its composition should not be more than 20% of

overall fill materials.

The backfill materials for the filter layer behind the abutment & return walls shall be

coarse gravel as per drawing. The filter materials to be used have to be approved by

the Engineer. Handling, loading, offloading, transportation and all necessary work

shall be included in the rate.

2.2.3.3 Backfilling

All spaces excavated under these Specifications and not occupied by the permanent

structure shall be backfilled. However, the finished level of the back fill shall be as

per the lines and levels of the finished profile of the slope shown in the design

drawings. Backfilled material shall fully comply with this Specification and adequate


Page | 35 of 112

provision shall be made for drainage. No backfilling shall commence until

permission has been given by the Engineer.

Backfilling shall be well compacted and shall be done in layers, not exceeding

200mm in each layer. Each layer shall be watered, rammed and consolidated before

the succeeding one is laid.

Special care shall be taken to prevent any unduly high pressure against the

structures. In placing backfill and embankment, the material shall be placed insofar

as possible to approximately the same height on both sides of the structure at the

same time. If conditions require backfilling appreciably higher on one side, the

additional material on the higher side shall not be placed until permission is given

by the Engineer that the structure has enough strength to withstand any pressure

created.

2.2.4 Plate Load Test on Foundations

After the foundation excavation is complete and prior to casting of footing slabs, the

Contractor shall carry out plate load tests on at least two foundations – one test on

pier foundation and another one on abutment. The tests shall be carried out to

determine bearing capacity of soil and its settlement in accordance with IS: 1888

Method of Load Test on Soils.

The Contractor shall be responsible for arranging equipment, tools and other

materials necessary for carrying out test at site and determining bearing capacity of

soil foundation at his own costs. The cost of carrying the plate load test is to be

included in the tender rates/prices and shall not be paid extra.

The safe bearing capacity of foundations thus calculated from the plate load tests

shall be at least 400 kN/m3. If the safe bearing capacity of foundations are less than

400 kN/m3, additional excavations shall be carried out for depth of 1.5 m and the

soil underneath replaced with plain cement concrete (PCC) of class M 15. The cost of

carrying out additional excavations and providing replacement concrete, if necessary

shall be paid as additional items.

If the plate load test results are unsatisfactory and inconclusive, the Contractor shall

carry out additional plate load tests at his own cost as directed by the Engineer.


Page | 36 of 112

2.2.5 Measurements

The volume of excavation shall be measured in cubic Meters of excavated

undisturbed material.

The quantity of excavation for structures to be measured for payment shall include

excavation for all structures. The measured volume shall be the excavation plan

outline, bounded on the bottom by the plane of the underside of the blinding

concrete under the reinforced concrete footing and on the top by the surface of the

existing ground and on the sides by vertical planes of the footings and the volume

so measured shall be term as “Solid Volume”.

Additional excavations for slope cutting, working space and for other purposes of

construction ease and convenience shall not be paid extra. The cost for such

additional excavation works is deemed to be included in the unit rates under the

payable items and quantities of the excavation works. The removal of slides, cave-

ins, silting or filling shall also neither be measured nor paid for.

The soil/rock excavation for construction/widening of approach roads to the

bridge however shall be measured as actual volume of excavation as per the

drawings or as directed by the Engineer as per the actual requirement of the site.

The contractor has to do a detail survey of the area to be excavated as per direction

of the Engineer prior to and after the excavation to arrive at the actual volume of

excavation. The measured volume shall be in-situ volume and no allowance shall be

allowed for bulking and other forms of volume change.

The measured volume for backfilling and filling behind the abutment/return

walls and boulder filling around piers shall be the backfilling plan outline bounded

at the bottom by the plane of the underside of the blinding concrete under the

reinforced concrete footing and on the top by the surface of the finished ground and

on the sides by vertical planes of the footings minus the volume occupied by the

permanent structure. However, the areas around the foundations excavated by the

contractor for creating working space, stabilizing excavation slope, etc. shall be

backfilled to required degree of compaction and using the same backfill materials/

boulder filling as per this specification at contractor’s own cost.

The length, breadth and depth/height shall be measured correct to 10 mm. In case

the measurements are taken with staff and level, the level shall be recorded correct

to 5mm and depth of cutting and heights of filling calculated correct to 5mm. The


Page | 37 of 112

cubical contents shall be worked out to the nearest two places of decimal in cubic

metres.

2.2.6 Payment

The rates shall cover the cost for carrying out all the required operations including

cost of labour, materials, equipment hired/owned, tools and plants, plate load test

and incidentals necessary to complete the work. In case of rock, the rate shall also

include the cost of all operations of blasting with explosive and accessories as

mentioned above.

2.2.7 Pay Items

1) Excavation for foundations of Abutments A1 and A2 true to the

lines and levels shown in the relevant drawings. The excavation

shall be measured and paid for as Solid Volume:

a) All kinds of foundation soil/ rock m3

2) Excavation for pier foundations P1, P2 & P3 true to the

lines and levels shown in the relevant drawings. The excavation

shall be measured and paid for as Solid Volume:

a) All kinds of foundation soil/ rock m3

3) Backfilling behind abutments and return walls to required degree

of compaction. m3

4) Backfilling with boulders around pier foundations. The quantity

covers boulder/stone filling around all three pier foundations

of the bridge (P1, P2 & P3). m3

5) Providing and laying of coarse gravel (filter layer) behind abutments

and return walls as per BoQ and the drawings. m3


Page | 38 of 112

SECTION 3

3.0 STRUCTURES


Page | 39 of 112

3.1 CONCRETE FOR STRUCTURES

3.1.1 Standards

The concrete materials, production, methods, testing & admixtures shall conform to

the latest revisions of the following Indian Standards or, where not covered by these

standards, to the equivalent International Standards:

IS: 8112 43 grade Ordinary Portland Cement.

IS: 12269 53 grade Ordinary Portland Cement.

IS: 383 Coarse & fine aggregates from natural sources for aggregates.

IS: 456 Code of practice for plain & reinforced concrete.

IS: 457 Code of practice for general construction of plain & reinforced concrete for

dams & other massive structures.

IS: 516 Method of test for strength of concrete.

IS: 1199 Methods of sampling & analysis of concrete.

IS: 1489 Portland Pozzolana cement.

IS: 2386 Methods of test for aggregates for concrete.

IS: 2505 Concrete vibrators – immersion type – general.

IS: 2506 General requirements for screed board concrete vibrators.

IS: 4082 Stacking & storage of construction materials & components at site–

recommendations.

IS: 7861 Code of practice for extreme weather concreting.

IS: 9103 Admixtures for concrete.

IS: 10262 Recommended guidelines for concrete mix design.

IRC: 112 Code o Practice for Concrete Road Bridges

In cases of conflict between or among the above standards & the specifications given

herein, the decision of the Client shall prevail.

3.1.2 Description

This work shall consist of the construction of all or portions of concrete structures, of

the required grades and types, with or without reinforcement and with or without

admixture, in accordance with these Specifications and to the lines, levels, grades

and dimensions shown on the Drawings and as required by the Engineer.

The cement concrete shall consist of a mixture of cement, water and coarse and fine

aggregate with or without admixture.


Page | 40 of 112

3.1.3 Materials

3.1.3.1 Specifications for Materials

A) Cement

Cement shall conform to the requirements of Indian Standard as mentioned in

Article 3.1.1 of this specification unless other types are indicated on the Drawings or

specified by the Engineer.

One of the types of the cements, specified below shall be used.

a) Ordinary Portland cement conforming to IS: 269

b) Portland blast furnace slag cement conforming to IS: 455

e) Portland pozzolana cement conforming to IS: 1489

Bagged or bulk cement which has partially set or which contains lumps of caked

cement shall be rejected. The use of cement reclaimed from discarded or used bags

shall not be permitted.

B) Water

Water used for mixing mortars and concrete shall be clean and reasonably free from

injurious quantities of deleterious materials such as oils, acids, alkalis, salts and

vegetable growth. Generally potable water shall be used. Where water can be shown

to contain any sugar or an excess of acid, alkali or salt, the Engineer may refuse to

permit its use. As a guide, the following concentrations may be taken to represent

the maximum permissible limits of deleterious materials in water.

(a) Limits of acidity: - To neutralize 200 ml sample of water, it should not require

more than 2 ml of 0.1 N caustic soda solutions.

(b) Limits of Alkalinity: - To neutralize 200 ml sample of water it should not require

more than 0.1 ml of 0.1 N hydrochloric acid.

(c) Percentage of solids should not exceed: -

Organic 200 ppm (0.02%)

Inorganic 3000 ppm (0.30%)

Sulphates 500 ppm (0.05%)

Alkali chlorides 1000 ppm (0.1%)


Page | 41 of 112

Water found satisfactory for mixing is suitable for curing concrete. However, the

water used for curing should not produce any objectionable stain or deposit on the

concrete surface.

The use of river water will be subject to the approval of the Engineer. Such approvals

may be withdrawn from time to time depending on the condition of the river.

C) Admixtures

Admixtures or any other additions shall not be used except with the written

approval of the Engineer.

Admixtures, if specified or permitted, shall fully conform to the requirements of

Indian Standard IS: 9103

D) Coarse Aggregate

Coarse aggregate for all types of concrete with the exception of blinding concrete

shall consist of hard durable crushed or broken rock and generally conform to the

requirements of Indian Standard IS: 383 (or AASHTO Standard Specification M 80 or

ASTM C33 / C33M – 08). Coarse aggregate shall be clean, free from dust and other

deleterious material.

The amounts of deleterious substances shall not exceed the following limits:

1) Soft fragments; 2% by mass

2) Clay lumps; 0.25% by mass

3) Material Passing the 0.075 mm sieve; 0.50% by mass if clay, 1.50% by mass if

fractures dust

In addition, coarse aggregates shall comply with the following:

1) Thin or elongated pieces; Flakiness Index less than 30

2) The aggregate crushing value shall be less than 30% and the ten percent fines

value shall be greater than 150 kN.


Page | 42 of 112

The grading of coarse aggregate of shall conform to Table 3.1-1below.

Table 3.1-1 Grading Requirements Coarse Aggregate

In heavily reinforced structures with difficult casting conditions smaller size

aggregates may be used if approved by the Engineer.

E) Fine Aggregate

Fine aggregate shall consist of natural sand and fine aggregates from different

sources of supply shall not be mixed or stored in the same pile.

The amounts of deleterious substance when tested shall not exceed the following

limits:

1) Friable Particles; 0.5% by mass

2) Coal and Lignite; 0.5% by mass

3) Material passing the 0.075 mm sieve; 3.0% by mass

4) Any other deleterious materials shall not cause a strength reduction of the

concrete of more than 5% in relation to the strength of concrete free of the concerned

deleterious material.


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The grading shall normally be in accordance with Table 3.1-2. In the event that it is

not possible to obtain regular supplies of sand conforming to this grading, the

Engineer may approve the adoption of an alternate grading conforming to the

requirements of the mix design. However, any additional cost results from changes

in aggregate proportions or additional cement contents required to achieve the

specified strengths, when using these alternative grading, shall be borne by the

Contractor and shall not be reimbursed.

Table 3.1-2 Grading Requirements for Fine Aggregate

Grading Requirements for Fine Aggregate

Sieve Size (mm) % Passing by Weight

10.0 100 5.0 95-100 1.2 45-80 0.30 10-30 0.15 2-10

3.1.3.2 Testing of Materials

A) Cement

Cement shall be in accordance with Indian Standard. The Contractor must provide

the Engineer with manufacturer’s certificates indicating compliance.

