Training Report on Constuction Megment

8/3/2019 Training Report on Constuction Megment

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JADAGURU DATTATRAY COLLEGE OF TECHNOLOGY

INDORE

INDUSTRIAL TRAINING

AT

DREAM INFRASTRUCTURE

(RAJKOT)

GUIDED BY:- SUBMITTED BY:-

Kishor kalavadiya CHETAN SOLANKI(Training incharge) 0833CE093D05

(CE 7thSEM)


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ACKNOWLEDGEMENT

I am highly obliged and thankful to my

guide Mr. Kishor Kalavadiya (training incharge) forvaluable suggestion, guidance and inspiration time totime.

I am also very grateful to Mr.Rajubhai

Sonigra and Mr.Pareshbhai Dabhi who hasencouraged & issued me to provide all help from company

to complete this training.

I am also thankful to staff of company for

their kind suggestion & co-operation.

Lastly I express sincere thanks to my

colleagues who directly or indirectly helped me incompleting my task.

Date:././ CHETAN SOLANKI0833CE093D05


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DECLEARATION

I CHETAN SOLANKI student of civilengineering , Jagadaguru Dattatray college of

techonology-INDORE. here by declare that thework presented in the training report, entitledIndustrial Training at DREAM

INFRASTRUCTURE is outcome of my own work,it bona-fied, correct to the best of my knowledgeand this work has been carried out taking care of

Engineering Ethics. The work presented does not

infringe any patented work and has not beensubmitted to any University for the award of any

degree or any professional Diploma.


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CONTENT

1. INTRODUCTION

2. SEQUANCE OF STRUCTURE WORK


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SEQUENCEOF STRUCTURE WORK

1)Site Clearance

2)Demarcation of Site

3)Positioning of Central coordinate ie (0,0,0) as per grid plan

4)Surveying and layout

5)Excavation

6)Laying of PCC

7)Bar Binding and placement of foundation steel

8 )Shuttering and Scaffolding

9)Concreting

10)Electrical and Plumbing

11)Deshuttering

12)Brickwork

13)Doors and windows frames along with lintels

14)Wiring for electrical purposes

15)Plastering

16)Flooring and tiling work

17)Painting

18)

Final Completion and handing over the project


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Definition of Damp-proof course

A course of some impermeable material laid in the

foundation walls of building near the ground to preventdampness from rising into the building.


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Background

Rising damp can occur for various reasons - the failure of anexisting damp proof course, bridging due to the raising of

external ground or internal floor levels, or in older

buildings, the complete absence of a damp proof course.

Brick, stone and mortar are porous allowing damp fromthe ground to rise by capillary action, carrying with it groundsalts including chlorides and nitrates. These salts from

the ground can absorb moisture from the atmosphere

leading to wall dampness in conditions of high relativehumidity. Also they can ruin decorations and break downinternal plaster.

Building standards in many countries require most newbuildings to incorporate a DPC/DPM at the time of

construction. This may consist of a thin strip of plastic, acourse of engineering brick or slate, or a layer ofbitumen.

Materials

Materials widely used for damp proofing include

Flexible materials like hot bitumen, plastic sheets,bituminous felts, sheets of lead, copper, etc.

Semi-rigid materials like mastic asphalt

Rigid materials like impervious bricks, stones, slates,cement mortar or cement concrete painted withbitumen, etc.
http://en.wikipedia.org/wiki/Rising_damp_(structural)http://en.wikipedia.org/wiki/Capillary_actionhttp://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Wallhttp://en.wikipedia.org/wiki/Brickhttp://en.wikipedia.org/wiki/Slatehttp://en.wikipedia.org/wiki/Bitumenhttp://en.wikipedia.org/wiki/Mastic_asphalthttp://en.wikipedia.org/wiki/Rising_damp_(structural)http://en.wikipedia.org/wiki/Capillary_actionhttp://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Wallhttp://en.wikipedia.org/wiki/Brickhttp://en.wikipedia.org/wiki/Slatehttp://en.wikipedia.org/wiki/Bitumenhttp://en.wikipedia.org/wiki/Mastic_asphalt


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Stones

Mortar with waterproofing compounds

Coarse sand layers under floors

Continuous plastic sheets under floors

Construction

A DPC is usually a thick plastic strip bedded into the

mortar between two courses of bricks or blocks. It canoften be seen as a thin plastic line in the mortar near

ground level.

A DPM is usually a thick polythene sheet laid under thefloor slab, to allow the slab to dry out and keep outgroundwater. It is often laid on a bed of sand, to preventthe sharp edges of the hardcore damaging it.

To create a continuous barrier, pieces of DPC or DPM are

welded together. In addition, the DPC is welded to theDPM around the outside edges of the ground floor,

completely sealing the inside of the building from thedamp ground under it.

In a cavity wall, there is usually a DPC in both the outerand inner wall. In the outer wall it is normally 150-200mm above ground level (the height of 2-3 brickcourses). This allows rain to form puddles and splash up

off the ground, without saturating the wall above DPC

level. The wall below the DPC may become saturated inrainy weather. The DPC in the inner wall is usually belowfloor level, (under a suspended timber floor structure),or, with a solid concrete floor, it is usually foundimmediately above the floor slab so that it can be linked

to the DPM under the floor slab. This enables installation
http://en.wiktionary.org/wiki/hardcorehttp://en.wiktionary.org/wiki/hardcore


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of skirting boards above floor level without fear of

puncturing it. Alternatively, instead of fitting separateinner and outer DPCs, it is common in commercialhousebuilding to use a one-piece length of rigid plastic,(albeit an angled section), which fits neatly across the

cavity and slots into both walls (a cavity tray). This

method requires the need for weep vents to enablerainwater ingress to drain from the cavities otherwiserising dampness could occur from above the DPC.

Plaster

Lime plaster

Lime plaster is a mixture of calcium hydroxide and sand

(or other inert fillers). Carbon dioxide in the atmosphere

causes the plaster to set by transforming the calciumhydroxide into calcium carbonate (limestone). Whitewash isbased on the same chemistry.

To make lime plaster, limestone (calcium carbonate) isheated to produce quicklime (calcium oxide). Water is then

added to produce slaked lime (calcium hydroxide), which issold as a white powder. Additional water is added to form

a paste prior to use. The paste may be stored in air-tightcontainers. Once exposed to the atmosphere, the calciumhydroxide turns back into limestone, causing the plasterto set.

Lime plaster was a common building material for wallsurfaces in a process known as lath and plaster, whereby a
http://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Whitewashhttp://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Quicklimehttp://en.wikipedia.org/wiki/Slaked_limehttp://en.wikipedia.org/wiki/Lath_and_plasterhttp://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Whitewashhttp://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Quicklimehttp://en.wikipedia.org/wiki/Slaked_limehttp://en.wikipedia.org/wiki/Lath_and_plaster


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series of wooden strips on a studwork frame was covered

with a semi-dry plaster that hardened into a surface. Theplaster used in most lath and plaster construction wasmainly lime plaster, with a cure time of about a month. Tostabilize the lime plaster during curing, small amounts of

Plaster of Paris were incorporated into the mix. Because

Plaster of Paris sets quickly, "retardants" were used toslow setting time enough to allow workers to mix largeworking quantities of lime putty plaster. A modern formof this method uses expanded metal mesh over wood ormetal structures, which allows a great freedom of design

as it is adaptable to both simple and compound curves.Today this building method has been partly replaced with

drywall, also composed mostly of gypsum plaster. In both

these methods a primary advantage of the material isthat it is resistant to a fire within a room and so canassist in reducing or eliminating structural damage or

destruction provided the fire is promptly extinguished.

