construction Project Report

7/21/2019 construction Project Report

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Project Report – Six Months Summer Training

Here is the project report of a civil engineering student who has spent 6 months on a training

site.Due to security reasons,the project details, estimation, some portion of design and quantity

calculations have been omitted.But to help the civil engineering students we had shown all thenecessary works..

SEQUENCE OF STRUCTURE WOR

!" Site C#earance

$" %emarcation o& Site

'" Positioning o& Centra# coor(inate ie )*+ *+ *" as per gri( p#an

," Sur-e.ing an( #a.out

/" Exca-ation

0" 1a.ing o& PCC

2" 3ar 3in(ing an( p#acement o& &oun(ation stee#

4 " Shuttering an( Sca&&o#(ing

5" Concreting

!*" E#ectrica# an( P#um6ing

!!" %eshuttering

!$" 3ric78or7

!'" %oors an( 8in(o8s &rames a#ong 8ith #inte#s

!," Wiring &or e#ectrica# purposes

!/" P#astering

!0" F#ooring an( ti#ing 8or7

!2" Painting

!4" Fina# Comp#etion an( han(ing o-er the project

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CONSTRUCT9ON PROCESS :N% M:TER9:1S USE%

Site C#earance !he very first step is site clearance which involves removal of grass and

vegetation along with any other objections which might be there in the site location.

%emarcation o& Site !he whole area on which construction is to be done is marked so as toidentify the construction "one. #n our project, a plot of $%&'(%& sq ft was chosen and the

respective marking was done.

Positioning o& Centra# coor(inate an( #a.out !he centre point was marked with the help of athread and plumb bob as per the grid drawing. )ith respect to this center point, all the other

points of columns were to be decided so its e*act position is very critical.

Exca-ation

+*cavation was carried out both manually as well as mechanically. ormally - earth

e*cavators /01B2s3 were used for e*cavating the soil. 4dequate precautions are taken to see thatthe e*cavation operations do not damage the adjoining structures. +*cavation is carried out

providing adequate side slopes and dressing of e*cavation bottom. !he soil present beneath the

surface was too clayey so it was dumped and was not used for back filling. !he filling is done inlayer not e*ceeding & cm layer and than its compacted. Depth of e*cavation was %2$5 from

round 7evel.

PCC – P#ain Cement Concrete



4fter the process of e*cavation, laying of plain cement concrete that is 811 is done. 4 layer of $

inches was made in such a manner that it was not mi*ed with the soil. #t provides a solid bas for

the raft foundation and a mi* of -9%9-& that is, - part of cement to % parts of fine aggregates and-& parts of coarse aggregates by volume were used in it. 8lain concrete is vibrated to achieve full

compaction. 1oncrete placed below ground should be protected from falling earth during and

after placing. 1oncrete placed in ground containing deleterious substances should be kept freefrom contact with such a ground and with water draining there from during placing and for a

period of seven days. )hen joint in a layer of concrete are unavoidable, and end is sloped at an

angle of (& and junctions of different layers break joint in laying upper layer of concrete. !helower surface is made rough and clean watered before upper layer is laid.

1:;9N< OF FOUN%:T9ON

4t our site, :aft foundations are used to spread the load from a structure over a large area,

normally the entire area of the structure. ormally raft foundation is used when large load is to

be distributed and it is not possible to provide individual footings due to space constraints that isthey would overlap on each other. :aft foundations have the advantage of reducing differential

settlements as the concrete slab resists differential movements between loading positions. !hey

are often needed on soft or loose soils with low bearing capacity as they can spread the loadsover a larger area.

#n laying of raft foundation, special care is taken in the reinforcement and construction of plinth

beams and columns. #t is the main portion on which ultimately whole of the structure load is to

come. ;o a slightest error can cause huge problems and therefore all this is checked and passed by the engineer in charge of the site.



4part from raft foundation, individual footings were used in the mess area which was e*tended beyond the 1 and D blocks.

CEMENT



8ortland cement is composed of calcium silicates and aluminate and aluminoferrite #t is obtained

by blending predetermined proportions limestone clay and other minerals in small quantities

which is pulveri"ed and heated at high temperature < around -%&& deg centigrade to produce=clinker2. !he clinker is then ground with small quantities of gypsum to produce a fine powder

called >rdinary 8ortland 1ement />813. )hen mi*ed with water, sand and stone, it combines

slowly with the water to form a hard mass called concrete. 1ement is a hygroscopic materialmeaning that it absorbs moisture #n presence of moisture it undergoes chemical reaction termed

as hydration. !herefore cement remains in good condition as long as it does not come in contact

with moisture. #f cement is more than three months old then it should be tested for its strength before being taken into use.