Cement shall be sampled and tested for fineness, setting time and strength in

accordance with IS: 615 at the Contractor’s expense. The Contractor shall notify the

Engineer of delivery dates so that there will be sufficient time for sampling the

cement, either at the mill or upon delivery. If this is not done, the Contractor may be

required to re-handle the cement in the store for the purpose of obtaining the

required samples.

Sampling shall normally be instructed by the Engineer for every batch of cement

prior to this cement being incorporated in the Works.

B) Water


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The water proposed by the Contractor to be used in mixing or curing concrete shall

be tested by methods described in Indian Standard or AASHTO Test Method T 26

[or ASTM C1602 / C1602M – 06].

In sampling water for testing, care shall be taken that the containers are clean and

that samples are representative.

When comparative tests are made with a water of known satisfactory quality, any

indication of unsoundness, marked change in time of setting, or a reduction of more

than 10 percent in mortar strength, shall be sufficient cause for rejection of the water

under test.

The water shall be tested at a recognized laboratory approved by the Engineer. The

test result shall be signed by the laboratory. The water shall be tested before

commencement of work or if the source is changed or at any time required by the

Engineer. All testing shall be carried out at the Contractor’s expense.

C) Admixtures

Chemical admixtures are not to be used until permitted by the Engineer. In case their

use is permitted, the type, amount and method of use of any admixtures proposed

by the Contractor shall be submitted to the Engineer for approval. The minimum

cement specified shall not be reduced on account of the use of the admixtures.

The contractor shall provide the following information concerning each admixture to

the Engineer:

a. Normal chemical dosage and detrimental effects if any of under dosage and

over dosage.

b. The chemical names of the main ingredients in the admixtures.

c. The chloride content, if any, expressed as a percentage by weight of

admixture.

d. Whether or not the admixture leads to the entrainment of air when used in

the manufacturer’s recommended dosage.

e. Where two or more admixtures are proposed to be used in any one mix, the

manufacturer’s written confirmation of their compatibility.

3. In reinforced concrete, the chloride content of any admixture used shall not

exceed 2 percent by weight of the admixtures as determined in accordance

with IS: 6925 and the total chloride and sulphate contents in concrete mix shall

not exceed 1.15 and 4.0 percent respectively by weight of cement.


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The admixtures when used shall conform to IS: 9103. The suitability of all

admixtures shall be verified by trial mixes.

The addition of calcium chloride to concrete containing embedded metal will not be

permitted under any circumstances.

Retarding admixtures when used shall be based on ligno-sulphonates with due

consideration to clause 5.2 and 5.3 of IS: 7861

D) Aggregates

1) Selection and Approval

From the aggregate materials proposed by the Contractor, samples shall be selected

according to Standard Testing Procedure and in the presence of the Engineer. The

samples shall be tested at the site laboratory or at an approved testing laboratory for

conformance with Section 3.1.3.1 of these Specifications.

2) Quality Control

The quality control of the aggregate shall be as directed by Engineer. Grading shall

normally be checked daily.

Moisture contents of fine aggregate shall be determined daily and at any time when

a change in moisture content is expected.

If the Contractor proposes to change the source of aggregate, the Engineer shall be

informed in advance and in no case less than 3 weeks before the new aggregate shall

be used.

3.1.3.3 Composition of Concrete

A) Classes of Concrete

Concrete with cement type as specified for incorporation in the Works shall be of the

classes indicated on the Drawings and shall comply with Table 3.1-3.

Table 3.1-3 Concrete classes


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Concrete Class

28 days Characteristic Strength (N/mm2) (15cmx15cm15cm

Cube)

Maximum Size of Coarse

Aggregate (mm)

Minimum Cement

Content (Kg/m3)

M7 7

40

20

180

210

M10 10

40

20

210

240

M15 15

40

20

250

280

M20 20

40

20

300

320

M25 25

40

20

340

360

M30 30

40

20

370

400

M35 35

40

20

400

430

B) Proportioning

When designing the concrete mix, the Contractor shall consider the following

conditions:

1) Strength

The class of the concrete is to be as shown on the Drawings. The class is the specified

characteristic cube strength at 28 days. Concrete mixes shall be designed to comply

with Specifications Section 3.1.3.4.

2) Water/Cement Ratio


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The ratio of free water to cement when using saturated surface dry aggregate shall

be as low as possible and not exceed 0.50 by weight for all concrete, except for

blinding concrete where it shall not exceed 0.6, unless approved by the Engineer.

For concrete in barriers, edge beams and bridge decks directly exposed to traffic or

concrete in pile caps or abutments in contact with the ground, the water cement ratio

shall not exceed 0.45, unless approved by the Engineer.

3) Minimum Cement Content

As indicated for the respective class in Table 3.1-3

4) Minimum Filler Content

Filler content (fine aggregate less than 0.25 mm and cement) shall not be less than as

follows (except for mass concrete).

Maximum coarse aggregate size (mm) 20 40

Minimum filler content (kg/m3 of concrete) 435 350

5) Coarse Aggregate

The maximum size of coarse aggregate will generally be stated on the Drawings;

either 40 mm or 20 mm, in accordance with Table 3.1-1. Grading and quality is to

comply with the requirements of Section 3.1.3.1.

6) Fine Aggregate

The grading and quality is to comply with the requirements of Section 3.1.3.1.

7) Workability

The concrete shall be of suitable workability to obtain full compaction. Slumps

measured in accordance with approved standard procedure shall not exceed 75 mm

unless otherwise indicated on the Drawings or approved by the Engineer.

C) Trial Mixes

After the Contractor has received approval for the cement and aggregate to be used,

he shall prepare trial mixes with concrete of designed proportions to prove and

establish workability, strength, water cement/ratio, surface criteria etc. Methods of


Page | 48 of 112

transporting fresh concrete and the compaction equipment shall be considered. The

trial mixes shall be made and compacted in the presence of the Engineer, using the

same type of plant and equipment as will be used for the Works.

From each trial mix, cylinders or cubes shall be made and tested in accordance with

Section 3.1.3.4.

From the same mix as that from which the test specimens are made, the workability

of the concrete shall be determined by the slump test. The remainder of the mix shall

be cast in a wooden mould and compacted. After 24 hours the sides of the mould

shall be struck and the surface examined in order to satisfy the Engineer that an

acceptable surface can be obtained with the mix.

The trial mix proportions should be approved if the required strength is obtained

from tests carried out in accordance with Section 3.1.3.4 and the consistency and

surface is to the satisfaction of the Engineer.

When a mix has been approved, no variations shall be made in the mix proportions,

or in the type, size, grading zone or source, of any of the constituents without the

consent of the Engineer, who may require further trial mixes to be made before any

such variations are approved.

Until the results of trial mixes for a particular class have been approved by the

Engineer, no concrete of the relevant class shall be placed in the Works.

When the Contractor intends to purchase factory-made precast concrete units, trial

mixes may be dispensed with provided that evidence is given to satisfy the Engineer

that the factory regularly produces concrete which complies with the Specifications.

The evidence shall include details of mix proportions, water/cement ratios, slump

tests and strengths obtained at 28 days.

3.1.3.4 Control of Concrete Quality

A) General

The Contractor shall assume the full responsibility for the quality of the concrete

conforming to these Specifications and this responsibility shall not be relieved by the

testing carried out and approved by the Engineer.


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The Contractor shall thus at his own discretion establish additional testing

procedures as necessary.

B) Control of Concrete Production

1) Materials

Materials used shall be tested in accordance with the relevant sections of this

specification.

2) Plant and Equipment

Batching plants will be tested by the Contractor in a manner approved by the

Engineer before any major concrete casting and at any other time if requested by the

Engineer. The concreting plant and equipment shall have a capacity for atleast 80m3

of concreting per day.

3) Fresh Concrete

The frequency of slump tests shall be as directed by the Engineer, with at least one

test per 25 m3 of concrete.

C) Control of Strength

C.1) Sampling and Testing

The Contractor shall take samples of the concrete for testing. The number, frequency

and location shall be decided by the Engineer. A minimum of 3 concrete cubes

should be taken for each day’s casting, or for every 15 m3 of concrete cast in large

pours. The slump of concrete samples shall be measured.

The procedures for sampling and making cubes and testing them shall be as

described in IS: 1199/IS: 516 (or ASTM C873 / C873M - 04e1.)

C.2) Strength Requirement

The results of the testing shall conform to the strength requirements according to IS:

456 or to any mathematically correct statistical test for each casting section.

C.2.1) General


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The characteristic strength of concrete is the 28 days strength below which not more

than 5% of the test results may be expected to fall.

C.2.2) Target Mean Strength

The concrete mix should be designed to have a mean strength greater than the

required characteristic strength by at least the current margin.

The current margin for each particular type of concrete mix shall be determined; it

may be taken as having the smaller of the values given by (1) or (2) below.

C.2.2.1)1.64 times the standard deviation of tests on at least 100 separate batches of

concrete of nominally similar proportions of similar materials and produced over a

period not exceeding 12 months by the same plant under similar supervision.

C.2.2.2)1.64 times the standard deviation of tests on at least 40 separate batches of

concrete of nominally similar proportions of similar materials and produced over a

period exceeding 5 days but not exceeding 6 months by the same plant under similar

supervision.

Where there are insufficient data to satisfy (1) or (2) above, the margin for the initial

mix design should be taken as one-thirds of the characteristic strength for concrete.

This margin should be used as the current margin only until sufficient data are

available to satisfy (1) or (2) above. However, when the required characteristic

strength approaches the maximum possible strength of concrete made with a

particular aggregate, a smaller margin may be permitted by the Engineer for the

initial mix design.

C.2.3) Testing Plan

Each cube shall be made from a single sample taken from randomly selected batches

of concrete.

Compliance with the specified characteristic strength may be assumed if:

1) The average strength determined from any group of four consecutive test

cubes exceeds the specified characteristic strength by not less than 0.5 times the

current margin, and


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2) Each individual test result is greater than 85% of the specified characteristic

strength.

The current margin should be taken to be one-thirds (1/3) of the specified

characteristic strength for concrete, unless as mentioned above a smaller margin has

been established to the satisfaction of the Engineer.

If only one cube result fails to meet the second requirement, then that result may be

considered to represent only the particular batch of concrete from which that cube

was taken provided the average strength of the group satisfies the first requirement.

If more than one cube in a group fails to meet the second requirement or if the

average strength of any group of four consecutive test cubes fail to meet the first

requirement, then all the concrete in all the batches represented by all such cylinders

shall be deemed not to comply with the strength requirements. For the purposes of

this sub-Section, the batches of concrete represented by a group of four consecutive

test cylinder/cubes shall include the batches from which samples were taken to

make the first and the last cubes in the group of four, together with all the

intervening batches.

C.2.4) Action to be taken in the event of Non-Compliance with the Testing Plan

When the average strength of four consecutive test cubes fails to meet the first

requirement in (F), above, the mix proportions of subsequent batches of concrete

should be modified to increase the strength.

The action to be taken in respect of the concrete which is represented by the test-

cubes which fail to meet either of the requirements (or not by correct statistical proof

can be verified to have the required strength) shall be determined by the Engineer.