Lime plaster is used for true frescoes. Pigments, diluted in

water, are applied to the still wet plaster.

Cement plaster

Cement plaster is a mixture of suitable plaster, sand,

portland cement and water which is normally applied to

masonry interiors and exteriors to achieve a smoothsurface. Interior surfaces sometimes receive a final layer

of gypsum plaster. Walls constructed with stock bricks arenormally plastered while face brick walls are not plastered.Various cement-based plasters are also used asproprietary spray fireproofing products. These usually use

vermiculite as lightweight aggregate. Heavy versions ofsuch plasters are also in use for exterior fireproofing, to

protect LPG vessels, pipe bridges and vessel skirts.
http://en.wikipedia.org/wiki/Wall_studhttp://en.wikipedia.org/wiki/Lime_plasterhttp://en.wikipedia.org/wiki/Drywallhttp://en.wikipedia.org/wiki/Frescohttp://en.wikipedia.org/wiki/Pigmenthttp://en.wikipedia.org/wiki/Portland_cementhttp://en.wikipedia.org/wiki/London_stock_brickhttp://en.wikipedia.org/wiki/Brickworkhttp://en.wikipedia.org/wiki/Fireproofinghttp://en.wikipedia.org/wiki/Vermiculitehttp://en.wikipedia.org/wiki/Wall_studhttp://en.wikipedia.org/wiki/Lime_plasterhttp://en.wikipedia.org/wiki/Drywallhttp://en.wikipedia.org/wiki/Frescohttp://en.wikipedia.org/wiki/Pigmenthttp://en.wikipedia.org/wiki/Portland_cementhttp://en.wikipedia.org/wiki/London_stock_brickhttp://en.wikipedia.org/wiki/Brickworkhttp://en.wikipedia.org/wiki/Fireproofinghttp://en.wikipedia.org/wiki/Vermiculite


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Gypsum plaster

Plaster of Paris is a type of building material based on

calcium sulphatehemihydrate, nominally CaSO41/2H2O. It iscreated by heating gypsum to about 300F (150 C).

2 CaSO42H2O 2 CaSO40.5H2O + 3 H2O (released

as steam).

A large gypsum deposit at Montmartre in Paris is the sourceof the name. When the dry plaster powder is mixed withwater, it re-forms into gypsum.

One of the skills used in movie and theatrical sets is thatof "plasterer", gypsum plaster often being used to simulatethe appearance of surfaces of wood, stone, or metal.

Nowadays, plasterers are just as likely to use expandedpolystyrene, although the job title remains unchanged.

TypeStart of

setting inSetting

timeVolumechange

1.A-fastsetting 2 min 15 min +1%

2.B-regularsetting

6min 30min +1%

3.C-slowsetting 20min 90min +2%

Masonry
http://en.wikipedia.org/wiki/Calcium_sulphatehttp://en.wikipedia.org/wiki/Hydratehttp://en.wikipedia.org/wiki/Gypsumhttp://en.wikipedia.org/wiki/Montmartrehttp://en.wikipedia.org/wiki/Parishttp://en.wikipedia.org/wiki/Plastererhttp://en.wikipedia.org/wiki/Polystyrenehttp://en.wikipedia.org/wiki/Calcium_sulphatehttp://en.wikipedia.org/wiki/Hydratehttp://en.wikipedia.org/wiki/Gypsumhttp://en.wikipedia.org/wiki/Montmartrehttp://en.wikipedia.org/wiki/Parishttp://en.wikipedia.org/wiki/Plastererhttp://en.wikipedia.org/wiki/Polystyrene


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Masonry is the building of structures from individual

units laid in and bound together by mortar; the termmasonrycan also refer to the units themselves. Thecommon materials of masonry construction are brick, stonesuch as marble, granite, travertine, limestone; concrete block, glassblock, stucco, and tile. Masonry is generally a highly

durable form of construction. However, the materialsused, the quality of the mortar and workmanship, andthe pattern in which the units are assembled cansignificantly affect the durability of the overall masonryconstruction.

Applications

Masonry is commonly used for the walls of buildings,retaining walls and monuments. Brick and concrete block

are the most common types of masonry in use inindustrialized nations and may be either weight-bearingor a veneer. Concrete blocks, especially those with hollowcores, offer various possibilities in masonry construction.

They generally provide great compressive strength, andare best suited to structures with light transverse loading

when the cores remain unfilled. Filling some or all of thecores with concrete or concrete with steelreinforcement(typically rebar) offers much greater tensileand lateral strength to structures.

Advantages

The use of materials such as brick and stone canincrease the thermal mass of a building, giving

increased comfort in the heat of summer and thecold of winter, and can be ideal for passive solarapplications.
http://en.wikipedia.org/wiki/Mortar_(masonry)http://en.wikipedia.org/wiki/Brickhttp://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Marblehttp://en.wikipedia.org/wiki/Granitehttp://en.wikipedia.org/wiki/Travertinehttp://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Concrete_blockhttp://en.wikipedia.org/wiki/Glasshttp://en.wikipedia.org/wiki/Tilehttp://en.wikipedia.org/wiki/Masonry#Veneer_masonryhttp://en.wikipedia.org/wiki/Rebarhttp://en.wikipedia.org/wiki/Thermal_masshttp://en.wikipedia.org/wiki/Passive_solarhttp://en.wikipedia.org/wiki/Mortar_(masonry)http://en.wikipedia.org/wiki/Brickhttp://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Marblehttp://en.wikipedia.org/wiki/Granitehttp://en.wikipedia.org/wiki/Travertinehttp://en.wikipedia.org/wiki/Limestonehttp://en.wikipedia.org/wiki/Concrete_blockhttp://en.wikipedia.org/wiki/Glasshttp://en.wikipedia.org/wiki/Tilehttp://en.wikipedia.org/wiki/Masonry#Veneer_masonryhttp://en.wikipedia.org/wiki/Rebarhttp://en.wikipedia.org/wiki/Thermal_masshttp://en.wikipedia.org/wiki/Passive_solar


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Brick typically will not require painting and so can

provide a structure with reduced life-cycle costs,although sealing appropriately will reduce potential

spalling due to frost damage. Non-decorative concreteblock generally is painted or stuccoed if exposed.

The appearance, especially when well crafted, can

impart an impression of solidity and permanence. Masonry is very heat resistant and thus provides

good fire protection.

Masonry walls are more resistant to projectiles, suchas debris from hurricanes or tornadoes than walls of wood

or other softer, less dense materials.