!he Bureau of #ndian ;tandards /B#;3 has classified >81 in three different grades !he

classification is mainly based on the compressive strength of cementsand mortar cubes of face

area %& cm composed of - part of cement to ( parts of standard sand by weight with a watercement ratio arrived at by a specified procedure. !he grades are

/i3 (( grade

/ii3 $( grade

/iii3 %( grade

!he grade number indicates the minimum compressive strength of cement sand mortar in

?mm at @ days, as tested by above mentioned procedure.

8ortland 8o""olana 1ement /8813 is obtained by either intergrinding a po""olanic material with

clinker and gypsum, or by blending ground po""olana with 8ortland cement. owadays good

quality fly ash is available from !hermal 8ower 8lants, which are processed and used inmanufacturing of 881.

:%=:NT:<ES OF US9N< PORT1:N% PO>>O1:N: CEMENT O=ER OPC

8o""olana combines with lime and alkali in cement when water is added and forms compounds

which contribute to strength, impermeability and sulphate resistance. #t also contributes to

workability, reduced bleeding and controls destructive e*pansion from alkaliaggregate reaction.#t reduces heat of hydration thereby controlling temperature differentials, which causes thermal

strain and resultant cracking n mass concrete structures like dams. !he colour of 881 comes

from the colour of the po""olanic material used. 881 containing fly ash as a po""olana will

invariably be slightly different colour than the >81.>ne thing should be kept in mind that is thequality 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. !he cement gets its colour from thenature 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. Aurther, the colour of the

finished concrete is affected also by the colour of the aggregates, and to a lesser e*tent by the

colour of the cement. 8reference for any cement on the basis of colour alone is technicallymisplaced.



SETT19N< OF CEMENT

)hen water is mi*ed with cement, the paste so formed remains pliable and plastic for a short

time. During this period it is possible to disturb the paste and remit it without any deleteriouseffects. 4s the reaction between water and cement continues, the paste loses its plasticity. !his

early period in the hardening of cement is referred to as =setting2 of cement.

9N9T9:1 :N% F9N:1 SETT9N< T9ME OF CEMENT

#nitial set is when the cement paste loses its plasticity and stiffens considerably. Ainal set is the

point when the paste hardens and can sustain some minor load. Both are arbitrary points andthese are determined by icat needle penetration resistance

;low or fast setting normally depends on the nature of cement. #t could also be due to e*traneous

factors not related to the cement. !he ambient conditions play an important role. #n hot weather,

the setting is faster, in cold weather, setting is delayed ;ome types of salts, chemicals, clay, etc if

inadvertently get mi*ed with the sand, aggregate and water could accelerate or delay the settingof concrete.

STOR:<E OF CEMENT

#t needs e*tra care or else can lead to loss not only in terms of financial loss but also in terms of

loss in the quality. Aollowing are the don2t that should be followed

/i3 Do not store bags in a building or a godown in which the walls, roof and floor are notcompletely weatherproof.



/ii3 Do not store bags in a new warehouse until the interior has thoroughly dried out.

/iii3 Do not be content with badly fitting windows and doors, make sure they fit properly and

ensure that they are kept shut.

/iv3 Do not stack bags against the wall. ;imilarly, don2t pile them on the floor unless it is a dryconcrete floor. #f not, bags should be stacked on wooden planks or sleepers.

/v3 Do not forget to pile the bags close together

/vi3 Do not pile more than -% bags high and arrange the bags in a headerandstretcher fashion.

/vii3 Do not disturb the stored cement until it is to be taken out for use.

/viii3 Do not take out bags from one tier only. ;tep back two or three tiers.

/i*3 Do not keep dead storage. !he principle of firstin firstout should be followed in removing bags.

/*3 Do not stack bags on the ground for temporary storage at work site. 8ile them on a raised, dry

platform and cover with tarpaulin or polythene sheet.

CO:RSE :<<RE<:TE

1oarse aggregate for the works should be river gravel or crushed stone .#t should be hard, strong,

dense, durable, clean, and free from clay or loamy admi*tures or quarry refuse or vegetable

matter. !he pieces of aggregates should be cubical, or rounded shaped and should have granular

or crystalline or smooth /but not glossy3 nonpowdery surfaces.4ggregates should be properlyscreened and if necessary washed clean before use.

1oarse aggregates containing flat, elongated or flaky pieces or mica should be rejected. !he

grading of coarse aggregates should be as per specifications of #;(@(.

4fter $hrs immersion in water, a previously dried sample of the coarse aggregate should not gain in

weight more than %C.

4ggregates should be stored in such a way as to prevent segregation of si"es and avoid

contamination with fines.

Depending upon the coarse aggregate color, there quality can be determined as9

3#ac7 ?@ -er. goo( Aua#it.

3#ue ?@ goo(



Whitish ?@6a( Aua#it.

