Work Shop - Construction Materials Quality Control

8/3/2019 Work Shop - Construction Materials Quality Control

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www.unops.org

Construction Materials


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1. Fulfillment of Requirements

Material Requirements

Process Requirements Equipment Requirements

End Product Requirements

2. Fitness for Purpose

Riding comfort at design speed Ability to serve till the end of design life at design level of

serviceability

What is Quality in Construction?


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Quality is generally to mean compliance withspecified requirements

Quality control is a means to control quality i.e.to verify compliance of materials, equipment,process and final product to predetermined

requirements.


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Fine Aggregates (Sand)No. Inspection and TestingDescription

Testing

method

Acceptance criteria Frequency of Test

1

Grading

AASHTO T-27 Sieve(mm) % pass

10 100

4.76 95-100

2.38 68-861.19 47-65

0.59 27-42

0.3 9-20

0.15 0-7

0.075 0-2.5

One sample per 1500 m3

2 Soluble chlorides BS 812


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Rapid field Technique to Estimate silt content

River or pit sand shouldbe sharp, angular, hard,clean uncoated particles

free from clay andorganic impurities.

Well graded sand must beused for all cement work.


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Coarse Aggregate (Gravel)No. Inspection and Testing

Description

Testing method Acceptance criteria Frequency of Test

1Grading

AASHTO T-27 Different for different

nominal sizes

One sample per 1500 m3

2 LAA AASHTO T-96


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WaterNo. Inspection and Testing

Description

Testing method Acceptance criteria Frequency

of Test

1 Chloride content ASTM D 512


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Cement

No. Inspection and

Testing Description

Testing

method

Acceptance criteria Frequency

of Test

1cement

AASHTO T-

131

AASHTO M-85 Every lot

1.1 Consistency test AASHTO M-85 Every lot

1.2 Initial setting time AASHTO M-85 Every lot

1.3 Final setting time AASHTO M-85 Every lot

The cement to be used in the work should be ordinary Portlandcement complying with ASTM C-150 or BS-12.

Both Roads and Building specifications of UNOPS specify OPC,not PPC

Hardened cement will not be permitted in the works and is tobe removed from site at the contractors expense.


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Brick

Brick must have correct size, shape and sharp edges.

Bricks shall not break when dropped from 1m height, shall give ringingsound when struck with each other and leaves no impression withfinger nail

1. Mortar joint thickness shall not exceed 10mm in the class bricksand 12mm in second class bricks

2. Crushing strength (shall not be less than 35kg/sqcm for ordinarybricks) and water absorption (shall be less that 20%) waterabsorption dry the bricks and weigh (w1), immerse in water for24 hours and weigh again (W2). Then WA=(w2-w1)/W1*100 orA Brick shall not absorb more than 1/6th of its weight ofwater after being soaked for one hour

3. Bricks shall be soaked at least for 1 hour before use

4. Bricks work should be raised uniformly and height of work in a dayshall be less than 1.5m. Difference in height between two different

portions shall be less than 1m


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Shall be regular and uniform in size and shape with sharp square edges andparallel faces.

They shall be free from flaws, cracks and chips.

should have the following dimensions: 400mm x 200mm x 200mm.

There should be a longitudinal groove with 10mm depth and 20mm width oneach block in order to provide place forhorizontal steel reinforcement for themasonry work.

Sample shall be collected randomly and tested every 10m3 of blocks produced.Three samples (blocks) shall be selected at random from every batch.

The crushing strength of blocks shall be tested in a laboratory and the averagecrushing strength of blocks shall not be less than 15MPa (10 MPa) ??? (N/m2)and the water absorption of the blocks shall be not more than 240kg/m3 ofconcrete.

Blocks


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Timber shall be free from twists, knots, splits and other visual or physicaldefects

TIMBER


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Examples of Poor Materials


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Process Control

The assistant engineers shall always be at site to inspect and control thecontractors work processes.

Contractors always give priority for profit than for quality. Therefore, willgo for cheaper materials .

When you do process control, strictly ad

here to t

he Specifications

A number of factors should be controlled during construction as a vital partof process Control:

Material - is the contractor using approved material?

Mixing is the contractor using proper mix ratios? Proper mixingtechniques?

Moisture content is the contractor applying proper water content?Thickness / Lift what is the maximum thickness or lift specified forearth work, brick work, concreting etc?

Compaction what equipments are used during compaction?Whatare the number of passes?What is the sequence/direction passingduring compaction? etc

General finish what is the quality of the final product?


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Examples of Poor Process Control

Top soil and Overburden were notremoved properly due to weakness inprocess Control

Removal of overburden of the sameborrow pit after PM and ME instruction


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Poor Process Control Excessive material spreading with outclearing the road bed

The maximumallowed thicknesswas 200m

The road bedshould have beencleared properlybefore dumping


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Poor workmanship, Substandard work, and poor Masonrystones due to Poor Process Control during Culvert apron

construction


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Excessive Back Fill and Dry Compaction byContractor Lack of Process Control

Maximum allowed thickness of compaction at a time was 150mm butcontractor is filling 1000mm at a time

Contractor is supposed to apply optimum moisture to the back fill, but

prefer to compact it dry


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Improper Soaking of CBR test specimens Poor

Process Control


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End Product Specification

e.g. RoadIs the surface free from compaction planes, ridges, cracks, loose material andmovement under construction equipment?

Has the loose, segregate and otherwise defection areas made good to full depth?

Is the thickness of the layer in limits?The size of the coarse material does not exceed 2/3 of layer thickness?

Does the rolling pattern confirm to specification?