Unreinforced Masonry structure built in compression

with (Preferably in lime mortar) has the life of more

than 500 years as compared to 30 to 100 for steel orRCC structure.

Disadvantages

Extreme weather causes degradation of masonrywall surfaces due to frost damage. This type ofdamage is common with certain types of brick,though rare with concrete blocks. If non-concrete

(clay-based) brick is to be used, care should betaken to select bricks suitable for the climate in

question.

Masonry tends to be heavy and must be built upon a

strong foundation (usually reinforced concrete) to avoidsettling and cracking. If expansive soils (such as

adobe clay) are present, this foundation needs to bequite elaborate and the services of a qualified

structural engineer may be required, particularly inearthquake prone regions.
http://en.wikipedia.org/wiki/Spallhttp://en.wikipedia.org/wiki/Frosthttp://en.wikipedia.org/wiki/Stuccohttp://en.wikipedia.org/wiki/Hurricaneshttp://en.wikipedia.org/wiki/Tornadohttp://en.wikipedia.org/wiki/Reinforced_concretehttp://en.wikipedia.org/wiki/Adobe_clayhttp://en.wikipedia.org/wiki/Earthquakehttp://en.wikipedia.org/wiki/Spallhttp://en.wikipedia.org/wiki/Frosthttp://en.wikipedia.org/wiki/Stuccohttp://en.wikipedia.org/wiki/Hurricaneshttp://en.wikipedia.org/wiki/Tornadohttp://en.wikipedia.org/wiki/Reinforced_concretehttp://en.wikipedia.org/wiki/Adobe_clayhttp://en.wikipedia.org/wiki/Earthquake


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Structural limitations

Masonry boasts an impressive compressive strength(vertical loads) but is much lower in tensile strength

(twisting or stretching) unless reinforced. The tensilestrength of masonry walls can be strengthened by

thickening the wall, or by building masonrypiers (verticalcolumns or ribs) at intervals. Where practical, steelreinforcements can be added.

Brick

Solid brickwork is made of two or more layers of bricks with

the units running horizontally (called stretcherbricks)bound together with bricks running transverse to the wall

(called "header" bricks). Each row of bricks is known as acourse. The pattern of headers and stretchers employed

gives rise to different bonds such as the common bond

(with every sixth course composed of headers), theEnglish bond, and the Flemish bond (with alternatingstretcher and header bricks present on every course).

Bonds can differ in strength and in insulating ability.Vertically staggered bonds tend to be somewhat stronger

and less prone to major cracking than a non-staggeredbond.
http://en.wikipedia.org/wiki/Brickworkhttp://en.wikipedia.org/wiki/Transversalityhttp://en.wikipedia.org/wiki/Brickworkhttp://en.wikipedia.org/wiki/Transversality


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Portland cement mortar

Portland cement mortar (often known simply as cement

mortar) is created by mixing Ordinary Portland cement (OPC)with sand and water.

It was invented in 1794 by Joseph Aspdin and patentedon 18 December 1824, largely as a result of variousscientific efforts to develop stronger mortars than existed

at the time. It was popularized during the late nineteenthcentury, and owing to the First World War, by 1930 it had

superseded lime mortar for new construction. The mainreasons for this were that Portland cement sets hard andquickly, allowing a faster pace of construction, andrequires less skilled workers. However, as a general rule,

Portland cement should not be used for the repair ofolder buildings constructed in lime mortar, which require

the flexibility, softness and breathability of lime if theyare to function correctly.
http://en.wikipedia.org/wiki/Portland_cementhttp://en.wikipedia.org/wiki/Sandhttp://en.wikipedia.org/wiki/Portland_cementhttp://en.wikipedia.org/wiki/Sand


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Brickwork bonds

Flemish bond

Flemish bond, also known as Dutch bond, has

historically always been considered the most decorativebond, and for this reason was used extensively for

dwellings until the adoption of the cavity wall. It iscreated by alternately laying headers and stretchers in a

single course. The next course is laid so that a headerlies in the middle of the stretcher in the course below.

This bond is one brick thick. It is quite difficult to layFlemish bond properly, since for best effect all theperpendiculars (vertical mortar joints) need to be verticallyaligned. If only oneface of a Flemish bond wall is

exposed, one third of the bricks are not visible, andhence may be of low visual quality. This is a better ratio

than for English bond, Flemish bond's main rival for load-bearing walls.
http://en.wikipedia.org/wiki/Mortar_(masonry)http://en.wikipedia.org/wiki/File:Billbeee-flemishb.pnghttp://en.wikipedia.org/wiki/Mortar_(masonry)


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A common variation often found in early 18th century

buildings is Glazed-headed Flemish Bond, in which theexposed headers are burned until they vitrify with a blackglassy surface. Monk bond' is a variant of Flemishbond, with two stretchers between the headers in

each row, and the headers centred over the join

between the two stretchers in the row below. Acommon variant isWessex Bondwith three stretchersbetween each header. This is easier to lay than fullFlemish Bond and produces a less intense, butnevertheless "pretty" brickwork face.

English bond

This bond has two alternating courses of stretchers and

headers, with the headers centered on the stretchers,and each alternate row vertically aligned. There is avariant in which the second course of stretchers is half

offset from the first, giving rise to English cross bondor Dutch bond.
http://en.wikipedia.org/wiki/File:Billbeee-eng-bond.PNG


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REINFORCE CEMENT CONCRETE

Use in construction

Concrete is reinforced to give it extra tensile strength;

without reinforcement, many concrete buildings wouldnot have been possible.

Reinforced concrete can encompass many types ofstructures and components, including slabs, walls, beams,

columns, foundations, frames and more.

Reinforced concrete can be classified as precast or cast in-situconcrete.

Much of the focus on reinforcing concrete is placed on floorsystems. Designing and implementing the most efficientfloor system is key to creating optimal buildingstructures. Small changes in the design of a floor systemcan have significant impact on material costs,

construction schedule, ultimate strength, operating costs,occupancy levels and end use of a building.

Behavior of reinforced concrete

Materials

Concrete is a mixture of cement (usually Portland cement)and stone aggregate. When mixed with a small amount ofwater, the cement hydrates form microscopic opaquecrystal lattices encapsulating and locking the aggregateinto a rigid structure. Typical concrete mixes have high

resistance to compressivestresses (about 4,000 psi (28
http://en.wikipedia.org/wiki/Slabhttp://en.wikipedia.org/wiki/Wallhttp://en.wikipedia.org/wiki/Beam_(structure)http://en.wikipedia.org/wiki/Columnhttp://en.wikipedia.org/wiki/Foundation_(architecture)http://en.wikipedia.org/wiki/Framing_(construction)http://en.wikipedia.org/wiki/Precasthttp://en.wikipedia.org/wiki/Cast_in-situ_concretehttp://en.wikipedia.org/wiki/Cast_in-situ_concretehttp://en.wikipedia.org/wiki/Floorhttp://en.wikipedia.org/wiki/Portland_cementhttp://en.wikipedia.org/wiki/Construction_aggregatehttp://en.wikipedia.org/wiki/Hydrateshttp://en.wikipedia.org/wiki/Physical_compressionhttp://en.wikipedia.org/wiki/Stress_(physics)http://en.wikipedia.org/wiki/Slabhttp://en.wikipedia.org/wiki/Wallhttp://en.wikipedia.org/wiki/Beam_(structure)http://en.wikipedia.org/wiki/Columnhttp://en.wikipedia.org/wiki/Foundation_(architecture)http://en.wikipedia.org/wiki/Framing_(construction)http://en.wikipedia.org/wiki/Precasthttp://en.wikipedia.org/wiki/Cast_in-situ_concretehttp://en.wikipedia.org/wiki/Cast_in-situ_concretehttp://en.wikipedia.org/wiki/Floorhttp://en.wikipedia.org/wiki/Portland_cementhttp://en.wikipedia.org/wiki/Construction_aggregatehttp://en.wikipedia.org/wiki/Hydrateshttp://en.wikipedia.org/wiki/Physical_compressionhttp://en.wikipedia.org/wiki/Stress_(physics)