F9NE :<<RE<:TE

4ggregate which is passed through $.% #; ;ieve is termed as fine aggregate. Aine aggregate is

added to concrete to assist workability and to bring uniformity in mi*ture. Esually, the natural

river sand is used as fine aggregate. #mportant thing to be considered is that fine aggregatesshould be free from coagulated lumps.

rading of natural sand or crushed stone i.e. fine aggregates shall be such that not more than %

percent shall e*ceed % mm in si"e, not more than -&C shall #; sieve o. -%& not less than $%C

or more than @%C shall pass #; sieve o. -.-@ mm and not less than %C or more than 6&C shall pass #; sieve o. 6&& micron.

3R9CWOR

Brickwork is masonry done with bricks and mortar and is generally used to build partition walls.

#n our site, all the e*ternal walls were of concrete and most of the internal walls were made of bricks. +nglish bond was used and a ration of -9$ /- cement9 $ coarse sand3 and -96 were used

depending upon whether the wall is $.% inches or F inches. !he reinforcement shall be nos.

G.;. round bars or as indicated. !he diameter of bars was @mm. !he first layer of reinforcement

was used at second course and then at every fourth course of brick work. !he bars were properlyanchored at their ends where the portions and or where these walls join with other walls. !he in

laid steel reinforcement was completely embedded in mortar.

Bricks can be of two types. !hese are9

-3 Tra(itiona# 3ric7s!he dimension if traditional bricks vary from - cm to %cm in length,-&to -( cm in width and .% cm in height in different parts of country .!he commonly adopted

normal si"e of traditional brick is ( ' --.%'.% cm with a view to achieve uniformity in si"e of

bricks all over country.

3 Mo(u#ar 3ric7s #ndian standard institution has established a standard si"e of bricks such a brick is known as a modular brick. !he normal si"e of brick is taken as &'-&'-& cm whereas its

actual dimensions are -F'F'F cm masonry with modular bricks workout to be cheaper there is

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

STREN<TB OF 3R9C M:SONR;

!he permissible compressive stress in brick masonry depends upon the following factors9

-. !ype and strength of brick.



. Gi* of motor.

(. ;i"e and shape of masonry construction.

!he strength of brick masonry depends upon the strength of bricks used in the masonry

construction. !he strength of bricks depends upon the nature of soil used for making and themethod 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 (&kg?sq cm to -%& kg ?sq cm the

basic compressive stress are different crushing strength.

!here are many checks that can be applied to see the quality of bricks used on the site.ormallythe bricks are tested for 1ompressive strength, water absorption, dimensional tolerances andefflorescence. However at small construction sites the quality of bricks can be assessed based on

following, which is prevalent in many sites.

isual check < Bricks should be well burnt and of uniform si"e and color.

;triking of two bricks together should produce a metallic ringing sound.

#t should have surface so hard that can2t be scratched by the fingernails.

4 good brick should not break if dropped in standing position from one metre above groundlevel.

4 good brick shouldn2t absorb moisture of more than -%&C by weight, when soaked in water

Aor e*ampleI a good brick of kg shouldn2t weigh more than .( to .$ kg if immersed inwater for $ hours.

PREC:UT9ONS TO 3E T:EN 9N 3R9C M:SONR; WOR



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

to its full thickness. ormally 6 to @ hours of wetting is sufficient.

4 systematic bond must be maintained throughout the brickwork. ertical joints

shouldn2t be continuous but staggered.

!he joint thickness shouldn2t e*ceed - cm. #t should be thoroughly filled with the

cement mortar -9$ to -96 /1ement9 ;and by volume3

4ll bricks should be placed on their bed with frogs on top /depression on top of the

brick for providing bond with mortar3.

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

hori"ontality of construction.

0oints should be raked and properly finished with trowel or float, to provide good bond.

4 ma*imum of one metre wall height should be constructed in a day.

Brickwork should be properly cured for at least -& days

RE9NFORCEMENT

;teel reinforcements are used, generally, in the form of bars of circular cross section in concrete

structure. !hey are like a skeleton in human body. 8lain concrete without steel or any other reinforcement is strong in compression but weak in tension. ;teel is one of the best forms of

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

Gild steel bars conforming to #;9 $( /8art #3 and 1oldworked steel high strength deformed bars

conforming to #;9 -@6 /grade Ae $-% and grade Ae %&&, where $-% and %&& indicate yieldstresses $-% ?mm and %&& ?mm respectively3 are commonly used. rade Ae $-% is being

used most commonly nowadays. !his has limited the use of plain mild steel bars because of

higher yield stress and bond strength resulting in saving of steel quantity. ;ome companies have

brought thermo mechanically treated /!G!3 and corrosion resistant steel /1:;3 bars with addedfeatures.

Bars range in diameter from 6 to %& mm. 1oldworked steel high strength deformed bars start

from @ mm diameter. Aor general house constructions, bars of diameter 6 to & mm are used



!ransverse reinforcements are very important. !hey not only take care of structural requirements

but also help main reinforcements to remain in desired position. !hey play a very significant role

while abrupt changes or reversal of stresses like earthquake etc.