This may range from qualified acceptance in less severe cases, to rejection and

removal in the most severe cases.

The Engineer may also require the Contractor at his own expenses to prove

statistically the strength, by boring out cores and testing them according to a

program approved by the Engineer. The age of the concrete and degree of hardening

at the time of the new testing shall be considered. The equivalent cylinder/cube

strength shall comply the minimum characteristic strength or as decided by the

Engineer.


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D) Control of Hardening

If the Contractor wants to remove forms and scaffolding earlier than specified

herein, extra test specimens shall be cast by the Contractor in accordance with the

instruction of the Engineer. These specimens shall be tested the day before removal

of the form. On the basis of the test results the Engineer shall take the final decision

on the time for the removal of forms.

3.1.4 Construction Methods

3.1.4.1 General

The Contractor shall in due time and as soon as possible present and discuss his

construction methods and work program with the Engineer and shall obtain his

approval before commencement of any work.

The Contractor shall maintain an adequate number of trained and experienced

supervisors and foremen at the Site to supervise and control the work.

All construction, other than concrete, shall conform to the requirements prescribed

in other Sections of the Specifications, for the particular items of work comprising

the complete structure.

3.1.4.2 Care and Storage of Concrete Materials

A) Storage of Cement

All cement shall be stored in suitable weatherproof buildings or silos which will

protect the cement from dampness. These buildings or silos shall be placed in

locations approved by the Engineer. Provisions for storage shall be ample, and the

shipments of cement as received shall be separately stored in such manner as to

provide easy access for the identification and inspection of each shipment. Storage

buildings shall have a capacity for the storage of a sufficient quantity of cement to

allow sampling at least 14 days before the cement is to be used. Cement shall meet

the test requirements at any time and any cement stored for an elongated time shall

be checked and tested before use regardless of whether it has previously been tested.

B) Storage of Aggregates

Aggregates shall be so stored as to prevent the inclusion of foreign material.

Aggregates shall not be placed upon the finished roadbed. Aggregates of different


Page | 53 of 112

sizes and kinds shall be placed in different stockpiles. Stockpiles of blended coarse

aggregates shall be built up in successive horizontal layers not more than 1 Meter

thick. Each layer shall be completed before the next is started. Should segregation

occur, the aggregates shall be recombined to conform to the grading requirement.

Washed aggregates and aggregates produced or manipulated by methods which

involve the use of water shall be allowed to drain at least 12 hours before use.

3.1.4.3 Preparations before Casting

Before any major casting, the Contractor shall prepare a complete “casting program”

describing staff and labor, consumption of materials, plant, tools and equipment,

reserves of materials, standby plant and equipment, proposed means of handling

and placing the concrete, quality controls etc.

No concrete shall be mixed and placed until the Contractor’s casting program has

been approved in writing by the Engineer.

Equipment and tools necessary for handling materials and performing the work, and

satisfactory to the Engineer as to design, capacity, and mechanical condition, shall be

at the site of the work before casting is started.

If any equipment is not maintained in full working order, or if the equipment as

used by the Contractor proves inadequate to obtain the result prescribed, such

equipment shall be repaired or other suitable equipment substituted or added at the

discretion of the Engineer.

3.1.4.4 Measuring Materials

All material in the mix shall be proportioned by weight or volume, subject to the

approval of the Engineer.

When volume batching is proposed by the Contractor, the exact proportions must be

converted from trial mix weights to volumes, from bulk densities determined in the

laboratory. Written approval from the Engineer is required.

3.1.4.5 Mixing Concrete

A) General


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All concrete shall be mixed in batch mixers, either at the site of construction, at a

central plant, or in transit. Each mixer shall have attached to it in a prominent place,

a manufacturer’s plate showing the capacity of the drum in terms of mixed concrete

and the speed of rotation of the mixing drum.

B) Mixers at Local Site of Construction

Mixers at local sites shall be approved drum-type capable of combining the

aggregate, cement, and water into a thoroughly mixed and uniform mass within the

specified mixing period and of discharging the mixture without segregation. The

mixer shall be equipped with a suitable charging hopper, water storage and a water

measuring device, accurate within 1%. Controls shall be so arranged that the water

can be applied only while the mixer is being charged. Suitable equipment for

discharging the concrete shall be provided. The mixer shall be cleaned at suitable

intervals. The pickup and throw-over blades in the drum shall be replaced when

they have lost 10% of their depth.

The mixer shall be operated at a drum speed of between 15 and 20 revolutions per

minute. The batched materials shall be so charged into the drum that a portion of the

water shall enter in advance of the cement and aggregates and the water shall

continue to flow into the drum for a minimum time of 5 seconds after all the cement

and aggregates are in the drum. Mixing time shall be measured from the time all

materials except water are in the drum and shall, in the case of mixers having a

capacity of 1 cubic Meter or less, not be less than 50 seconds nor more than 70

seconds. In the case of dual drum mixers, the mixing time shall not include transfer

time. The contents of an individual mixer drum shall be removed before a

succeeding batch is emptied therein. Any concrete mixed less than the specified

minimum time shall be discarded and disposed of by the Contractor at his own

expense.

The volume of concrete mixed per batch shall not exceed the mixer’s nominal

capacity in cubic feet or cubic Meters as shown on the manufacturer’s guaranteed

capacity standard rating plate on the mixer; except that an overload up to 20% of the

mixers nominal capacity may be permitted provided concrete test data for strength,

segregation and uniform consistency are satisfactory, and provided no spillage of

concrete takes place.


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Re-tempering concrete by adding water or by other means shall not be permitted.

Concrete which is not of the required consistency at the time of placement shall not

be used and shall be discarded and disposed of by the Contractor at his own

expense.

C) Central Plant Mixers

These mixers shall be of approved drum type capable of combining the aggregate,

cement and water into a thoroughly mixed and uniform mass within the specified

mixing period and of discharging the mixture without segregation. Central plant

mixers shall be equipped with an acceptable timing device that will not permit the

batch to be discharged until the specified mixing time has elapsed. The water system

for a central mixer shall be either a calibrated measuring tank or a meter and shall

not necessarily be an integral part of the mixer.

The mixers shall be cleaned at suitable intervals. They shall be examined daily for

changes in interior condition. The pick up and throw-over blades in the drum shall

be replaced when they have lost 10% of their depth.

In addition to the requirements for mixers at local sites detailed above, central plant

mixers which have a capacity of between 2 and 5 cubic Meters, or greater than 5

cubic Meters, should have a minimum mixing time of 90 and 120 seconds

respectively, provided tests indicate that the concrete produced is equivalent in

strength and uniformity to that attained as stated in the preceding paragraphs.

Mixed concrete shall be transported from the central mixing plant to the site of work

in agitator trucks or, upon written permission of the Engineer, in non-agitator trucks.

Delivery of concrete shall be so regulated that placing is at a continuous rate unless

delayed by the placing operations. The intervals between deliveries of batches shall

not be so great as to allow the concrete in place to harden partially, and in no case

shall such an interval exceed 30 minutes.

D) Agitator Trucks

Unless otherwise permitted in writing by the Engineer, agitator trucks shall have

watertight revolving drums suitably mounted and shall be capable of transporting

and discharging the concrete without segregation. The agitating speed of the drum

shall not be less than two or more than six revolutions per minute. The volume of


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mixed concrete permitted in the drum shall not exceed the manufacturer’s rating nor

exceed 80% the gross volume of the drum.

Upon approval by the Engineer, open-top, revolving-blade truck mixers may be

used in lieu of agitating trucks for transportation of central plant mixed concrete.

Gross volume of agitator bodies expressed in cubic feet or cubic Meters shall be

supplied by the mixer manufacturer. The interval between introduction of water into

the mixer drum and final discharge of the concrete from the agitator shall not exceed

45 minutes. During this interval the mix shall be agitated continuously.

E) Non-Agitator Trucks

Bodies of non-agitating equipment shall be smooth, water-tight metal containers

equipped with gates that will permit control of the discharge of the concrete. Covers

shall be provided when needed for protection against the weather.

The non-agitating equipment shall permit delivery of the concrete to the site of the

work in a thoroughly mixed and uniform mass with a satisfactory degree of

discharge.

Uniformity shall be satisfactory if samples from the one-quarter and three quarter

points of the load do not differ by more than 30 mm in slump. Discharge of concrete

shall be completed within 30 minutes after the introduction of the mixing water to

the cement and aggregate.

F) Truck or Transit Mixers

These shall be equipped with electrically actuated counters by which the number of

revolutions of the drum or blades may readily be verified and the counters shall be

actuated at the commencement of mixing operations at designated mixing speeds.

The mixer when loaded shall not be filled to more than 60% of the drum gross

volume. The mixer shall be capable of combining the ingredients of the concrete into

a thoroughly mixed and uniform mass and of discharging the concrete with a

satisfactory degree of uniformity.

Except when intended for use exclusively as agitators, truck mixers shall be

provided with a water measuring device to measure accurately the quantity of water

for each batch. The delivered amount of water shall be within plus or minus 1% of

the indicated amount.


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Truck mixers may be used for complete mixing at the batch plant and as truck

agitators for delivery of concrete to job sites, or they may be used for complete

mixing of the concrete at the job site. They shall either be a closed watertight

revolving drum or an open top revolving blade or paddle type.

The amount of mixing shall be designated in number of revolutions of the mixer

drum. When a truck mixer is used for complete mixing, each batch of concrete shall

be mixed for between 70 and 100 revolutions of the drum or blades at the rate of

rotation designated by the manufacturer of the equipment as the “mixing speed”.

Such designation shall appear on a metal plate attached to the mixer. If the batch is

at least 0.5 cubic Meters less than guaranteed capacity, the number of revolutions at

mixing speed may be reduced to not less than 50. Mixing in excess of 100 revolutions

shall be at the agitating speed. All materials, including the mixing water, shall be in

the mixer drum before actuating the revolution counter which will indicate the

number of revolutions of the drum or blades.

When wash water (flush water) is used as a portion of the mixing water for the

succeeding batch, it shall be accurately measured and taken into account in

determining the amount of additional mixing water required. When wash water is

carried on the truck mixer, it shall be carried in a compartment separate from the one

used for carrying or measuring the mixing water. The Engineer will specify the

amount of wash or flush water, when permitted, any may specify a “dry” drum if

wash water is used without measurement or without supervision.

When a truck is used for complete mixing at the batch plant, mixing operations shall

begin within 30 minutes after the cement has been added to the aggregate. After

mixing, the truck mixer shall be used as an agitator, when transporting concrete, at

the speed designated by the manufacturer of the equipment as agitating speed.

Concrete discharge shall be completed within 45 minutes after the addition of the

cement to the aggregates. Each batch of concrete delivered at the job site shall be

accompanied by a time slip issued at the batching plant, bearing the time of

departure there from. When the truck mixer is used for the complete mixing of the

concrete at the job site, the mixing operation shall begin within 30 minutes after the

cement has been added to the aggregates.

The rate of discharge of the plastic concrete from the mixer drum shall be controlled

by the speed of rotation of the drum in the discharge direction with the discharge

gate fully open.


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3.1.4.6 Handling and Placing Concrete

The temperature of concrete at the time of placing shall not be below 50C or above

35°C.

In preparation for the placing of concrete all sawdust, chips and other construction

debris and extraneous matter shall be removed from the interior of forms. Struts,

stays and braces, serving temporarily to hold the forms in correct shape and

alignment, pending the placing of concrete at their locations, shall be removed when

the concrete placing has reached an elevation rendering their service unnecessary.