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MPa)); however, any appreciable tension (e.g., due to

bending) will break the microscopic rigid lattice, resulting incracking and separation of the concrete. For this reason,typical non-reinforced concrete must be well supported toprevent the development of tension.

If a material with high strength in tension, such as steel, isplaced in concrete, then the composite material,

reinforced concrete, resists not only compression butalso bending and other direct tensile actions. A reinforcedconcrete section where the concrete resists thecompression and steel resists the tension can be made

into almost any shape and size for the constructionindustry.

Key characteristics

Three physical characteristics give reinforced concrete itsspecial properties.

First, the coefficient of thermal expansion of concrete is similar to

that of steel, eliminating large internal stresses due todifferences in thermal expansion or contraction.

Second, when the cement paste within the concrete

hardens this conforms to the surface details of the steel,permitting any stress to be transmitted efficientlybetween the different materials. Usually steel bars areroughened or corrugated to further improve the bond or

cohesion between the concrete and steel.Third, the alkaline chemical environment provided by the

alkali reserve (KOH, NaOH) and the portlandite (calciumhydroxide) contained in the hardened cement paste causesa passivating film to form on the surface of the steel,making it much more resistant to corrosion than it would be
http://en.wikipedia.org/wiki/Tension_(mechanics)http://en.wikipedia.org/wiki/Bendinghttp://en.wikipedia.org/wiki/Steelhttp://en.wikipedia.org/wiki/Coefficient_of_thermal_expansionhttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Chemical_bondhttp://en.wikipedia.org/wiki/PHhttp://en.wikipedia.org/wiki/Alkalihttp://en.wikipedia.org/wiki/Portlanditehttp://en.wikipedia.org/wiki/Calcium_hydroxidehttp://en.wikipedia.org/wiki/Calcium_hydroxidehttp://en.wikipedia.org/wiki/Passivationhttp://en.wikipedia.org/wiki/Corrosionhttp://en.wikipedia.org/wiki/Tension_(mechanics)http://en.wikipedia.org/wiki/Bendinghttp://en.wikipedia.org/wiki/Steelhttp://en.wikipedia.org/wiki/Coefficient_of_thermal_expansionhttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Chemical_bondhttp://en.wikipedia.org/wiki/PHhttp://en.wikipedia.org/wiki/Alkalihttp://en.wikipedia.org/wiki/Portlanditehttp://en.wikipedia.org/wiki/Calcium_hydroxidehttp://en.wikipedia.org/wiki/Calcium_hydroxidehttp://en.wikipedia.org/wiki/Passivationhttp://en.wikipedia.org/wiki/Corrosion


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in neutral or acidic conditions. When the cement paste

exposed to the air and meteoric water reacts with theatmospheric CO2, portlandite and the Calcium Silicate Hydrate(CSH) of the hardened cement paste becomeprogressively carbonated and the high pH gradually

decreases from 13.5 12.5 to 8.5, the pH of water in

equilibrium with calcite (calcium carbonate) and the steel is nolonger passivated.

As a rule of thumb, only to give an idea on orders ofmagnitude, steel is protected at pH above ~11 but startsto corrode below ~10 depending on

steel characteristics and local physico-chemical conditionswhen concrete becomes carbonated. Carbonation ofconcrete along with chloride ingress are amongst the chief

reasons for the failure ofreinforcement bars in concrete.

The relative cross-sectional area of steel required fortypical reinforced concrete is usually quite small andvaries from 1% for most beams and slabs to 6% for

some columns. Reinforcing bars are normally round in cross-section and vary in diameter. Reinforced concrete

structures sometimes have provisions such as ventilatedhollow cores to control their moisture & humidity.

Distribution of concrete (in spite of reinforcement)strength characteristics along the cross-section of verticalreinforced concrete elements is inhomogeneous.

CONSTRUCTION PROCESS AND MATERIALS USED

Site Clearance- The very first step is site clearance which involves removal

of grass and vegetation along with any other objections which might bethere in the site location.
http://en.wikipedia.org/wiki/Calcium_Silicate_Hydratehttp://en.wikipedia.org/wiki/CSHhttp://en.wikipedia.org/wiki/Calcitehttp://en.wikipedia.org/wiki/Calcium_carbonatehttp://en.wikipedia.org/wiki/Carbonationhttp://en.wikipedia.org/wiki/Chloridehttp://en.wikipedia.org/wiki/Reinforcement_barhttp://en.wikipedia.org/wiki/Areahttp://en.wikipedia.org/wiki/Rebarhttp://en.wikipedia.org/wiki/Calcium_Silicate_Hydratehttp://en.wikipedia.org/wiki/CSHhttp://en.wikipedia.org/wiki/Calcitehttp://en.wikipedia.org/wiki/Calcium_carbonatehttp://en.wikipedia.org/wiki/Carbonationhttp://en.wikipedia.org/wiki/Chloridehttp://en.wikipedia.org/wiki/Reinforcement_barhttp://en.wikipedia.org/wiki/Areahttp://en.wikipedia.org/wiki/Rebar


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Demarcation of Site- The whole area on which construction is to be done is

marked so as to identify the construction zone. In our project, a plot of450*350 sq ft was chosen and the respective marking was done.

Positioning of Central coordinate and layout- The centre point was

marked with the help of a thread and plumb bob as per the grid drawing.With respect to this center point, all the other points of columns were to be

decided so its exact position is very critical.

Excavation

Excavation was carried out both manually as well as mechanically. Normally

1-2 earth excavators (JCBs) were used for excavating the soil. Adequateprecautions are taken to see that the excavation operations do not damage

the adjoining structures. Excavation is carried out providing adequate side

slopes and dressing of excavation bottom. The soil present beneath thesurface was too clayey so it was dumped and was not used for back filling.

The filling is done in layer not exceeding 20 cm layer and than itscompacted. Depth of excavation was 54 from Ground Level.