!hey should be closely spaced as per the drawing and properly tied to the main?longitudinal

reinforcement

TERMS USE% 9N R E9NFORCEMENT

3:R 3EN%9N<SCBE%U1E

Barbendingschedule is the schedule of reinforcement bars prepared in advance before cuttingand bending of rebars. !his schedule contains all details of si"e, shape and dimension of rebars to

be cut.

1:P 1EN<TB

7ap length is the length overlap of bars tied to e*tend the reinforcement length.. 7ap length about

%& times the diameter of the bar is considered safe. 7aps of neighboring bar lengths should bestaggered and should not be provided at one level?line. 4t one cross section, a ma*imum of %&C

bars should be lapped. #n case, required lap length is not available at junction because of space

and other constraints, bars can be joined with couplers or welded /with correct choice of methodof welding3.

:NCBOR:<E 1EN<TB

!his is the additional length of steel of one structure required to be inserted in other at the

junction. Aor e*ample, main bars of beam in column at beam column junction, column bars infooting etc. !he length requirement is similar to the lap length mentioned in previous question or

as per the design instructions

CO=ER 31OC

1over blocks are placed to prevent the steel rods from touching the shuttering plates and there by providing a minimum cover and fi* the reinforcements as per the design drawings. ;ometimes it

is commonly seen that the cover gets misplaced during the concreting activity. !o 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 blocks3 is recommended. 1overs should be

made of cement sand mortar /-9(3. #deally, cover should have strength similar to the surroundingconcrete, with the least perimeter so that chances of water to penetrate through periphery will be

minimi"ed. 8rovision of minimum covers as per the #ndian standards for durability of the wholestructure should be ensured.

;hape of the cover blocks could be cubical or cylindrical. However, cover indicates thickness of

the cover block. ormally, cubical cover blocks are used. 4s a thumb rule, minimum cover of 5

in footings, -.%5 in columns and -5 for other structures may be ensured.



Structura# e#ement Co-er to rein&orcement )mm"

Footings $&

Co#umns $&

S#a6s -%

3eams %

Retaining 8a## % for earth face

& for other face

TB9N<S TO NOTE

:einforcement should be free from loose rust, oil paints, mud etc. it should be cut, bent and fi*ed

properly. !he reinforcement shall be placed and maintained in position by providing proper

cover blocks, spacers, supporting bars, laps etc. :einforcements shall be placed and tied such

that concrete placement is possible without segregation, and compaction possible by animmersion vibrator.

Aor any steel reinforcement bar, weight per running meter is equal to d'd?-6 Jg, where d is

diameter of the bar in mm. Aor e*ample, -& mm diameter bar will weigh -&K-&?-6 L &.6-

Jg?m

!hree types of bars were used in reinforcement of a slab. !hese include straight bars, crank bar

and an e*tra bar. !he main steel is placed in which the straight steel is binded first, then the crank

steel is placed and e*tra steel is placed in the end. !he e*tra steel comes over the support whilecrank is encountered at distance of M/-distance between the supports3 from the surroundings

supports.

Aor providing nominal cover to the steel in beam, cover blocks were used which were made of

concrete and were casted with a thin steel wire in the center which projects outward. !hese keepthe reinforcement at a distance from bottom of shuttering. Aor maintaining the gap between the

main steel and the distribution steel, steel chairs are placed between them

SBUTTER9N< :N% SC:FFO1%9N<



%EF9N9T9ON

!he term =;HE!!+:#2 or =A>:G)>:J2 includes all forms, moulds, sheeting, shuttering

planks, walrus, poles, posts, standards, lei"ers, Heads, struts, and structure, ties, prights,walling steel rods, bolts, wedges, and all other temporary supports to the concrete during the

process of sheeting.

FORM WOR

Aorms or moulds or shutters are the receptacles in which concrete is placed, so that it will have

the desired shape or outline when hardened. >nce the concrete develops adequate strength, theforms are removed. Aorms are generally made of the materials like timber, plywood, steel, etc.

enerally camber is provided in the formwork for hori"ontal members to counteract the effect of

deflection caused due to the weight of reinforcement and concrete placed over that. 4 proper lubrication of shuttering plates is also done before the placement of reinforcement. !he oil film

sandwiched between concrete and formwork surface not only helps in easy removal of shuttering but also prevents loss of moisture from the concrete through absorption and evaporation.

!he steel form work was designed and constructed to the shapes, lines and dimensions shown onthe drawings. 4ll forms were sufficiently water tight to prevent leakage of mortar. Aorms were so

constructed as to be removable in sections. >ne side of the column forms were left open and the

open side filled in board by board successively as the concrete is placed and compacted e*cept



when vibrators are used. 4 key was made at the end of each casting in concrete columns of

appropriate si"e to give proper bondings to columns and walls as per relevant #;.