These temporary members shall be entirely removed from the forms and not buried

in the concrete.

Concrete must reach its final position in the forms within 20 minutes of the

completion of mixing, or as directed by the Engineer.

Concrete shall be placed so as to avoid segregation of the materials and the

displacement of the reinforcement. The use of long troughs, chutes and pipes for

conveying concrete from the mixer to the forms shall be permitted only on written

authorization of the Engineer. In case an inferior quality of concrete is produced by

the use of such conveyors, the Engineer may order discontinuance of their use and

the institution of a satisfactory method of placing.

Open troughs and chutes shall be of metal or metal lined. Where long steep slopes

are required, the chutes shall be equipped with baffles or be in short lengths that

reverse the direction of movement.

All chutes, troughs and pipes shall be kept clean and free from coatings of hardened

concrete by thoroughly flushing with water after each run. Water used for flushing

shall be discharged clear of the structure.

When placing operations would involve dropping the concrete more than 1 .5 m, it

shall be deposited through sheet metal or other approved pipes. As far as

practicable, the pipes shall be kept full of concrete during placing and their lower

ends shall be kept buried in the newly placed concrete. After initial set of the

concrete, the forms shall not be jarred and no strain shall be placed on the ends of

reinforcement bars which project.


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Concrete, during and immediately after depositing, shall be thoroughly compacted.

The compaction shall be done by mechanical vibration subject to the following

provisions:

1) The vibration shall be internal unless special authorization of other methods

is given by the Engineer or as provided herein.

2) Vibrators shall be of a type and design approved by the Engineer. They shall

be capable of transmitting vibration to the concrete at frequencies of not less than

4,500 impulses per minute.

3) The intensity of vibration shall be such as to visibly affect a mass of concrete

of 20 mm slump over a radius of at least 450 mm.

4) The Contractor shall provide a sufficient number of vibrators to properly

compact each batch immediately after they are placed in the forms.

5) Vibrators shall be manipulated to thoroughly work the concrete around the

reinforcement and embedded fixtures, and into the corners and angles of the forms.

Vibration shall be applied at the point of deposit and in the area of freshly deposited

concrete. The vibrators shall be inserted and withdrawn from the concrete slowly.

The vibration shall be of sufficient duration and intensity to thoroughly compact the

concrete, but shall not be continued so as to cause segregation. Vibration shall not be

continued at any one point to the extent that localized areas of grout are formed.

Application of vibrators shall be at points uniformly spaced and not further apart

than twice the radius over which the vibration is visibly effective.

6) Vibration shall not be applied directly or through the reinforcement to

sections or layers of concrete which have hardened to the degree that the concrete

ceases to be plastic under vibration. It shall not be used to make concrete flow in the

forms over distances so great as to cause segregation, and vibrators shall not be used

to transport concrete in the forms.

7) Vibration shall be supplemented by such spading as is necessary to ensure

smooth surfaces and dense concrete along form surfaces and in corners and locations

impossible to reach with the vibrators.


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8) The provisions of this Section shall also apply to precast piling, concrete

cribbing and other precast members except that, if approved by the Engineer, the

manufacturer’s methods of vibration may be used.

Concrete shall be placed in horizontal layers not more than 600 mm thick except as

hereinafter provided. When less than a complete layer is placed in one operation, it

shall be terminated in a vertical bulkhead. Each layer shall be placed and compacted

before the preceding batch has taken initial set to prevent injury to the green

concrete and avoid surfaces of separation between the batches. Each layer shall be

compacted so as to avoid the formation of a construction joint with a preceding layer

which has not taken initial set.

When the placing of concrete is temporarily discontinued, the concrete, after

becoming firm enough to retain its form, shall be cleaned of laitance and other

objectionable material to a sufficient depth to expose sound concrete. To avoid

visible joints as far as possible upon exposed faces, the top surface of the concrete

adjacent to the forms shall be smoothed with a trowel. Where a “feather edge” might

be produced at a construction joint, as in the sloped top surface of a wing wall, an

inset form shall be used to produce a blocked out portion in the preceding layer

which shall produce an edge thickness of not less than 150 mm in the succeeding

layer. Work shall not be discontinued within 450 mm of the top of any face, unless

provision has been made for a coping less than 450 mm thick, in which case, if

permitted by the Engineer, a construction joint may be made at the underside of the

coping.

Immediately following the discontinuance of placing concrete all accumulations of

mortar splashed upon the reinforcement steel and the surfaces of forms shall be

removed. Dried mortar chips and dust shall not be puddle into the unset concrete. If

the accumulations are not removed prior to the concrete becoming set, care shall be

exercised not to injure or break the concrete-steel bond at and near the surface of the

concrete, while cleaning the reinforcement steel.

For simple spans, concrete shall preferably be deposited by beginning at the centre

of the span and working from the centre toward the ends. Concrete in girders shall

be deposited uniformly for the full length of the girder and brought up evenly in

horizontal layers. For continuous spans, the concrete placing sequence shall be as

shown on the plans or agreed on by the Engineer.


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Concrete in slab and girder haunches less than 1 .0 Meter in height shall be placed at

the same time as that in the girder stem.

Concrete in slab spans shall be placed in one continuous operation for each span

unless otherwise provided.

Concrete in T-beam or deck girder spans may be placed in one continuous operation

if permitted by the Engineer.

Concrete in columns and pier shafts shall be placed in one continuous operation,

unless otherwise directed.

Unless otherwise permitted by the Engineer, no concrete shall be placed in the

superstructure until the column forms have been stripped sufficiently to determine

the character of the concrete in the columns. The load of the superstructure shall not

be applied to the supporting structures until they have been in place at least 14 days,

unless otherwise permitted by the Engineer.

Pneumatic placing of concrete shall be permitted only if authorized by the Engineer.

The equipment shall be so arranged that vibration does not damage freshly placed

concrete.

Where concrete is conveyed and placed by pneumatic means the equipment shall be

suitable in kind and adequate in capacity for the work. The machine shall be located

as close as practicable to the place of deposit. The position of the discharge end of the

line shall not be more than 3 Meters from the point of deposit. The discharge lines

shall be horizontal or inclined upwards from the machine. At the conclusion of

placement the entire equipment shall be thoroughly cleaned.

Placement of concrete by pumping shall be permitted only if authorized by the

Engineer. The equipment shall be so arranged that vibrations do not damage freshly

placed concrete. Where concrete is conveyed and placed by mechanically applied

pressure, the equipment shall be suitable in kind and adequate in capacity for the

work. The operation of the pump shall be such that a continuous stream of concrete

without air pockets is produced. When pumping is completed, the concrete

remaining in the pipeline, if it is to be used, shall be ejected in such a manner that

there is not contamination of the concrete or separation of the ingredients. After this

operation, the entire equipment shall be thoroughly cleaned.


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3.1.4.7 Perforations and Embedment of Special Devices

The Contractor is responsible for determining in advance of making any concrete

pours, all requirements for perforation of concrete sections or embedment therein of

special devices of other trades, such as conduits, pipes, weep holes, drainage pipes,

fastenings, etc. Any concrete poured without prior provision having been made,

shall be subject to correction at the Contractor’s expense.

Special devices to be embedded:

Expansion joints

Drain outlets including fixing bolts for down pipes

Bolts and inserts for sign posts

Bolts and inserts for various purposes regarding inspection and maintenance as directed by the Engineer

Other devices not mentioned above shall be shown on the Drawings, or directed by

the Engineer.

3.1.4.8 Finishing Concrete Surfaces

One of the following types of finishing shall be applied to concrete surfaces:

Type A - Concrete Decks

Immediately after placing concrete, concrete decks shall be struck off using

templates to provide proper crowns and shall be finished smooth to the correct

levels. Finish shall be slightly but uniformly roughened by brushing. The finished

surface shall not vary more than 10 mm from a 3 Meter straight edge placed in any

direction on the roadway. Deviation from the grade line shall not be more than + 30

mm in any 20 Meter length.

Type B - Kerb and Sidewalk Surface

Exposed faces of kerbs and sidewalks shall be finished to true lines and grades. The

kerb surface shall be wood floated to a smooth but not slippery finish. Sidewalk

surfaces shall be slightly but uniformly roughened by brushing.


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Type C - Ordinary Finish

An ordinary finish is defined as the finish left on a surface after the removal of the

forms when all holes left by form ties have been filled, and any minor surface defects

have been repaired. The surface shall be true and even, free from depressions or

projections.

The concrete in bridge seats, caps, and tops of walls shall be struck off with a straight

edge and floated to true grade. Under no circumstances shall the use of mortar

topping for concrete surfaces be permitted.

Type D - Rubbed Finish

After the removal of forms the rubbing of concrete shall be started as soon as its

condition permits. Immediately before starting this work the concrete shall be kept

thoroughly saturated with water for a minimum period of three hours. Sufficient

time shall have elapsed before the wetting down to allow the mortar used in

patching to have thoroughly set. A medium coarse carborundum stone shall be used

for rubbing a small amount of mortar on the face. The mortar used shall be

composed of cement and fine aggregate mixed in the same proportions as that used

in the concrete being finished. Rubbing shall be continued until all form marks,

projections, and irregularities have been removed, all voids filled, and a uniform

surface has been obtained. The paste produced by this rubbing shall be left in place

at this time. The final finish shall be obtained by rubbing with a fine carborundum

stone and water until the entire surface is of a smooth texture and uniform color.

After the final rubbing has been completed and the surface has dried, burlap shall be

used to remove loose powder. The final surface shall be free from unsound patches,

paste, powder and objectionable marks.

Type E – Bush hammer Finish

Bush hammering shall be carried out by treating the surface with an approved heavy

duty power hammer fitted with a multi-point tool which shall be operated over the

surface to remove 5 to 6 mm of concrete paste and expose maximum areas of coarse

aggregate.


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Aggregate left embedded shall not be fractured or loose. 25 mm wide bands at all

corners and arises shall be left as cast. The finish surface shall be even and of

uniform appearance and shall be washed with water upon completion.

Type F - Ribbed Finish

Ribs shall be vertical and to the dimensions shown on the Drawings. The direction of

the grain of the timber forming the ribs shall be vertical.

3.1.4.9 Construction Joints

A) General

Construction joints shall be made only where located on the plans or shown in the

pouring schedule, unless otherwise approved by the Engineer.

If not detailed on the plans, or in the case of emergency, construction joints shall be

placed as directed by the Engineer. Shear keys or inclined reinforcement shall be

used where necessary to transmit shear or bond the two sections together.

B) Bonding

Before depositing new concrete on or against concrete which has hardened, the

forms shall be re-tightened. The surface of the hardened concrete shall be roughened

as required by the Engineer, in a manner that does not leave loosened particles of

aggregate or damaged concrete at the surface. It shall be thoroughly cleaned of

foreign matter and laitance, and saturated with water. To ensure an excess of mortar

at the juncture of the hardened and the newly deposited concrete, the cleaned and

saturated surfaces, including vertical and inclined surfaces, shall first be thoroughly

covered with a thin coating of mortar or neat cement grout against which the new

concrete shall be placed before the grout has attained its initial set.

The placing of concrete shall be carried continuously from joint to joint. The face

edges of all joints which are exposed to view shall be carefully finished true to line

and elevation.