PCC Plain Cement Concrete

After the process of excavation, laying of plain cement concrete that is PCC

is done. A layer of 4 inches was made in such a manner that it was notmixed with the soil. It provides a solid bas for the raft foundation and a mix

of 1:5:10 that is, 1 part of cement to 5 parts of fine aggregates and 10 parts

of coarse aggregates by volume were used in it. Plain concrete is vibrated toachieve full compaction. Concrete placed below ground should be protected

from falling earth during and after placing. Concrete placed in groundcontaining deleterious substances should be kept free from contact with such

a ground and with water draining there from during placing and for a periodof seven days. When joint in a layer of concrete are unavoidable, and end is

sloped at an angle of 30 and junctions of different layers break joint in layingupper layer of concrete. The lower surface is made rough and clean watered

before upper layer is laid.


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LAYINGOF FOUNDATION

At our site, Raft foundations are used to spread the load from a structure

over a large area, normally the entire area of the structure. Normally raftfoundation is used when large load is to be distributed and it is not possible

to provide individual footings due to space constraints that is they wouldoverlap on each other. Raft foundations have the advantage of reducing

differential settlements as the concrete slab resists differential movementsbetween loading positions. They are often needed on soft or loose soils with

low bearing capacity as they can spread the loads over a larger area.

In laying of raft foundation, special care is taken in the reinforcement andconstruction of plinth beams and columns. It is the main portion on which

ultimately whole of the structure load is to come. So a slightest error can

cause huge problems and therefore all this is checked and passed by theengineer in charge of the site.


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Apart from raft foundation, individual footings were used in the mess areawhich was extended beyond the C and D blocks.


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CEMENT

Portland cement is composed of calcium silicates and aluminate and

aluminoferrite It is obtained by blending predetermined proportionslimestone clay and other minerals in small quantities which is pulverized and

heated at high temperature around 1500 deg centigrade to produce clinker. The clinker is then ground with small quantities of gypsum to

produce a fine powder called Ordinary Portland Cement (OPC). When mixedwith water, sand and stone, it combines slowly with the water to form a hard

mass called concrete. Cement is a hygroscopic material meaning that it

absorbs moisture In presence of moisture it undergoes chemical reactiontermed as hydration. Therefore cement remains in good condition as long as

it does not come in contact with moisture. If cement is more than threemonths old then it should be tested for its strength before being taken into

use.

The Bureau of Indian Standards (BIS) has classified OPC in three differentgrades The classification is mainly based on the compressive strength of

cement-sand mortar cubes of face area 50 cm2 composed of 1 part of

cement to 3 parts of standard sand by weight with a water-cement ratioarrived at by a specified procedure. The grades are

(i) 33 grade

(ii) 43 grade

(iii) 53 grade

The grade number indicates the minimum compressive strength of cement

sand mortar in N/mm2 at 28 days, as tested by above mentioned procedure.

Portland Pozzolana Cement (PPC) is obtained by either intergrinding apozzolanic material with clinker and gypsum, or by blending ground

pozzolana with Portland cement. Nowadays good quality fly ash is availablefrom Thermal Power Plants, which are processed and used in manufacturing

of PPC.

ADVANTAGESOFUSING PORTLANDPOZZOLANACEMENTOVEROPC

Pozzolana combines with lime and alkali in cement when water is added and

forms compounds which contribute to strength, impermeability and sulphateresistance. It also contributes to workability, reduced bleeding and controls

destructive expansion from alkali-aggregate reaction. It reduces heat of


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hydration thereby controlling temperature differentials, which causes

thermal strain and resultant cracking n mass concrete structures like dams.The colour of PPC comes from the colour of the pozzolanic material used.

PPC containing fly ash as a pozzolana will invariably be slightly differentcolour than the OPC.One thing should be kept in mind that is the quality of

cement depends upon the raw materials used and the quality control

measures adopted during its manufacture, and not on the shade of thecement. The cement gets its colour from the nature and colour of raw

materials used, which will be different from factory to factory, and may evendiffer in the different batches of cement produced in a factory. Further, the

colour of the finished concrete is affected also by the colour of the

aggregates, and to a lesser extent by the colour of the cement. Preferencefor any cement on the basis of colour alone is technically misplaced.

SETTLING OF CEMENT

When water is mixed with cement, the paste so formed remains pliable and

plastic for a short time. During this period it is possible to disturb the pasteand remit it without any deleterious effects. As the reaction between waterand cement continues, the paste loses its plasticity. This early period in the

hardening of cement is referred to as setting of cement.

INITIALANDFINALSETTINGTIMEOFCEMENT

Initial set is when the cement paste loses its plasticity and stiffens

considerably. Final set is the point when the paste hardens and can sustain

some minor load. Both are arbitrary points and these are determined by

Vicat needle penetration resistance

Slow or fast setting normally depends on the nature of cement. It could also

be due to extraneous factors not related to the cement. The ambientconditions play an important role. In hot weather, the setting is faster, in

cold weather, setting is delayed Some types of salts, chemicals, clay, etc ifinadvertently get mixed with the sand, aggregate and water could accelerate

or delay the setting of concrete.

STORAGEOF CEMENT


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It needs extra care or else can lead to loss not only in terms of financial loss

but also in terms of loss in the quality. Following are the dont that should befollowed -

(i) Do not store bags in a building or a godown in which the walls, roof and

floor are not completely weatherproof.

(ii) Do not store bags in a new warehouse until the interior has thoroughly

dried out.

(iii) Do not be content with badly fitting windows and doors, make sure theyfit properly and ensure that they are kept shut.

(iv) Do not stack bags against the wall. Similarly, dont pile them on the

floor unless it is a dry concrete floor. If not, bags should be stacked onwooden planks or sleepers.

(v) Do not forget to pile the bags close together

(vi) Do not pile more than 15 bags high and arrange the bags in a header-and-stretcher fashion.

(vii) Do not disturb the stored cement until it is to be taken out for use.

(viii) Do not take out bags from one tier only. Step back two or three tiers.


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(ix) Do not keep dead storage. The principle of first-in first-out should be

followed in removing bags.

(x) Do not stack bags on the ground for temporary storage at work site. Pile

them on a raised, dry platform and cover with tarpaulin or polythene sheet.

Damp-proof course

A course of some impermeable material laid in the foundation walls ofbuilding near the ground to prevent dampness from rising into the building.

Rising damp can occur for various reasons - the failure of an existing damp

proof course, bridging due to the raising of external ground or internal floorlevels, or in older buildings, the complete absence of a damp proof course.

Brick, stone and mortar are porous allowing damp from the ground to rise by

capillary action, carrying with it ground salts including chlorides and nitrates.These salts from the ground can absorb moisture from the atmosphere

leading to wall dampness in conditions of high relative humidity. Also theycan ruin decorations and break down internal plaster.

Building standards in many countries require most new buildings to

incorporate a DPC/DPM at the time of construction. This may consist of athin strip of plastic, a course of engineering brick or slate, or a layer of

bitumen.

Materials

Materials widely used for damp proofing include

Flexible materials like hot bitumen, plastic sheets, bituminous felts,sheets of lead, copper, etc.

Semi-rigid materials like mastic asphalt

Rigid materials like impervious bricks, stones, slates, cement mortar or

cement concrete painted with bitumen, etc.