C1E:N9N< :N% TRE:TMENT OF FORMS

4ll rubbish, particularly chippings, shavings and saw dust, was removed from the interior of the

forms /steel3 before the concrete is placed. !he form work in contact with the concrete was

cleaned and thoroughly wetted or treated with an approved composition to prevent adhesion between form work and concrete. 1are was taken that such approved composition is kept out of

contact with the reinforcement.

%ES9<N

!he formwork should be designed and constructed such that the concrete can be properly placedand thoroughly compacted to obtain the required shape, position, and levels subject

ERECT9ON OF FORMWOR

!he following applies to all formwork9

a3 1are should be taken that all formwork is set to plumb and true to line and level.

b3 )hen 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 the compaction of



concrete.

c3 #f formwork is held together by bolts or wires, these should be so fi*ed that no iron is

e*posed on surface against which concrete is to be laid.

d3 8rovision is made in the shuttering for beams, columns and walls for a port hole of

convenient si"e so that all e*traneous materials that may be collected could be

removed just prior to concreting.

e3 Aormwork is so arranged as to permit removal of forms without jarring the concrete.

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

f3 ;urfaces of forms in contact with concrete are oiled with a mould oil of approved

quality. !he use of oil, which darkens the surface of the concrete, is not allowed. >iling

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

the reinforcement while it is placed in position. !he formwork is kept thoroughly wet

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

9mme(iate#. 6e&ore concreting is commence(+ the &orm8or7 is care&u##. examine( to

ensure the &o##o8ingD

a3 :emoval of all dirt, shavings, sawdust and other refuse by brushing and washing.

b3 !he tightness of joint between panels of sheathing and between these and any hardened core.

c3 !he correct location of tie bars bracing and spacers, and especially connections of

bracing.

d3 !hat all wedges are secured and firm in position.

e3 !hat provision is made for traffic on formwork not to bear directly on reinforcement

steel.

=ERT9C:19T; OF TBE STUCTURE



4ll the outer columns of the frame were checked for plumb by plumbbob as the work proceeds

to upper floors. #nternal columns were checked by taking measurements from outer row of

columns for their e*act position. 0ack were used to lift the supporting rods called props

STR9PP9N< T9ME OR REMO=:1 OF FORMWOR

Aorms were not struck until the concrete has attained a strength at least twice the stress to which

the concrete may be subjected at the time of removal of form work. !he strength referred is that

of concrete using the same cement and aggregates with the same proportions and cured under conditions of temperature and moisture similar to those e*isting on the work. )here so required,

form work was left longer in normal circumstances

Aorm 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 e*posed to ascertain that theconcrete has sufficiently hardened. )here the shape of element is such that form work has re

entrant angles, the form work was removed as soon as possible after the concrete has set, to

avoid shrinkage cracking occurring due to the restraint imposed. 4s a guideline, withtemperature above & degree following time limits should be followed9

Structura# Component :ge

Footings - day

Si(es o& 6eams+ co#umns+ #inte#s+ 8a## days

Un(ersi(e o& 6eams spanning #ess than 0m -$ days

Un(ersi(e o& 6eams spanning o-er 0m - days

Un(ersi(e o& s#a6s spanning #ess than ,m days

Un(ersi(e o& s#a6s spanning more than ,m -$ days

F#at s#a6 6ottom - days

posted in 8roject :eports N @ 1omments

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Project Report – Six Months Summer Training

CONCRET9N<

1oncrete is a mi*ture of cement, sand, stone aggregates and water. 4 cage of steel rods usedtogether with the concrete mi* leads to the formation of :einforced 1ement 1oncrete popularly

known as :11.

1oncrete has two main stages

-3 Aresh 1oncrete

3 Hardened 1oncrete

Aresh 1oncrete should be stable and should not segregate or bleed during transportation and

placing when it is subjected to forces during handling operations of limited nature. !he mi*should be cohesive and mobile enough to be placed in the form around the reinforcement and

should be able to cast into the required shape without loosing continuity or homogeneity under the available techniques of placing the concrete at a particular job. !he mi* should be amenable

to proper and through compaction into a dense, compact concrete with minimum voids under the

e*isting facilities of compaction at the site. 4 best mi* from the point of view of campactibilityshould achieve a FF percent elimination of the original voids present.

SE<RE<:T9ON

!he stability of a concrete mi* requires that it should not segregate and bleed during the

transportation and placing. ;egregation can be defined as separating out of the ingredients of aconcrete mi*, so that the mi* is no longer in a homogeneous condition. >nly the stable

homogeneous mi* can be fully compacted

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!he segregation depends upon the handling and placing operations. !he tendency to segregate,

amount of coarse aggregate, and with the increased slump. !he tendency to segregate can be

minimi"ed by9

a. :educing the height of drop by concrete.

b. ot using the vibration as a means of spreading a heap of of concrete into a level mass over a largearea.

c. :educing the continued vibration over a longer time, as the coarse aggregate tends to settle to the

bottom and the scum would rise to the surface.

d. 4dding small quantity of water which improves cohesion of the mi*.