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3.1.4.10 Curing Concrete

All concrete surfaces shall be kept thoroughly wet for at least 7 days after placing.

Bridge deck and sidewalk slabs shall be covered with wet hessian immediately after

final finishing of the surface. This material shall remain in place for the full curing

period or may be removed and replaced with sand when the concrete has hardened

sufficiently to prevent marking. In both cases the materials shall be kept thoroughly

wet for the entire curing period. All other surfaces if not protected by forms, shall be

kept thoroughly wet, either by sprinkling or by the use of wet burlap until the end of

the curing period. The wood forms are allowed to remain in place during the curing

period, but they shall be kept moist at all times to prevent openings at joints.

After a period of 7 days, the concrete shall be watered daily at certain intervals

approved by the Engineer to avoid drying out of the surface. This shall take place

during the following 2 weeks. The water used shall be the same as used in concrete

mixes unless otherwise approved by the Engineer.

Any proposal from the Contractor for the use of liquid membrane curing compound

shall be subject to the approval of the Engineer.

3.1.4.11 Removal of Scaffolding and Formwork

Forms and scaffolding shall not be removed without the approval of the Engineer.

The Engineer’s approval shall not relieve the Contractor of his Contract

responsibilities. Any kentledge blocks and bracing shall be removed at the same time

as the forms and in no case shall any portion of the wood forms be left in the

concrete.

Forms used on exposed vertical faces shall remain in place for periods which shall be

determined by the Engineer and normally not less than 3 days.

Supporting scaffolding and forms under slabs, beams and girders shall normally

remain in place until the full required strength of the concrete has been obtained. If a

shorter period is requested, this may be permitted by the Engineer. In such case,

special test specimens (see Section 3.1.3.4) shall be cast to monitor the hardening.

All structures shall be fully stripped before adjacent structures are cast.


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3.1.4.12 Repair of Concrete

As soon as the form has been stripped, the Contractor shall advise the Engineer who

shall inspect the concrete before any improvement of the surface takes place.

All wire or metal devices used for securing the formwork which project from or

appear on the surface of the finished concrete shall be removed or cut back to at least

a depth equal to the required reinforcement cover. All holes and pockets so formed

shall be filled with cement mortar mixed in the same proportions as the fine

aggregate to cement of the concrete mix used for that particular section of the

structure, after the surface to be patched has been thoroughly cleaned and wetted to

receive the patch.

Excessive honeycombing shall be sufficient to cause rejection of portions of the

structure containing this honeycombing. The Contractor, on receipt of written orders

from the Engineer, shall remove and rebuild such portions of the structure at his

own expense.

Smaller honeycombing and other defects can be repaired if permitted by the

Engineer. Structural, maintenance and aesthetical points of view shall be taken into

consideration before such approval, if any, may be given. The method of repair shall

be approved by the Engineer and an extension of period for a certain part of the

performance bond may be required.

3.1.4.13 Depositing Concrete under Water

Concrete shall not be deposited in water except with the approval of the Engineer

and under his immediate supervision; and in this case the method of placing shall be

as defined in this Section.

Concrete placed under water shall be carefully placed in a compact mass, in its final

position, by means of a tremie tube and shall not be disturbed after being deposited.

Special care must be exercised to maintain still water at the point of deposit.

Concrete shall not be placed in running water. The method of depositing concrete

shall be so regulated as to produce approximately horizontal surfaces.

Concrete seals shall be placed in one continuous operation. When a tremie tube or

pipe is used, it shall consist of a tube or pipe not less than 150 mm in diameter. All

joints in the tube shall be watertight. The means of supporting the tremie tube shall

be such as to permit free movement of the discharge end over the entire top of the


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concrete and to permit its being lowered rapidly when necessary to choke off or

retard the flow. The tremie tube shall be filled by a method that prevents washing of

the concrete. The discharge end shall be completely submerged in concrete at all

times and the tremie tube shall be kept full. Concrete slump shall not be less than 150

mm.

Dewatering shall proceed only when the concrete seal is considered strong enough

to withstand any pressure to be exerted upon it. This time shall be decided by the

Engineer.

All laitance or other unsatisfactory material shall be removed from the exposed

surface by scraping, jetting, chipping or other means, which do not injure the seal

unduly.

3.1.4.14 Factory Made Precast Concrete Elements

Any supplier of precast concrete elements shall be approved in writing by the

Engineer. Such approval can be withdrawn at any time.

Concrete work in precast concrete elements shall fully conform to all relevant

Sections of these Specifications.

The supplier shall maintain laboratory facilities of the same standard as the site

laboratory.

Unless otherwise approved by the Engineer, precast concrete members shall not be

moved from the casting position until the concrete has attained a compressive

strength of 80% of the specified 28-day strength, nor transported until it has

developed strength of 90% of the specified 28-day strength.

Extreme care shall be exercised in handling and moving precast concrete members.

Precast girders and slabs shall be transported in an upright position. Shock shall be

avoided and the points of support and directions of the reactions with respect to the

member shall be approximately the same during transportation and storage as when

the member is in its final position. If the Contractor deems it expedient to transport

or store precast units in other than this position, this shall be at the Contractor’s risk,

after notifying the Engineer of his intention to do so. Any rejected unit shall be

replaced at the Contractor’s expense by an acceptable unit.


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Proposed details on the handling and transportation of precast concrete members

shall be submitted in writing by the Contractor, to the Engineer, for his approval.

Each precast member is to be uniquely and permanently marked so as to show its

type, date of casting and any other information required by the Engineer.

3.1.4.15 Control of Heat in Structures

In structures of major dimensions i.e., pile caps, etc. the heat deriving from the

hardening of the concrete shall be controlled by the Contractor. Temperature

gradients introducing risk of cracking shall not occur and the temperature shall not

exceed 70°C.

The Contractor shall submit timely proposals for avoiding excessive heat generation,

such as the cooling of aggregates before mixing, to the Engineer for approval.

3.1.4.16 Loading

No superstructure load shall be placed upon finished bents, piers, or abutments until

the Engineer so directs but in no case shall any toad of any kind be placed until the

concrete has completed curing.

The Contractor shall not place any temporary loads on deck slabs unless allowed by

the Engineer in writing (see Section 3.2). Bridge deck slabs shall be opened to traffic

only when so directed by the Engineer and generally not sooner than 28 days after

the placing of the concrete has been completed.

3.1.4.17 Backfill to Structures

All spaces which have been excavated and the volumes of which are not occupied by

the concrete structure shall be backfilled and compacted with acceptable material in

accordance with the provisions of relevant specification and as directed by the

Engineer. Cleaning Up

Upon completion of a structure and before final acceptance, the Contractor shall

remove all forms and scaffolding etc. down to 0.5 Meters below the finished ground

line. Excavated, or useless materials, rubbish etc. shall be removed from the Site and

the Site shall be left in a neat and tidy condition satisfactory to the Engineer.


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3.1.5 Measurement

Concrete shall be measured by the number of cubic Meters of Class indicated on the

Drawings complete in place and accepted by the Engineer. In computing quantities,

the dimensions used shall be those shown on the Drawings. No deduction from the

measured quantity shall be made for drainage, pipes less than 300 mm in diameter,

conduits, chamfers, reinforcement bars, expansion joints, water stops or pile heads

embedded in concrete.

Reinforcing steel shall be measured for payment as described in Specifications

Sections 3.3.

3.1.6 Payment

The concrete of grades shown on the Drawings and measured as provided in Section

3.1.5 shall be paid for at the Contract unit prices per cubic Meter. The Contractor’s

rates shall include materials, mixing, transporting, placing and compacting the

concrete. The rates shall also include all trial mixes (as specified in Section 3.1.3.3), all

conformance tests, all concrete finishing, the supply, placing and building in of weep

pipes or pipe sleeves, forming construction joints, forming holes or pockets not

exceeding 0.15 m3 each.

Payment for precast units shall include all concrete, formwork, finishing, transport

and erection and where applicable any bolts, bedding or other devices necessary to

fix them in their permanent position.

3.1.7 Pay Items

1) Providing and laying leveling concrete in Plain Cement Concrete of grade as Detailed on the Drawings and as stated in the Bill of Quantities (BoQ) for all the foundations m3 of the bridge

2) Providing and laying Reinforced Cement Concrete (RCC)

of grade as detailed in the drawings and as stated in the BoQ for Abutments A1 & A2:

a) Footing slabs of the abutments m3 b) Abutment walls (stem), dirt walls & return walls

including supply, placing and building in of the weep pipes as per details shown in the relevant drawings. m3


Page | 70 of 112


of grade as detailed in the drawings and as stated in the BoQ for Piers P1, P2 & P3:

a) Footing slabs of the piers m3 b) Pier column (stem) and pier cap/ beam including supply

and placing as per details shown in the relevant drawings. m3

4) Providing and laying Reinforced Cement Concrete (RCC) of grade as detailed in the drawings and as stated in the BoQ for the main girders and cross girders. m3


of grade as detailed in the drawings and as stated in the BoQ for the connecting slab and concrete at joints on the piers. m3


of grade as detailed in the drawings and as stated in the BoQ for the deck slab and kerb beams. m3


of grade as detailed in the drawings and as stated in the BoQ for the approach slabs. m3

8) Manufacturing and placing of reinforced precast concrete footpath

slabs of grade as detailed in the drawings and as stated in the BoQ. pcs.

3.2 FORMWORKS AND SCAFFOLDING

3.2.1 Scaffolding (Falsework)

Details, plans and structural calculations for scaffolding shall be submitted by the

Contractor to the Engineer for approval, but in no case shall the Engineer’s approval

relieve the Contractor of his contract responsibilities. All scaffolding shall be

designed and constructed by the Contractor to provide the necessary rigidity and to

support dead and live loads without deflection or deformation. The Engineer may

require the Contractor to employ screw jacks or hardwood wedges to take up any

settlement in scaffolding and formwork, either before or during the placing of

concrete.


Page | 71 of 112

Tests may be required by the Engineer of materials proposed by the Contractor for

scaffolding. Test loadings of the completed scaffolding may also be required for the

determination of flexibility and strength. All expenses associated with testing shall

be borne by the Contractor.

Scaffolding which cannot be founded on a satisfactory footing shall be supported on

piles, which shall be spaced, driven and removed in a manner approved by the

Engineer. When the Contractor wishes to support scaffolding on existing structures,

he shall submit his proposals in due time to the Engineer, in writing, including loads

from the scaffolding. The Engineer will consider the proposals and respond in

writing.

Scaffolding shall be set to give the finished structure a camber, if indicated on the

Drawings or specified by the Engineer.

Scaffolding shall remain in place for periods which shall be determined by the

Engineer.

The formwork shall be properly designed for the self-weight, weight of

reinforcement, weight of fresh concrete, various live loads imposed during the

construction process (such as workmen and equipment). Dumping of concrete,

movement of construction equipment and action of the wind may produce lateral

forces which must be resisted by the form work to prevent lateral failure for which

suitable horizontal as well as diagonal bracings shall be provided. The permissible

stresses in bending, buckling load of props, permissible deflection of shuttering

should not be exceeded.

In case the height of centering exceeds 3.50 Meters, the props may be provided in

multi-stages.

Before the concreting is started, the props and wedges shall be thoroughly checked

to see that these are intact, and take suitable action in case these are loose. While the

concreting is in progress, at least one carpenter shall be readily available at the site.