Stones

Mortar with waterproofing compounds

Coarse sand layers under floors Continuous plastic sheets under floors

Construction
http://en.wikipedia.org/wiki/Rising_damp_(structural)http://en.wikipedia.org/wiki/Capillary_actionhttp://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Wallhttp://en.wikipedia.org/wiki/Brickhttp://en.wikipedia.org/wiki/Slatehttp://en.wikipedia.org/wiki/Bitumenhttp://en.wikipedia.org/wiki/Mastic_asphalthttp://en.wikipedia.org/wiki/Rising_damp_(structural)http://en.wikipedia.org/wiki/Capillary_actionhttp://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Wallhttp://en.wikipedia.org/wiki/Brickhttp://en.wikipedia.org/wiki/Slatehttp://en.wikipedia.org/wiki/Bitumenhttp://en.wikipedia.org/wiki/Mastic_asphalt


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A DPC is usually a thick plastic strip bedded into the mortar between two

courses of bricks or blocks. It can often be seen as a thin plastic line in themortar near ground level.

A DPM is usually a thick polythene sheet laid under the floor slab, to allow

the slab to dry out and keep out groundwater. It is often laid on a bed ofsand, to prevent the sharp edges of the hardcore damaging it.

To create a continuous barrier, pieces of DPC or DPM are welded together. Inaddition, the DPC is welded to the DPM around the outside edges of theground floor, completely sealing the inside of the building from the damp

ground under it.

In a cavity wall, there is usually a DPC in both the outer and inner wall. In

the outer wall it is normally 150-200mm above ground level (the height of

2-3 brick courses). This allows rain to form puddles and splash up off theground, without saturating the wall above DPC level. The wall below the DPC

may become saturated in rainy weather. The DPC in the inner wall is usuallybelow floor level, (under a suspended timber floor structure), or, with a solid

concrete floor, it is usually found immediately above the floor slab so that itcan be linked to the DPM under the floor slab. This enables installation ofskirting boards above floor level without fear of puncturing it. Alternatively,

instead of fitting separate inner and outer DPCs, it is common in commercialhousebuilding to use a one-piece length of rigid plastic, (albeit an angled

section), which fits neatly across the cavity and slots into both walls (a

cavity tray). This method requires the need for weep vents to enablerainwater ingress to drain from the cavities otherwise rising dampness could

occur from above the DPC.

COARSE AGGREGATE

Coarse aggregate for the works should be river gravel or crushed stone .It

should be hard, strong, dense, durable, clean, and free from clay or loamyadmixtures or quarry refuse or vegetable

matter. The pieces of aggregates should be cubical, or rounded shaped and

should have granular or crystalline or smooth (but not glossy) non-powderysurfaces.Aggregates should be properly screened and if necessary washedclean before use.

Coarse aggregates containing flat, elongated or flaky pieces or mica should

be rejected. The grading of coarse aggregates should be as perspecifications of IS-383.
http://en.wiktionary.org/wiki/hardcorehttp://en.wiktionary.org/wiki/hardcore


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After 24-hrs immersion in water, a previously dried sample of the coarse aggregate

should not gain in weight more than 5%.

Aggregates should be stored in such a way as to prevent segregation ofsizes and avoid contamination with fines.

Depending upon the coarse aggregate color, there quality can be determined as:

Black => very good quality

Blue => good

Whitish =>bad quality

FINE AGGREGATE

Aggregate which is passed through 4.75 IS Sieve is termed as fine

aggregate. Fine aggregate is added to concrete to assist workability and tobring uniformity in mixture. Usually, the natural river sand is used as fine

aggregate. Important thing to be considered is that fine aggregates shouldbe free from coagulated lumps.

Grading of natural sand or crushed stone i.e. fine aggregates shall be such

that not more than 5 percent shall exceed 5 mm in size, not more than 10%shall IS sieve No. 150 not less than 45% or more than 85% shall pass IS

sieve No. 1.18 mm and not less than 25% or more than 60% shall pass ISsieve No. 600 micron.

BRICKWORK

Brickwork is masonry done with bricks and mortar and is generally used to

build partition walls. In our site, all the external walls were of concrete andmost of the internal walls were made of bricks. English bond was used and a

ration of 1:4 (1 cement: 4 coarse sand) and 1:6 were used depending uponwhether the wall is 4.5 inches or 9 inches. The reinforcement shall be 2 nos.

M.S. round bars or as indicated. The diameter of bars was 8mm. The firstlayer of reinforcement was used at second course and then at every fourth

course of brick work. The bars were properly anchored at their ends where

the portions and or where these walls join with other walls. The in laid steelreinforcement was completely embedded in mortar.

Bricks can be of two types. These are:


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1) Traditional Bricks-The dimension if traditional bricks vary from 21 cm to

25cm in length,10 to 13 cm in width and 7.5 cm in height in different partsof country .The commonly adopted normal size of traditional brick is 23 *

11.5*7.5 cm with a view to achieve uniformity in size of bricks all overcountry.

2) Modular Bricks- Indian standard institution has established a standard

size of bricks such a brick is known as a modular brick. The normal size of

brick is taken as 20*10*10 cm whereas its actual dimensions are 19*9*9 cmmasonry with modular bricks workout to be cheaper there is saving in the

consumption of bricks, mortar and labour as compared with masonry withtraditional bricks.

STRENGTHOFBRICKMASONRY

The permissible compressive stress in brick masonry depends upon thefollowing factors:

1. Type and strength of brick.

2. Mix of motor.

3. Size and shape of masonry construction.

The strength of brick masonry depends upon the strength of bricks used in

the masonry construction. The strength of bricks depends upon the nature ofsoil used for making and the method adopted for molding and burning of

bricks .since the nature of soil varies from region to region ,the average

strength of bricks varies from as low as 30kg/sq cm to 150 kg /sq cm the

basic compressive stress are different crushing strength.


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There are many checks that can be applied to see the quality of bricks usedon the site.Normally the bricks are tested for Compressive strength, water

absorption, dimensional tolerances and efflorescence. However at small

construction sites the quality of bricks can be assessed based on following,which is prevalent in many sites.

Visual check Bricks should be well burnt and of uniform size and color.

Striking of two bricks together should produce a metallic ringing sound.

It should have surface so hard that cant be scratched by the fingernails.

A good brick should not break if dropped in standing position from one

metre above ground level.

A good brick shouldnt absorb moisture of more than 15-20% by weight,when soaked in water For example; a good brick of 2 kg shouldnt

weigh more than 2.3 to 2.4 kg if immersed in water for 24 hours.

PRECAUTIONS

TO

BE

TAKEN

IN

BRICK

MASONRY

WORK

Bricks should be soaked in water for adequate period so that the water

penetrates

to its full thickness. Normally 6 to 8 hours of wetting is sufficient.

A systematic bond must be maintained throughout the brickwork. Vertical

joints


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shouldnt be continuous but staggered.

The joint thickness shouldnt exceed 1 cm. It should be thoroughly filledwith the

cement mortar 1:4 to 1:6 (Cement: Sand by volume)

All bricks should be placed on their bed with frogs on top (depression on

top of the

brick for providing bond with mortar).