31EE%9N<

Bleeding is due to the rise of water in the mi* to the surface because of the inability of the solid

particles in the mi* to hold all the mi*ing water during settling of particles under the effect of

compaction. !he bleeding causes formation of a porous, weak and non durable concrete layer at

the top of placed concrete. #n case of lean mi*es bleeding may create capillary channelsincreasing the permeability of the concrete. )hen the concrete is placed in different layers and

each layer is compacted after allowing certain time to lapse before the ne*t layer is laid, the bleeding may cause a plane of weakness between two layers. 4ny laitance formed should beremoved by brushing and washing before a new layer is added. >ver compacting the surface

should be avoided.

B:R%ENE% CONCRETE



>ne of the most important properties of the hardened concrete is its strength which represents the

ability if concrete to resist forces. #f the nature of the force is to produce compression, the

strength is termed compressive strength. !he compressive strength of hardened concrete isgenerally considered to be the most important property and is often taken as the inde* of the

overall quality of concrete. !he strength can indirectly give an idea of the most of the other

properties of concrete which are related directly to the structure of hardened cement paste. 4stronger concrete is dense, compact, impermeable and resistant to weathering and to some

chemicals. However, a stronger concrete may e*hibit higher drying shrinkage with consequent

cracking, due to the presence of higher cement content.

;ome of the other desirable properties like shear and tensile strengths, modulus of elasticity, bond, impact and durability etc. are generally related to compressive strength. 4s the

compressive strength can be measured easily on standard si"ed cube or cylindrical specimens, it

can be specified as a criterion for studying the effect of any variable on the quality of concrete.However, the concrete gives different values of any property under different testing conditions.

Hence method of testing, si"e of specimen and the rate of loading etc. are stipulated while testing

the concrete to minimi"e the variations in test results. !he statistical methods are commonly usedfor specifying the quantitative value of any particular property of hardened concrete.

COMPRESS9=E STREN<TB

!he compressive strength of concrete is defined as the load which causes the failure of specimen,

per unit area of crosssection in unia*ial compression under given rate of loading. !he strength

of concrete is e*pressed as ?mm. !he compressive strength at @ days after casting is taken asa criterion for specifying the quality of concrete. !his is termed as grade of concrete. #; $%6 <

&&& stipulates the use of -%& mm cubes.

TENS91E STREN<TB

!he concrete has low tensile strengthI it ranges from @- per cent of its compressive strength.4n average value of -& per cent is generally adopted.

SBE:R STREN<TB

!he concrete subjected to bending and shear stress is accompanied by tensile and compressive

stresses. !he shear failures are due to resulting diagonal tension. !he shear strength is generally

--( per cent of its compressive strength.

3ON% STREN<TB

!he resistance of concrete to the slipping of reinforcing bars embedded in concrete is called bond

strength. !he bond strength is provided by adhesion of hardened cement paste, and by the

friction of concrete and steel. #t is also affected by shrinkage of concrete relative to steel. >n anaverage bond strength is taken as -& per cent of its compressive strength.

F:CTS :3OUT CEMENT :N% CONCRETE



-3 )ater required by - bag of cement is something in the range of %@ litres

3 Ouality of concrete has nothing to do with its color.

(3 !he mortar ? concrete should be consumed as early as possible after addition of water to it.

!he hydration of cement starts the moment water is added to it. 4s the hydration progresses thecement paste starts stiffening and loses its plasticity. !he concrete should not be disturbed after

this. ormally, this is about $% < %& minutes.

$3 G8a is abbreviated form of mega 8ascal, which is a unit of pressure. - G8a is equivalent to a

pressure of -&Jg ?cm. !he strength of concrete P cement is e*pressed in terms of pressure astandard cube can withstand. !he >rdinary 8ortland 1ement, commonly called >81 is available

in three grades namely ((, $( P %( grades. !hus, for $( grade cement standard cement P sand

mortar cube would give a minimum strength of $( G8a or $(& Jg ?cm when tested under standard curing conditions for @ days.

COMPRESS9=E STREN<TB OF CONCRETE %EPEN%S ON FO11OW9N< F:CTORS

/i3 w?c ratio

/ii3 1haracteristics of cement

/iii3 1haracteristics of aggregates

/iv3 !ime of mi*ing

/v3 Degree of compaction

/vi3 !emperature and period of curing

/vii3 4ge of concrete

/viii34ir entertainment

/i*3 1onditions of testing

PREC:UT9ONS FOR W:TER TO 3E USE% 9N CONCRETE

#t is good to use potable quality of water.

#t should be free from impurities and harmful ingredients.

;eawater isn2t recommended.

!he water fit for mi*ing is fit for curing too



Ese of minimum quantity of mi*ing water, consistent with the degree of workability required

to enable easy placing and compaction of concrete, is advisable.

+nsure that water is measured and added.

7ow water to cement ratio is essential for good performance of the structure in the long run.