The carpenter shall keep a constant watch on the props and take immediate remedial

measures, as soon as any of these get loosened. Care shall be taken that props and

wedges do not get loose for a minimum period specified in Table 3.2-1.


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3.2.2 Formwork

Formwork shall include all temporary or permanent moulds for forming the

concrete. Formwork shall be of wood, metal or other approved materials and shall

be built mortar tight and rigid enough to maintain the concrete in position during

placing, compacting, setting and hardening.

Formwork for exposed surfaces (“wrought form”) shall be made of dressed lumber

of uniform thickness with or without a form liner of an approved type or shall be of

metal sufficiently rigid in itself with no surface blemishes that will impair the quality

of the concrete surface finish. No rusty or bent metal forms shall be used. Exposed

concrete arises shall be provide with formed chamfers, as indicated on the Drawings

or instructed by the Engineer.

Rough lumber may be used for surfaces that will not be exposed in the finished

structure (“rough form”).

All lumber shall be sound, free from warps and twists, sap, shakes, large or loose

knots, wavy edge or other defects affecting the strength or appearance of the

finished structure.

All forms shall be set and maintained true to the line designated until the concrete is

sufficiently hardened. Forms shall remain in place for periods, which shall be

determined by the Engineer. When forms appear to be unsatisfactory in any way,

either before or during the placing of concrete, the Engineer may order the work

stopped until the defects are corrected.

If requested, the Contractor shall submit to the Engineer working drawings of the

forms and also, if requested, calculations to verify the rigidity and strength of the

forms.

The shape, strength, rigidity, water tightness and surface smoothness of reused

formwork shall be maintained at all times. Any warped or bulged lumber must be

re-sized before being reused. Formwork that is unsatisfactory in any respect shall not

be reused.

Metal ties or anchorages within the form shall be so constructed as to permit their

removal to a depth of at least 50 mm from the face without injury to the concrete. All

fittings for metal ties shall be of such design that, upon their removal, the cavities


Page | 73 of 112

which are left will be of the smallest possible size. The cavities shall be filled with

cement mortar and the surface left sound, smooth, even and uniform in color.

Formwork shall be so constructed that easy cleaning out of any extraneous material

inside the formwork can be achieved without disturbing formwork already checked

and approved by the Engineer.

Formwork shall be treated with approved non-staining oil or saturated with water,

to facilitate formwork removal. The Engineer may require trials to be carried out

before approval is given for the use of a particular type of oil, to ascertain that the oil

proposed by the Contractor does not discolor or injure the finished concrete face in

any way.

Before placing any concrete, all shavings, loose binding wires, soil, rubbish and all

foreign matter shall be removed from the formwork and the formwork shall be

carefully and thoroughly washed with water. If not indicated otherwise, the

following tolerances of the finished concrete structures shall apply:

Foundations: horizontally ±30 mm; vertically ±20 mm

Piers: Horizontally±20 mm, vertically~ 10mm, inclination 1:400

Dimensions of other structural members: + 10 mm, -5 mm

Edge beams and parapets shall be made to such accuracy that no deviations from the

correct alignment are visible.

The cross sectional areas of the superstructure of bridges shall in no place deviate

more than 3% from the theoretically correct cross sectional areas.

Anchors for bearings, expansion joints, railings, etc. shall be placed within the

tolerances indicated on the Drawings or specified by the Engineer.

3.2.2.1 Surface Treatment for Shuttering

The surfaces of timber shuttering that would come in contact with concrete shall be

well wetted and coated with soap solution, raw linseed oil or form oil of approved

manufacture, to prevent adhesion of concrete to form work. Use of polythene sheets

shall not be permitted. Soap solution, for the purpose shall be prepared by

dissolving yellow soap in water to get the consistency of paint. Inside surfaces of


Page | 74 of 112

forms shall be thoroughly cleaned before application of any of the materials

mentioned above. Release agents shall be applied strictly in accordance with the

manufacturers’ instructions and shall not be allowed to come in contact with any

reinforcement. Re-use of the shuttering shall be permitted only after the inside

surface has been thoroughly cleaned in the manner described above.

Contractor shall give the Engineer due notice before placing any concrete in the

forms to permit him to inspect and accept the form work as to its strength alignment

and general fitness, but such inspection shall not relieve the contractor of his

responsibility for safety of workman, machinery, materials and for results obtained.

3.2.2.2 Camber

Cambers both along and across the bridge shall be provided as per the lines and

levels shown in the design drawings or as directed by the Engineer. The scaffold and

the formwork shall be so assembled as to provide for such camber. For cantilevers,

the camber at free end shall be 1/50th of the projected length or as directed by the

Engineer.

3.2.3 Approval of Scaffolding and Formwork

If plans and calculations of scaffolding and formwork are sought by the Engineer, no

construction of such scaffolding and formwork shall take place before approval by

the Engineer, in writing. Such approval shall not relieve the Contractor of his

responsibilities under the Contract for the adequacy of scaffolding and formwork.

The Engineer shall have reasonable time for his examination of the Contractor’s

plans and calculations, especially if scaffolding is introducing temporary loading on

new structures. The Contractor shall not be allowed extensions of Contract time due

to awaiting such approval.

The Engineer shall inspect all formwork and scaffolding and no concrete shall be

placed until the Engineer’s approval has been given. Such approval shall not relieve

the Contractor of any of his responsibilities under the Contract for the successful

completion of the structure.

3.2.4 Special Formwork

For special type of work-locations like tall structures etc. use of special types of

formwork like moving or climbing forms shall be permitted. The details of such


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formworks along with the sequence of working shall be approved by the Engineer

before their erection.

3.2.5 Removal of Form Work

No formwork or any part thereof shall be removed without prior approval of the

Engineer. The formwork shall be so removed as not to cause any damage to concrete

due to shock or vibration. In a slab and beam construction, sides of beam shall be

stripped first, then the under sides of slab and lastly the underside of the beam.

Formwork must be so designed that they can be stripped in the order required i.e.

(a) Shutters to vertical (non load bearing) faces e.g. column boxes, beam sides, wall

forms,

(b) Shutters forming soffits to slabs, horizontal and inclined which carry only light

load, e.g. slabs, roofs, floors and canopies etc.

(c) Soffit shutters carrying heavy load e.g. beam and girder bottoms.

The whole of the formwork should be planned and a definite scheme of operation

worked out. In no circumstances should forms be struck until the concrete reaches

strength of at least twice the stress to which the concrete may be subjected at the

time of striking. Where possible the formwork should be left longer as it would

assist curing. Forms should be eased carefully in order to prevent the load being

suddenly transferred to concrete. The period that shall elapse after the concrete has

been laid, before easing and removal of centering and shuttering is undertaken shall

be as given in Table 3.2-1 below:

Table 3.2-1 Removal of Form Work

Type of formwork

Minimum period before striking

formwork

Vertical formwork of Column, Wall and beams

16 – 24 h

Soffit formwork to slabs ( props to be re-fixed immediately after removal of formwork)

3 days

Soffit formwork to beams ( props to be 7 days


Page | 76 of 112

Type of formwork

Minimum period before striking

formwork

re-fixed immediately after removal of formwork)

Props to deck slabs spanning upto 4.5 m

7 days

Props to deck slabs spanning over 4.5 m

14 days

Props to beams spanning upto 6m

14 days

Props to beams and arches spanning over 6 m

21 days

Note 1: In case of cantilever slabs and beams, the centering shall remain till structures for

counter acting or bearing down have been erected and have attained sufficient strength.

Note 2: Proper precautions should be taken to allow for the decrease in the rate of hardening

that occurs with all cements in cold weather.

Note 3: Work damaged through premature or careless removal of forms shall be

reconstructed.

3.2.6 Measurements

The formwork shall be paid for separately. Measurement shall be taken of the area of

shuttering in contact with the concrete surface.

Dimensions of formwork shall be measured correct to 10mm. The measurements

shall be taken separately under each of the items mentioned in the Pay Item.

No deductions from the shuttering due to the openings/ obstructions shall be made

if area of such openings/obstructions does not exceed 0.1sq.m. Nothing extra shall

be paid for forming such openings.

3.2.7 Payment

The rate of formwork includes the cost of planning & design of a safe scaffold

system, material, erection, centering & propping, shuttering and formwork and

other materials, tools and plant, labor required for all the operations described in this

section including properly supporting the members as required until the concrete is


Page | 77 of 112

cured, set and hardened as required. No separate payment shall be made for items

such as form release agent, connections, ties, provisions for openings and other items

required for the completion of the work unless specified otherwise.

3.2.8 Pay Items

9) Centering and shuttering for abutments A1 & A2 including all scaffolds and propping works:

a) The sides of footing slabs of the abutments m2 b) Abutment walls (stem), dirt walls & return walls m2

10) Centering and shuttering for piers P1, P2 & P3 including

all scaffolds and propping works:

a) The sides of footing slabs of the piers m2 b) Pier column/ stem and pier cap/ beam m2

11) Centering and shuttering for the main girders and cross girders including all scaffolds and propping works, etc. required to support the shuttering:

a) The formwork for the main girders. m2 b) The formwork for the cross girders. m2

12) Centering and shuttering for the deck slab including all scaffolds

and propping works, etc. required to support the shuttering: m2 13) Centering and shuttering for the kerb beam including all

propping works, etc. required to support the shuttering: m2

14) Centering and shuttering for the approach slab including all propping works, etc. required to support the shuttering: m2

3.3 REINFORCEMENT

3.3.1 Description

This work shall consist of furnishing and placing bars of the grade, type and size in

accordance with this specification and the BoQ and in conformity with the

requirements shown in the Drawings.


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3.3.2 Materials

3.3.2.1 Bar Reinforcement

All high yield steel bars shall be deformed bars with a yield stress not less than 500

N/mm2 and shall conform to Indian Standard IS:1786 or specification in force that is

considered by the Engineer to apply.

The use of cold twisted bars is not permitted. Steel for all bars shall be produced by

open hearth, basic oxygen or electric arc furnace methods, unless otherwise called

for on the Drawings or in special provisions.

3.3.2.2 Wire Mesh

Wire mesh shall conform to the requirements of Indian Standard IS 1566 [or

AASHTO Standard Specification M 55 -Welded Steel Wire Fabric for Concrete

Reinforcement or ASTM A185 / A185M – 07].

3.3.2.3 Binding Wire

Reinforcement binding wire shall be best black annealed mild steel wire,

approximately 1.6 mm in diameter.

3.3.2.4 Bar Sizes

Metric sizes of steel are shown on the Drawings and shall be used.

3.3.2.5 Ordering Material

The name of the proposed supplier (or names of proposed suppliers) of the

reinforcement shall be submitted as soon as possible to the Engineer for his

approval. The Contractor shall also submit all relevant data on the steel required by

the Engineer, such as breaking strength, yield strength, characteristics on elongation,

chemical composition, etc.

Copies of orders placed shall be submitted to the Engineer.

No steel shall be delivered without a manufacturer’s certificate guaranteeing the

yield stress, which shall be submitted to the Engineer.

The steel shall be stored on Site and marked in a way that later enables identification

of the steel corresponding to each certificate.


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3.3.2.6 Additional Tests

The Contractor shall cut out steel samples as directed by the Engineer and these shall

be tested according to the Engineer’s instructions by an approved Testing Institution.