Thread, plumb bob and spirit level should be used for alignment, verticality

and

horizontality of construction.

Joints should be raked and properly finished with trowel or float, to provide

good bond.

A maximum of one metre wall height should be constructed in a day.

Brickwork should be properly cured for at least 10 days

REINFORCEMENT

Steel reinforcements are used, generally, in the form of bars of circular crosssection in concrete structure. They are like a skeleton in human body. Plain

concrete without steel or any other reinforcement is strong in compressionbut weak in tension. Steel is one of the best forms of reinforcements, to take

care of those stresses and to strengthen concrete to bear all kinds of loads

Mild steel bars conforming to IS: 432 (Part I) and Cold-worked steel highstrength deformed bars conforming to IS: 1786 (grade Fe 415 and grade Fe

500, where 415 and 500 indicate yield stresses 415 N/mm2 and 500 N/mm2

respectively) are commonly used. Grade Fe 415 is being used mostcommonly nowadays. This has limited the use of plain mild steel bars

because of higher yield stress and bond strength resulting in saving of steel

quantity. Some companies have brought thermo mechanically treated (TMT)and corrosion resistant steel (CRS) bars with added features.

Bars range in diameter from 6 to 50 mm. Cold-worked steel high strengthdeformed bars start from 8 mm diameter. For general house constructions,

bars of diameter 6 to 20 mm are used


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Transverse reinforcements are very important. They not only take care of

structural requirements but also help main reinforcements to remain indesired position. They play a very significant role while abrupt changes or

reversal of stresses like earthquake etc.

They should be closely spaced as per the drawing and properly tied to themain/longitudinal reinforcement

TERMSUSEDIN REINFORCEMENT

BAR-BENDING-SCHEDULE

Bar-bending-schedule is the schedule of reinforcement bars prepared in

advance before cutting and bending of rebars. This schedule contains alldetails of size, shape and dimension of rebars to be cut.

LAPLENGTH

Lap length is the length overlap of bars tied to extend the reinforcementlength.. Lap length about 50 times the diameter of the bar is considered

safe. Laps of neighboring bar lengths should be staggered and should not be

provided at one level/line. At one cross section, a maximum of 50% barsshould be lapped. In case, required lap length is not available at junction

because of space and other constraints, bars can be joined with couplers orwelded (with correct choice of method of welding).

ANCHORAGE LENGTH

This is the additional length of steel of one structure required to be inserted

in other at the junction. For example, main bars of beam in column at beamcolumn junction, column bars in

footing etc. The length requirement is similar to the lap length mentioned in

previous question or as per the design instructions

COVERBLOCK

Cover blocks are placed to prevent the steel rods from touching the

shuttering plates and there by providing a minimum cover and fix thereinforcements as per the design drawings. Sometimes it is commonly seen

that the cover gets misplaced during the concreting activity. To prevent this,

tying of cover with steel bars using thin steel wires called binding wires(projected from cover surface and placed during making or casting of cover

blocks) is recommended. Covers should be made of cement sand mortar


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(1:3). Ideally, cover should have strength similar to the surrounding

concrete, with the least perimeter so that chances of water to penetratethrough periphery will be minimized. Provision of minimum covers as per the

Indian standards for durability of the whole structure should be ensured.

Shape of the cover blocks could be cubical or cylindrical. However, coverindicates thickness of the cover block. Normally, cubical cover blocks are

used. As a thumb rule, minimum cover of 2 in footings, 1.5 in columns and

1 for other structures may be ensured.

Structural element Cover to reinforcement (mm)

Footings 40

Columns 40

Slabs 15

Beams 25

Retaining wall 25 for earth face

20 for other face

THINGSTO NOTE

Reinforcement should be free from loose rust, oil paints, mud etc. it should

be cut, bent and fixed properly. The reinforcement shall be placed andmaintained in position by providing proper cover blocks, spacers, supporting

bars, laps etc. Reinforcements shall be placed and tied such that concreteplacement is possible without segregation, and compaction possible by an

immersion vibrator.

For any steel reinforcement bar, weight per running meter is equal to

d*d/162 Kg, where d is diameter of the bar in mm. For example, 10 mmdiameter bar will weigh 1010/162 = 0.617 Kg/m

Three types of bars were used in reinforcement of a slab. These includestraight bars, crank bar and an extra bar. The main steel is placed in which

the straight steel is binded first, then the crank steel is placed and extrasteel is placed in the end. The extra steel comes over the support while

crank is encountered at distance of (1-distance between the supports)

from the surroundings supports.

For providing nominal cover to the steel in beam, cover blocks were usedwhich were made of concrete and were casted with a thin steel wire in the

center which projects outward. These keep the reinforcement at a distance


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from bottom of shuttering. For maintaining the gap between the main steel

and the distribution steel, steel chairs are placed between them

SHUTTERING AND SCAFFOLDING

DEFINITION

The term SHUTTERING or FORMWORK includes all forms, moulds,

sheeting, shuttering planks, walrus, poles, posts, standards, leizers, V-Heads, struts, and structure, ties, prights, walling steel rods, bolts, wedges,

and all other temporary supports to the concrete during the process ofsheeting.

FORM WORK

Forms or moulds or shutters are the receptacles in which concrete is placed,so that it will have the desired shape or outline when hardened. Once the

concrete develops adequate strength, the forms are removed. Forms are

generally made of the materials like timber, plywood, steel, etc.

Generally camber is provided in the formwork for horizontal members to

counteract the effect of deflection caused due to the weight of reinforcement

and concrete placed over that. A proper lubrication of shuttering plates isalso done before the placement of reinforcement. The oil film


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sandwiched between concrete and formwork surface not only helps in easy

removal of shuttering but also prevents loss of moisture from the concretethrough absorption and evaporation.

The steel form work was designed and constructed to the shapes, lines and

dimensions shown on the drawings. All forms were sufficiently water tight toprevent leakage of mortar. Forms were so constructed as to be removable in

sections. One side of the column forms were left open and the open side

filled in board by board successively as the concrete is placed andcompacted except when vibrators are used. A key was made at the end of

each casting in concrete columns of appropriate size to give proper bondingsto columns and walls as per relevant IS.

CLEANING AND TREATMENT OF FORMS

All rubbish, particularly chippings, shavings and saw dust, was removed

from the interior of the forms (steel) before the concrete is placed. The formwork in contact with the concrete was cleaned and thoroughly wetted or

treated with an approved composition to prevent adhesion between form

work and concrete. Care was taken that such approved composition is kept

out of contact with the reinforcement.

DESIGN

The form-work should be designed and constructed such that the concretecan be properly placed and thoroughly compacted to obtain the required

shape, position, and levels subject


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ERECTION OF FORMWORK

The following applies to all formwork:

a) Care should be taken that all formwork is set to plumb and true to lineand level.

b) When reinforcement passes through the formwork care should be taken

to ensure close

fitting joints against the steel bars so as to avoid loss of fines during thecompaction of

concrete.

c) If formwork is held together by bolts or wires, these should be so fixedthat no iron is

exposed on surface against which concrete is to be laid.

d) Provision is made in the shuttering for beams, columns and walls for a

port hole of

convenient size so that all extraneous materials that may be collected could

be

removed just prior to concreting.

e) Formwork is so arranged as to permit removal of forms without jarring

the concrete.