COMMON R E:SONS FOR 1:C OF QU:19T; 9N CONCRETE WOR

Ese of too much or too little water for mi*ing, or water carelessly added during mi*ing

#ncomplete mi*ing of aggregate with cement

#mproper grading of aggregates resulting in segregation or bleeding of concrete.

#nadequate compaction of concrete

Esing concrete which has already begun to set.

8lacing of concrete on a dry foundation without properly wetting it with water.

Ese of dirty aggregate or water containing earthy matter, clay or lime.

!oo much troweling of the concrete surface.

7eaving the finished concrete surface e*posed to sun and wind during the first ten days after

placing without protecting it and keeping it damp by proper methods of curing.

1onstruction joints are the joints provided between successive pours of concrete that have been

carried out after a time lag. 4s far as possible the construction joints should be avoided and everycare should be taken to keep their numbers minimal. ;ince, presence of these joints creates a

plane of weakness within the concrete body, these joints should be preplanned and their location

should be such that they are at places where they are subjected to minimum bending moment andminimum shear force.

POUR9N< :N% CONSO19%:T9ON

1oncrete /G&3 was used for all works in column, beams and slabs. #t was well consolidated by

vibrating using portable mechanical vibrators. 1are was taken to ensure that concrete is not over vibrated so as to cause segregation. !he layers of concrete are so placed that the bottom layer

does not finally set before the top layer is placed. !he vibrators maintain the whole of concrete

under treatment in an adequate state of agitation, such that deaeration and effective compaction is

attained at a state commensurate with the supply of concrete from the mi*ers. !he vibrator continue during the whole period occupied by placing of concrete, the vibrators being adjusted

so that the centre vibrations appro*imate to the centre of the mass being compacted at the time of

placing. ;haking of reinforcement for the purpose of compaction should be avoided. 1ompaction



shall be completed before initial setting starts i.e. within thirty minute of addition of water to the

dry mi*ture.

!he concrete was deposited in its final position in a manner to preclude segregation of ingredients.#n case of column and walls, the shuttering was so adjusted that the vertical drop of concrete is

not more than -.% m at a time. #n case of concreting of slabs and beams, the pipe from the batching plant was directly taken to the closest point.

COMP:CT9ON

reen concrete has all the three phases < solids, water P air. #n order to make the concreteimpervious P attain its ma*imum strength it is required to remove the entrapped air from the

concrete mass when it is still in plastic state. #f the air is not removed completely, the concrete

loses strength considerably. #t has been observed that %C voids reduce the strength by about (&Cand -&C voids reduce the strength by over %&C. 1ompaction eliminates air bubbles and brings

enough fine material both to the surface and against the forms to produce the desired finish. >ne

can use such hand tools as steel rods, paddling sticks, or tampers, but mechanical vibrators are best. 4ny compacting device must reach the bottom of the form and be small enough to pass

between reinforcing bars. ;ince the strength of the concrete member depends on proper

reinforcement location, be careful not to displace the reinforcing steel.

1 1ompacting reinforced concrete work is very important and is done using iron rods. #n case thethickness of concrete layers should be more than -% cm. the most satisfactory method for

compacting concrete properly is to consolidate each layer separately so that its top surface

become level and fairy smooth before the ne*t layer is placed. )hile tamping is carried out, careshould be taken that the rod should penetrate the full layer of the last layer placed and to some

e*tent into lying to ensure proper bond between bond between them. ;econdly the reinforcement

and formwork should not be disturbed from their positions.

MECB:N9C:1 COMP:CT9ON

G Gechanical compaction is done by the use of vibrators. 1ompaction of concrete by vibration isconsidered essential for all important works especially in situations where reinforcements are

congested or the member is required is to have e*posed to concrete surface finish. )hen

vibraters are used leaner but stiff, concrete mi* should be used to obtain greater durability andhighest strength, mi*es which are to stiff to consolidate by hand compaction can be easily

compacted by mechanical compaction, in case the concrete is compacted by vibrations ,during

which the vibrator communicates rapid vibrations to the particles, increases the fluidity of

concrete. Due to vibrations the particles occupy a more stable position and concrete fills all thespace and present is force out to the surface, resulting in dense and durable concrete.

T;PES OF =93R:TORS

Aollowing are the type of vibrates usually used to compact concrete9

-. #nternal vibrators



. +*ternal vibrators

(. ;urface vibrators

$. ibrating table

#nternal vibrator consists of metal road like vibrating head which is immersed in the full depth of concrete layer. #t is also known as poker or needle vibrator and is consider to be most effective

type of vibrator as it comes into intimate contact with concrete. +*ternal vibrators are placed

against the concrete formwork and vibrating force for compaction is conveyed to the concrete

through the form work. !hese vibrators are also called form vibrators. !he vibrator is rigidlyclamped to form work resting on a elastic spot, so that both the form and concrete are vibrated.