Expenses incurred in connection with cutting out, transporting and testing of the

samples shall be paid for by the Contractor. In general, two samples shall be tested

from each batch of a particular size of reinforcement delivered to the site.


3.3.3.1 Protection and Storage

Reinforcement for structures shall be handled and stored in a manner that will

prevent bending out of the desired shape and any accumulation of dirt, oil and

paint. When placed in the works it shall be free from dirt, oil, grease, paint, mill scale

and loose or thick rust.

3.3.3.2 Cutting and Bending

Bars shall be cut and bent cold to the dimensions indicated and with equipment and

methods approved by the Engineer.

Stirrups and tie bars shall be bent around a pin having a diameter not less than four

times the minimum thickness of the bar. Bends for other bars, where full tension in

the bar may occur, shall be made around a pin having a diameter not less than

twenty times the bar diameter. Hooks shall conform to IRC:112 - 2011 or as shown in

the Drawings.

3.3.3.3 Placing, Supporting and Fastening

All bar reinforcement shall be placed, supported and secured prior to any concreting

operations. The reinforcement shall be checked and approved by the Engineer before

pouring of concrete.

Cover blocks required for ensuring that the reinforcement is correctly positioned

shall be as small as possible, consistent with their purpose, of a shape and material

acceptable to the Engineer, and designated so that they will not overturn when the

concrete is placed. If made of concrete, the maximum size of aggregate shall be 6 mm

and the mix proportion shall be one part of cement to 2 parts of sand by weight.

Wire shall be cast in the block for the purpose of tying it to the reinforcement. The


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wire must not be closer than 30 mm from the concrete surface. The use of small

stones or wood blocks shall not be permitted.

The reinforcement shall be held securely in place at the exact position and at the

exact spacing as indicated on the Drawings by the use of wire ties at bar

intersections, supports and cover blocks. Wire ties shall be securely tied and folded

so that they do not project beyond the planes formed by the reinforcing bars. The

adequacy of the supports and ties to secure the reinforcement properly shall be

subject to the approval of the Engineer.

3.3.3.4 Splicing

Reinforcement shall be furnished in the lengths indicated on the Drawings. When

the Contractor wishes to use more splices than are indicated and/or necessary, the

Contractor shall furnish Working Drawings to the Engineer for approval in

accordance with the guidelines provided on the Contract Drawings. If such

additional splices are approved, the extra weight occasioned by such splices shall not

be included in the measurement of reinforcement for payment.

All splices for high yield deformed steel bars and mild steel plain steel bars shall

have lap lengths as shown on the Drawings. Lap splices shall generally be located at

points of minimum tension in bars. Except where otherwise shown on the Drawings

lap splices shall be made with the bars placed in contact and securely wired together.

Welding of reinforcing steel shall be done only if detailed on the Drawings or

approved in writing by the Engineer. Before the Engineer may approve of such

welding, the Contractor shall submit and test any samples as the Engineer may

require and make due allowance for the time elapsing before results are available.

3.3.3.5 Substitutions

Substitutions of bars shall be permitted only with specific authorization by the

Engineer and at the expense of the Contractor. If bars are substituted they shall have

a cross sectional area equivalent to the design area, or larger. If substitutions of bars

are permitted, the Contractor shall produce working drawings and reinforcing

detailing at his own expense and to the approval of the Engineer. Substituted bar

must be tested as per requirement of the Engineer.


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3.3.4 Measurement

The quantity of reinforcement to be measured under this Section shall be the

computed weight in kg of material used and accepted as shown on the Drawings

provided that the quantity shall not include the reinforcement in any item of work

for which the basis of payment includes the reinforcement. In computing the weight

to be measured, the theoretical weights of bars of the cross section shown on the

Drawings or authorized shall be used. The weight shall be calculated based on a

constant mass of 0.00785 kg/mm2 per Meter run.

The computed weight shall not include the extra material incurred when bars larger

than those specified are used, or the extra material necessary for splices when bars

shorter than those specified are used with the permission of the Engineer, or the

weight of any devices used to support or fasten the reinforcement in the correct

position including any necessary Chairs for Slab, Pile/Caisson Caps, Footing or any

other structural components. The quantity for the chairs/spacers shown in the

drawings and accounted for in the bar bending schedule are incorporated in the BoQ

and shall be paid for separately at the contract unit price

However, payment shall be allowed for lap splices not shown when the bars are

longer than 12 meters, only one lap splice per every 12 meters will be paid for and

where required as per construction condition and approved by the Engineer.

3.3.5 Payment

This work measured as provided above, shall be paid for at the Contract unit price

per kg of reinforcement of the particular type. The payment shall be full

compensation for furnishing, cutting, bending and placing reinforcement of any size

and for all labor, binding wire, equipment, spacer/chair required for placing of

reinforcement, tools and incidentals necessary to complete the work prescribed in

this Section.

3.3.6 Pay Items

15) Providing and laying High Yield Strength Deformed (HYSD) bars conforming to grade Fe500 as per IS: 1786 for the abutments; A1 and A2 kg

16) Providing and laying High Yield Strength Deformed (HYSD) bars conforming to grade Fe500 as per IS: 1786 for the piers;


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P1, P2 and P3 kg 17) Providing and laying High Yield Strength Deformed (HYSD) bars

conforming to grade Fe500 as per IS: 1786 for the main girders and cross girders kg

18) Providing and laying High Yield Strength Deformed (HYSD) bars conforming to grade Fe500 as per IS: 1786 for the deck slab and kerb beams kg

19) Providing and laying High Yield Strength Deformed (HYSD) bars

conforming to grade Fe500 as per IS: 1786 for the approach slabs kg

3.4 PRESTRESSING WORKS

3.4.1 Description

This work shall consist of furnishing and placing of pre-stressing cable of standard

specified with this specification and the BoQ and in conformity with the

requirements shown in the Drawings.

3.4.2 Materials

3.4.2.1 Prestressing Cable/Tendon

The prestressing cable shall be low relaxation 7-wire strands. The tendons shall be

standard 12T13 or equivalent with 12 strands per tendon. The tendons shall be grade

1860 MPa as per Euro norm 138-6/79 super with nominal section area of 100 mm2 or

Grade 270 K as per A.S.T.M A416/80 with nominal section area of 98.7 mm2. The

sheathing duct for housing the tendons shall be corrugated HDPE ducts and shall

have diameter of 65 mm.

3.4.2.2 Ordering Material

The name of proposed supplier (or names of proposed suppliers) or the

manufacturers of the pre-stressing cable shall be submitted to the Engineer for the

approval. The contractor shall submit all the relevant data of the pre-stressing cable

required by the Engineer.


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3.4.3.1 Protection and Storage

The pre-stressing cable shall be stored in manner that it will not be rusted before

placing in the bridge. It shall be kept in such a way that its shape is not deformed

due to careless handling during the transportation and after reaching bridge site.

3.4.3.2 Placing, Positioning and Pre-stressing

The pre-stressing cable shall be placed and positioned as per the parabolic profile

maintained in the design drawings. The pre-stressing work shall be carried out by

specialist personnel with extensive knowledge and experience on the works of

similar nature. The tendons shall be tensioned symmetrically about the center line of

the girder. If the pre-stressing work is to be sub-contracted, the Contractor shall

obtain necessary approval from the Engineer before commencing the works.

3.4.3.3 Grouting

The grouting to fill the gap between pre-stressing cable and sheath shall be done in

such a way that no air voids is left. The air voids will cause rust to pre-stressing

cable and result in its deterioration before its service life.

3.4.4 Inspection and Quality control

The team of two Engineers from the Client shall inspect the pre-stressing

cable/tendons, sheathing ducts and other pre-stressing accessories at the

manufacturer’s yard before dispatch to the bridge site to check and confirm that the

pre-stressing cables and other accessories are manufactured as per the specifications.

Depending on the requirement, the inspection team will demand certain test to be

carried out on the materials in line with the provisions of the standard code of

practice. The Contractor/Supplier shall be obliged to carry out such tests and

verifications at no additional cost to the Client. The expenses for the factory visit

including travel (to and from air fare) and DSA as per RGoB rule shall be borne by

the contractor and therefore has to be accounted for while setting the rates.

3.4.5 Payment

This work measured as provided above, shall be paid for at the Contract unit price

per kilogram of pre-stressing tendon. The payment shall be full compensation for


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complete work done including the labor charge, factory inspection by Client, supply

of pre-stressing accessories and for tools and machineries involved to complete the

work prescribed in this Section.

3.4.6 Pay Item

20) Providing, placing of pre-stressing cables/tendons including its accessories and entire post-tensioning operation at site as per this specification and the drawings. Pre-stressing cable/tendons 12T13 or equivalent with 12 stands per tendon. kg


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SECTION 4

4.0 PERMANENT WORKS


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4.1 STONE MASONARY

4.1.1 Random Rubble Masonry

Providing & laying Random Rubble Masonry with hard stone in foundation & plinth SM0005 In cement mortar 1:4 SM0006 In cement mortar 1:5 SM0007 In cement mortar 1:6 SM0008 Hammer dressed, in mud mortar SM0017 Extra for random rubble masonry work with hard stone in square or rectangular pillars SM0018 Extra for random rubble masonry work with hard stone in circular pillars

4.1.2 Dressing:

Stones shall be hammer dressed, on the face, the sides and the beds, to enable it to

came intoclose proximity with the neighbouring stone. The bushing in the face shall

not project more than 4 cm in an exposed face, and one cm on a face to be plastered.

The hammer dressed stone shall have a rough tooling for a minimum width of 2.5

cm along the four edges of the face of stone.

4.1.3 Laying:

Every stone shall be carefully fitted to the adjacent stones, so as to form neat and

close joints. Stones may be brought to level courses at plinth, windowsills and roof

level. Levelling up at plinth level, window sills and roof level shall be done with

concrete comprising of one part of the mortar as used for the masonry and two parts

of graded stone aggregate of 20mm nominal size and shall be-included in the items.

The bond shall be obtained by fitting in closely, the adjacent stones and by using

bond-stones. Face stones shall extend and bond well into the backing. These shall be

arranged to-break joints as much as possible, and to avoid long vertical lines of

joints.

The hearting or interior filling of the wall shall consist of rubble stones, which may

be of any-shape but shall not pass through a circular ring of 15 cm inner diameter;

thickness of these stones in any direction shall not be less than 10 cm. These shall be

carefully laid, hammered down with a wooden mallet into position and solidly

bedded in mortar, chips and spalls of stone being used wherever necessary to avoid

thick mortar beds or joints and at the same time ensuring that no hollow spaces are


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left anywhere in the masonry. The hearting will Department of Engineering Services

be laid nearly level with facing and backing, except that at about one metre intervals,

vertical 'Plumb' projecting about 15 cm to 20 cm shall be firmly embedded to form a

bond between successive courses.

The chips shall not be used below the hearting stone to bring these upto the level of

face stones. The use of chips shall be restricted to the filling of interstices between the

adjacent stones in hearting, and then shall not exceed 20% of the quantity of stone

masonry. The masonry in a structure shall be carried regularly. Where the masonry

of one part has to be delayed the work shall be raked back at an angle not steeper

than 45 degree.

4.1.4 Bond Stones:

Bond or through stones running right through the thickness of walls, shall be

provided in walls upto 60 cm thick and in case of walls above 60 cm thickness, a set

of two or more bond stones overlapping each other by atleast 15 cm shall be

provided in a line from face to back.