Does survey results conform confirm to requirements grade, cross fall, side ,surface levels, slopes etc

Moisture content prior to compaction ok?

Is Degree of Compaction acceptable?

Is the thickness as per the design?

Then Approve the layer!


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How can we control Quality of ConstructionMaterials in Particular and constructionactivities in General?

1. By Inspection and Process Observation

2. By Random sampling

3. By Testing

4. By Measuring


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InspectionInspection of Storage of Construction MaterialsSI. No Material/pr

oduct

Storage Precaution(Do`s and

Donts)`Location Method

1 Rebar open Store on timber

Runners or concretebeam

1. Dont mix different

dais.2. Cover with

polythene sheet in

rainy season

3. Dont block access

to vehicle

2 Cement Bag Shelteredstore Placed on pallets lifted300mm above ground. 1. Dont allow contact withmoisture or side walls

2. Dont exceed 12 bags

stacking

3 Concrete

pipes

Curing tank

for 7 days

Open Stack yard Proper ramp is made for

loading & unloading


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Testing/Inspection Item Yes No

Has the pipe culvert location been excavated as per the drawings

Have the bed levels of the excavation been checked as per the

drawings

Has the type of bedding specified in the drawing or ordered by the

engineer constructed

Is the manufactured or imported pipe culvert is as per the Technical

Specification

Are the installed pipe culverts are free of defects like crack

Have the jointing of the pipes done properly and collars satisfactorilygrouted

Has the pipe culvert invert elevation checked as per the drawings

Does the pipe culvert bed slope conform to the drawings

Have the pipes culvert been backfilled according to the Technical

Specification

Have th

eh

eadwalls constructed as per th

e drawings and inconformance to the Technical Specification

Inspection for Different types of Construction

Pipe Culvert Installation


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Has the foundation location been excavated as per the drawings

Have the bed levels of the foundation excavation been checked as per

the drawings

Have the form works and reinforcements of the Footing, Abutment,

Piers, Girders and slab being properly spaced as per the drawings.

Has the proportion of the concrete mix been as per the mix design

proportion

Have cube and/or cylinder samples taken for concrete compressive

strength

Has slump test taken frequently

Has the minimum compressive strength obtained

Has the slump test satisfactory

Has backfilling at the abutment, piers and footings done properly

Has the bearings, and filter media placed properly

Have the pre cast Concrete beam placed properly on the abutments

and piers

Is the Expansion joint as per the drawings

Inspection for Bridges


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Working drawing checked and approved

Latest revision being used

Bar schedules approved

Reinforcing steel material approved

Bar bending and cutting satisfactory

Corrosion treatment of bars, if required,

satisfactory applied

Bar size and spacing correct

Bar lap length and location correct

Bar tied as specified Bar assembly rigid and adequately supported

Cover to bottom bars correct

Cover to side bars correct

Cover to top bars correct

Cover blocks approved including fixing


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Description Yes No Not available

Method statement approved

Batching plant mixers in working order(separate dispenser for admixture, if required,

available)

Stand by batchers in working order

Water , sand, coarse aggregate, cement, admixture approved

Water, sand, coarse aggregate, cement, cement stock sufficient.

Concrete conveying arrangement (including transit mixers) available in working condition

and of sufficient capacity

Formwork approved

Reinforcement approved

Pre stressing sheathing approved

Concreting equipment in working order

Stand by crane, vibrators present

Tremie in working order (for under water work)

Concrete ganging present, including carpenter, steel fixer, mechanics and electrician

Access provided

Safety arrangements adequate

Lighting provided

Communication between various points provided

arrangements for arranging suspension/stoppage of concrete provided

curing arrangements made

laboratory notified

Inspection for Concrete works


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Description Yes No

Are the site, orientation and plan of the buildings approved?

Is the site layout as per the drawings?

Is the foundation material of the buildings acceptable for the superstructure load or need

improvement?

Is the foundation material compactedsatisfactorily?

Are the materials for masonry work like stone, sand and water approved?

Is the stone for masonry work shaped and dressed satisfactorily?

Is the mortar mix proportion as per the standard requirements of UNOPS?

Is the hardcore and masonry works constructed as per the drawings and site condition?

Is the backfill in foundation construction made with approved material?

Is the back fill material compacted to satisfactory level?

Is the reinforcement arrangement of the grade beam, beams and columns (if any) as per the

drawings?

Is the proportion of cement, sand and coarse aggregates for grade beam and column as per the

UNOPS standards?

Is the walls constructed with fiber cement or other approved material?

Are the walls double and filled with insulating materials?

Is the fittings of the buildings are provided as per the drawings, and UNOPS spec?

Is the floor of the buildings as per the requirements of UNOPS spec?

Is the building painted with approved paint?

Is the paint work maintained regularly?

Inspection for Building


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Procedures

Quantity

Location

Time

Representative sampling?

Sampling


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Testing

Standards Common standards are ASTM, BS,AASHTO

Laboratory management Joint Laboratory,Separate Laboratory, External Laboratory

Contractors will manipulate results to their

interest if there is no proper control duringtesting


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The quantity of the sources

Visual uniformity/variability of the sources

Intended use (more critical materials require exhaustivetesting)

Quality of the sources (more tests will be made on marginalsources)

Type of tests (more number of tests will be made for moreimportant requirements)

The minimum number of tests, however, will not be generallybelow three.

Procedures forM

aterials Source Approval


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Problem soils in Construction


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When we build Let us think that we buildforever, Let it not be for the present

delight!!!

Thank You!

Work Shop - Construction Materials Quality Control

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