Wedges, clamps, and bolts should be used where practicable instead of nails.

f) Surfaces of forms in contact with concrete are oiled with a mould oil ofapproved

quality. The use of oil, which darkens the surface of the concrete, is notallowed. Oiling

is done before reinforcement is placed and care taken that no oil comes in

contact with

the reinforcement while it is placed in position. The formwork is keptthoroughly wet


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during concreting and the whole time that it is left in place.

Immediately before concreting is commenced, the formwork iscarefully examined to ensure the following:

a) Removal of all dirt, shavings, sawdust and other refuse by brushing and

washing.

b) The tightness of joint between panels of sheathing and between theseand any hardened core.

c) The correct location of tie bars bracing and spacers, and especiallyconnections of

bracing.

d) That all wedges are secured and firm in position.

e) That provision is made for traffic on formwork not to bear directly on

reinforcement

steel.

VERTICALITY OF THE STUCTURE

All the outer columns of the frame were checked for plumb by plumb-bob as

the work proceeds to upper floors. Internal columns were checked by taking

measurements from outer row of columns for their exact position. Jack wereused to lift the supporting rods called props

STRIPPING TIME OR REMOVAL OF FORMWORK

Forms were not struck until the concrete has attained a strength at leasttwice the stress to which the concrete may be subjected at the time of

removal of form work. The strength referred is that of concrete using the

same cement and aggregates with the same proportions and cured underconditions of temperature and moisture similar to those existing on the

work. Where so required, form work was left longer in normal circumstances

Form work was removed in such a manner as would not cause any shock or

vibration that would damage the concrete. Before removal of props, concrete

surface was exposed to ascertain that the concrete has sufficientlyhardened. Where the shape of element is such that form work has re-entrant

angles, the form work was removed as soon as possible after the concretehas set, to avoid shrinkage cracking occurring due to the restraint imposed.


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As a guideline, with temperature above 20 degree following time limits

should be followed:

Structural Component Age

Footings 1 day

Sides of beams, columns, lintels, wall 2 days

Underside of beams spanning less than 6m 14 days

Underside of beams spanning over 6m 21 days

Underside of slabs spanning less than 4m 7 days

Underside of slabs spanning more than 4m 14 days

Flat slab bottom 21 days

CEMENT:

Portland cement is composed of calcium silicates and aluminate

and aluminoferrite It is obtained by blending predetermined

proportions limestone clay and other minerals in small quantities

which is pulverized and heated at high temperature around

1500 deg centigrade to produce clinker. The clinker is then

ground with small quantities of gypsum to produce a fine powdercalled Ordinary Portland Cement (OPC). When mixed with water,

sand and stone, it combines slowly with the water to form a hard

mass called concrete. Cement is a hygroscopic material meaning

that it absorbs moisture In presence of moisture it undergoes

chemical reaction termed as hydration. Therefore cement remains

in good condition as long as it does not come in contact withmoisture. If cement is more than three months old then it should

be tested for its strength before being taken into use.


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The Bureau of Indian Standards (BIS) has classified OPC in three

different grades The classification is mainly based on the

compressive strength of cement-sand mortar cubes of face area

50 cm2 composed of 1 part of cement to 3 parts of standard sand

by weight with a water-cement ratio arrived at by a specified

procedure. The grades are

(i) 33 grade

(ii) 43 grade

(iii) 53 grade

The grade number indicates the minimum compressive strength

of cement sand mortar in N/mm2 at 28 days, as tested by above

mentioned procedure.

Portland Pozzolana Cement (PPC) is obtained by either

intergrinding a pozzolanic material with clinker and gypsum, or by

blending ground pozzolana with Portland cement. Nowadays good

quality fly ash is available from Thermal Power Plants, which are

processed and used in manufacturing of PPC.

ADVANTAGESOFUSING PORTLANDPOZZOLANACEMENTOVEROPC:

Pozzolana combines with lime and alkali in cement when water is

added and forms compounds which contribute to strength,

impermeability and sulphate resistance. It also contributes to


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workability, reduced bleeding and controls destructive expansion

from alkali-aggregate reaction. It reduces heat of hydration

thereby controlling temperature differentials, which causes

thermal strain and resultant cracking n mass concrete structures

like dams. The colour of PPC comes from the colour of the

pozzolanic material used. PPC containing fly ash as a pozzolana

will invariably be slightly different colour than the OPC.One thing

should be kept in mind that is the quality of cement depends

upon the raw materials used and the quality control measures

adopted during its manufacture, and not on the shade of the

cement. The cement gets its colour from the nature and colour of

raw materials used, which will be different from factory to

factory, and may even differ in the different batches of cement

produced in a factory. Further, the colour of the finished concrete

is affected also by the colour of the aggregates, and to a lesser

extent by the colour of the cement. Preference for any cement on

the basis of colour alone is technically misplaced.

SETTLING OF CEMENT :

When water is mixed with cement, the paste so formed remains

pliable and plastic for a short time. During this period it ispossible to disturb the paste and remit it without any deleterious

effects. As the reaction between water and cement continues, the

paste loses its plasticity. This early period in the hardening of

cement is referred to as setting of cement.


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INITIALANDFINALSETTINGTIMEOFCEMENT:

Initial set is when the cement paste loses its plasticity and

stiffens considerably. Final set is the point when the paste

hardens and can sustain some minor load. Both are arbitrary

points and these are determined by Vicat needle penetration

resistance.

Slow or fast setting normally depends on the nature of cement. It

could also be due to extraneous factors not related to the

cement. The ambient conditions play an important role. In hot

weather, the setting is faster, in cold weather, setting is delayed

Some types of salts, chemicals, clay, etc if inadvertently get

mixed with the sand, aggregate and water could accelerate or

delay the setting of concrete.

LIST OF TOOLS & EQUIPMENT

1) Shovel2) Pan M.S. 35 cms diameter 128

3) Forma wooden for measuring aggregate4) Bucket C.I. 35 cms diameter5) Masons Plumb Rule with Spirit level

6) Masons Square 30 cms x 30 cms7) Sieve for Sand 1/16 inches, 100 x 60 cms.8) Sieve for Sand 1/8 inches, 100 x 60 cms.

9) Trowel 10 x 3 10) Tool Cutting Set of 611) Brick Hammer with Handle


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12) Rule 4 folds wooden 60 cms.

13) 6 Painting Trowel14) Line Pins Corner Block15) Motor Board16) Wire Board

17) Wooden Float

18) Steel Float19) Spirit Level 1220) Chisel hammer headed21) Bolster22) Claw Hammer

23) Spade24) Measuring tape 100 (Steel)

25) Ladder aluminium 10 feet height

26) Pick Axe27) Rammer Axe28) Crow bar 1 diameter 5 feet long

29)Hand Hammer 2 lbs.

Training Report on Constuction Megment

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