In case of highly absorbent types of stones (porous lime stone and sand stone etc.)

the-bond stone shall extend about two- third into the wall. Through stones in such

cases may give rise to-damp penetrations therefore, for all thickness of such walls, a

set of two or more bond stones overlapping-each other by at least 15 cm shall be

provided. Where bond stone of suitable lengths are not available cement concrete

block of 1:3:6 mix (1 cement: 3 coarse sand: 6 graded stone aggregate 20 mm nominal

size) conforming to sizes mentioned above shall be used.

At least one bond stone or a set of bond stones shall be provided for every 0.5 sq.m

of the wall surface. All bond stones in stone masonry shall be marked suitably as

directed by the Engineer-in-charge.

4.1.5 Quoins or corner stone:

The quoins shall be of selected stones neatly dressed with the hammer and / or

chisel to form the required angle, and laid header and stretcher alternately. The

length of these stones shall be 45cm or more and at least 25% of the stones shall be

50cm or more in length.


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4.1.6 Jambs:

Stones used in jambs shall be similar to those in quoin, excepting the length of the

stem, which shall be 45cm, or thickness of the wall whichever is less.

4.1.7 Joints:

Stones shall be so laid that all joints are fully packed with mortar and chips. Face

joints shall not be thicker than 20 mm.When plastering or pointing is not required to

be done, the joints shall be struck flush and finished at the time of laying. Otherwise,

the joints shall be raked to a minimum depth of 20 mm by raking tool during the

progress of work, when the mortar is still green.

4.1.8 Scaffolding:

Single scaffolding having one set of vertical support shall be allowed. The supports

shall be sound and string tied together by horizontal pieces, over which the

scaffolding planks shall be fixed. The inner end of the horizontal scaffolding member

may rest in a hole provided in the masonry. Such holes, however, shall not be

allowed in pillars less than one metre in width or near the skew-back of arches. The

holes left in masonry work for supporting scaffolding shall be filled and made good

with cement concrete 1:3:6 (1 cement: 3 coarse sand: 6 stone aggregate 20 mm

nominal size).

4.1.9 Curing:

Masonry work in cement or composite mortar shall be kept constantly moist on all

face for a minimum period of seven days. In case of masonry with fat-lime mortar,

curing shall commence two days after laying of masonry and shall continue for at

least seven days thereafter.

4.1.10 Protection:

Green work shall be protected from rain by suitable covering. The work shall also be

suitably protected from damage, mortar dropping and rain during construction.

4.1.11 Measurement:

The length, height and thickness shall be measured correct to 10 mm. The thickness

of wall shall be measured at joints, excluding the bushings. Only specified


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dimensions shall be allowed; anything extra shall be ignored. The quantity shall be

calculated in cubic metre nearest to two places of decimal.

4.2 STONE SOLING, FILLING& EDGING

SM0070 Providing and laying Hammer dressed dry stone soling

SM0071 Providing and laying Chisel dressed dry stone soling

SM0072 Providing and laying Hand packed stone filling or soling with stones

Stones as obtained from the quarry shall be packed with their broader surface as

base. The packing shall be as dense as possible and the interstice shall be filled with

small stones. The height of stones shall be as per the thickness of soling required.

The stones shall be arranged neatly and the joints shall be as thin as possible.

4.2.1 Measurements:

The length, breadth and height shall be measured correct to 10 mm. and the volume

calculated correct to 0.01 cum.

4.2.2 Rate:

The rate shall include the materials and labour involved in all operation described

above.

4.2.3 Cement Plaster

Providing and laying 20mm cement plaster

PL0040 CM 1:3

PL0041 CM 1:4

PL0042 CM 1:5

PL0043 CM 1:6

4.2.4 Preparation of surface:

The joints shall be raked out properly. Dust and loose mortar shall be brushed out.

Efflorescence if any shall be removed by brushing and scraping. The surface shall

then be thoroughly washed with water, cleaned and kept wet before plastering is

commenced. In case of concrete surface, if a chemical retarder has been applied to

the formwork, the surface shall be roughened by wire brushing and all the resulting

dust and loose particles cleaned off and care shall be taken that none of the retarder

is left on the surface. The joints of masonry shall be raked out properly so that the

plaster is well keyed with the masonry.


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Mortar: The mortar of the specified mix described in the item shall be used.

Scaffolding: For all exposed brickwork or tile work, double scaffolding having two

sets of vertical supports shall be provided. The supports shall be sound and strong,

tied together with horizontal pieces over which scaffolding planks shall be fixed. For

all other masonry in buildings, single scaffolding shall be permitted. In such cases,

the inner end of the horizontal scaffolding pole shall rest in a hole provided only in

the header course for the purpose. Only

one header for each pole shall be left out. Such holes for scaffolding shall, however,

not be allowed in pillars/columns less than one metre in width, or immediately near

the skewbacks of arches. The holes left in masonry works for scaffolding purposes

shall be filled and made good before plastering.

Note: In case of special type of brickwork, scaffolding shall be got approved from

Engineer.

Application of Plaster:

Ceiling plaster shall be completed before commencement of wall plaster. Plastering

shall be started from the top and worked down towards the floor. All putlog holes

shall be properly filled in advance of the plastering as the scaffolding is taken down.

To ensure even thickness and true surface, plaster about 15 x 15 cm, shall be first

applied, horizontally and vertically, at not more than 2 metres intervals over the

entire surface to serve as gauges. The surfaces of these gauged areas shall be trulyin

the plane of the finished plaster surface. The mortar shall then be laid on the wall,

between the gauges with trowel. The mortar shall be applied in a uniform surface

slightly more than the specified thickness. The surface shall be brought to a true

surface, by working a wooden straight edge reaching across the gauges, with small

upward and side ways movements at a time. Finally the surface shall be finished off

true with trowel or wooden float accordingly as a smooth or a sandy granular

texture is required. Excessive trowelling or over working the float shall be avoided.

All corners, arises, angles and junctions shall be truly vertical or horizontal as the

case may be and shall be carefully finished. Rounding or chamfering corners,

junctions etc. where required shall be done without any extra payment. Such

rounding or chamfering shall be carried out with proper templates to the sizes

required. In suspending work at the end of the day, the plaster shall be left, cut clean

to line both horizontally and vertically, when recommencing the plastering, the edge

of the old work shall be scraped cleaned and wetted


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with lime putty or cement grout before plaster is applied to the adjacent areas, to

enable the two to properly join together. Plastering work shall be closed at the end of

the day on the body of the wall and not nearer than 15 cm to any corners or arises. It

shall not be closed on the body of the features such as plasters, bands and copings, as

these invariable lead to leakages. No portion of the surface shall be left out initially

to be patched up later on. The plastering and finishing shall be completed within

half an hour of adding water to the dry mortar.

4.2.5 Finish:

The plaster shall be finished to a true and plumb surface and to the proper degree of

smoothness as required. The work shall be tested frequently as the work proceeds

with a true straight edge not less than 2.5 m long and with plumb bobs. All

horizontal lines and surfaces shall be tested with a level and all jambs and corners

with a plumb bob as the work proceeds.

4.2.6 Precaution:

Any cracks which appear in the surface and all portions, which sound hollow when

tapped, or are found to be soft or otherwise defective, shall be cut out in rectangular

shape and redone as directed by the Engineer.

4.2.7 Thickness:

The thickness of the plaster specified shall be measured exclusive of the thickness of

key. The average thickness of the plaster shall not be less than the specified thickness

and the minimum thickness over any portion of the surface shall not be less than

specified thickness by more than 3 mm. Where the thickness required as per

description of the item is 20 mm the average thickness of the plaster shall not be less

than 20 mm whether the wall treated is of brick or stone. In the case of brickwork,

the minimum thickness over any portion of the surface shall not be less than 15 mm

while in the case of stonework the minimum thickness over the bushings shall be not

less than 12 mm.

4.2.8 Curing:

Curing shall be started as soon as the plaster has hardened sufficiently not to be

damaged when watered. The plaster shall be kept wet for a period of at least 7 days.

During this period, it shall be suitably protected from all damages at the contractor's

expense by such means as the Engineer may approve. The dates on which the


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plastering is done shall be legibly marked on the various sections plastered so that

curing for the specified period thereafter can be watched.

4.2.9 Measurement:

Length and breadth shall be measured correct to 10 mm and its area shall be

calculated in square metres correct to two places of decimal. Thickness of the plaster

shall be exclusive of the thickness of the key i.e. grooves, or open joints in brick

works. The measurements of wall plaster shall be taken between the walls or

partitions (the dimensions before plastering shall be taken) for the length, and from

the top of the floor or skirting to the ceiling for the height. Depth of coves or cornices

if any shall be deducted.

The following shall be measured separately from wall plaster:

a) Plaster bands 30 cm wide and under.

(b) Cornices, beadings and architraves or architraves moulded wholly in plaster.

(c) Circular work not exceeding 6 m in radius.Plaster over masonry pilasters will

be measured and paid for as plaster only. A coefficient of 1.63 shall be adopted for

the measurement of one side plastering on honeycomb work.Moulded cornices and

coves:

(a) Length shall be measured at the centre of the girth.

(b) Moulded cornices and coves shall be given in square metres the area being

arrived at by multiplying length by the girth.

(c) Flat or weather-top cornices when exceeding 15 cm in width shall not be

included in the girth but measured with the General Plaster work.

(d) Cornices, which are curved in their length, shall be measured separately.

Exterior plastering at a height greater than 10m from average ground level shall be

measured separately in each storey height. Patch plastering (in repairs) shall be

measured as plastering new work, where the patch exceeds 2.5 sq.m, extra payment

being made for preparing old wall, such as dismantling old plaster, raking out the

joints and cleaning the surface. Where the patch does not exceed 2.5 sq.m in area, it

shall be measured under the appropriate item under sub-head "Repairs to

Buildings".

Deductions in measurements for openings etc. will be regulated as follows:

(a) No deduction will be made for openings or ends of joists, beams, posts,

girders, steps etc. upto 0.5 sq.m in area; no additions shall be made either, for jambs,


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soffits and sills of such openings. The above procedure will apply to both faces of

wall.

(b) Deduction for openings exceeding 0.5 sq.m but not exceeding 3 sq.m each

shall be made for reveals, jambs, soffits, sills etc. of these openings.

(i) When both faces of walls are plastered with same plaster, deductions shall be

made for one face only.

(ii) When two faces of walls are plastered with different types of plaster or if one

face is plastered and other is pointed, or one face is plastered and other is un-

plastered, deduction shall be made from the plaster or pointing on the side of the

frame for the doors, windows etc. on which width of reveal is less than that on the

other side but no deduction shall be made on the other side. Where width of reveals

on both faces of wall are equal, deduction of 50% of area of opening on each face

shall be made from area of plaster and/or pointing as the case may be.

(iii) For opening having door frame equal to or projecting beyond thickness of

wall, full deduction for opening shall be made from each plastered face of wall.

(c) For opening exceeding 3 sq.m in area, deduction will be made in the

measurements for the full opening of the wall treatment on both faces, while at the

same time, jambs, sills and soffits will be measured for payment. In measuring

jambs, sills and soffits, deduction shall not be made for the area in contact with the

frame of doors, windows etc

4.2.10 Rate:

The rate shall include the cost of the labour and materials involved in all the

operations described above.

MINISTRY OF WORKS & HUMAN SETTLEMENT

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