#ncase considerable proportion of work done is consumed in vibrating resulting in low efficiency

of the system. ;urface vibrators are mounted on platform and are generally used to compact andfinish bridge, road slab etc. !hese are also e*ternal vibrators and are suitable for precast concrete

work. #t provides a reliable means of compaction of precast concrete and has the adv of offering

uniform vibration. ibrating table is used for consolidation of precast units. ;urface vibrators isused there a wide hori"ontal surface occurs such as dams and very thick walls .large type of

surface vibrators is there but pen type vibrator are used most. )hen concrete is placed on such

tables, mechanical compaction takes place which has many advantages. +ach vibrator have its

own advantages and disadvantages, hence the choice between different types should be madecorrectly. 1oncrete to be compacted by vibration, should be designed properly. !he consistency

of concrete depends of conditions of placing, type of mi*, and the efficiency of vibrator. !he

slum of such concrete should not be more than % cm in any caseI otherwise segregation of concrete will take place, which should never be allowed to occur.

F9N9SB TO CONCRETE WOR9

a3 4ll concrete while being poured against form work was worked with vibrator

rods P trowels as required so that good quality concrete is obtained.

b3 4ll e*posed surface of :11 lintels, beams, columns etc. were plastered to match

with adjoining plastered face of walls after suitably hacking the concrete surface.

CONCRETE M9ERS :N% 3:TCB9N< P1:NT

1oncrete 8lant, also known as a Batch 8lant, is a device that combines various ingredients toform concrete. ;ome of these inputs include sand, water, aggregate /rocks, gravel, etc.3, fly ash,

potash, cement, and other ingredients to create concrete. !here are two types of concrete plants,ready mi* plants and central mi* plant. 4 concrete plant can have a variety of parts and

accessories, including but not limited to9 mi*ers /either tiltup or hori"ontal /or in some cases,

both3, cement batchers, aggregate batchers, conveyors, radial stackers, aggregate bins, cement

bins, heaters, chillers, cement silos, batch plant controls, and dust collectors /to minimi"eenvironmental pollution3.



!he front view of the plant from where it hauls coarse aggregate is shown below9

CUR9N<

!he term =curing2 is used to include maintenance of a favorable environment for the continuationof chemical reactions, i.e. retention of moisture within, or supplying moisture to the concrete

from an e*ternal source and protection against e*tremes of temperature

Aollowing are the methods for curing different building parts9

Wa##s < )ater should be sprinkled from the top such that it covers the whole area of the wall andit should be remain wet.



S#a6 < 8onding should be done on the slab by constructing bunds of mortar

3eams an( co#umns < !he beams and columns can be maintained wet by tying gunny bags

around the periphery and by maintaining it wet always.

8onding, continuous sprinkling, covering with wet cloth, cotton mats or similar materials,covering with specially prepared paper, polyethylene, sealing coat applied as a liquid commonly

known as =curing compound2 which hardens to form a thin protective membrane, are some of the

methods by which concrete is cured. 1uring should be started just after the surfaces begin to dry. ormally to -$ days curing is considered adequate.

:%M9TURE

4dmi*tures are those ingredients?materials that are added to cement, water, and aggregate

mi*ture during mi*ing in order to modify or improve the properties of concrete for a required

application.

3roa(#. the &o##o8ing &i-e changes can 6e expecte( 6. a((ing an a(mixture

/i3 4ir entertainment

/ii3 )ater reduction for better quality

/iii3 4cceleration of strength development

/iv3 #mproving the workability

/v3 )ater retention

Some o& the important purposes &or 8hich the a(mixtures cou#( 6e use( are

-. 4cceleration of the rate of strength development at early ages

. :etardation of the initial setting of the concrete

(. #ncrease in strength

$. #mprovement in workability

%. :eduction in heat of evolution

6. #ncrease in durability or in resistance to special conditions of e*posure

. 1ontrol of alkaliaggregate e*pansion

@. :eduction in the capillary flow of water and increase in impermeability to liquids



F. #mprovement of pumpability and reduction in segregation in grout mi*tures

-&. 8roduction of coloured concrete or mortar

!he best way to test the admi*ture is by making trial mi*es with the concrete materials to be

used on the job and carefully observing and measuring the change in the properties. !his way thecompatibility of the admi*ture and the materials to be used, as well the effects of the admi*ture

on the properties of fresh and hardened concrete can be observed. !he amount of admi*ture

recommended by the manufacturer or the optimum quantity determined by laboratory testsshould be used

1E::<E :N% W:TER PROOF9N<

!here are many reasons for leakage in concrete. Due to this leakage, the concrete not only loosesits strength but also cause problem to the user. ormal concrete construction should not require

water proofing materials, if it is designed and constructed properly with good quality and

workmanship. But still to make it safe against the ill effects of water, liquid and powder form of water proofing material is used depending upon the availability of the material. ormally theusage per kg of cement is specified by the manufacturer for e*ample9 4112s waterproofing

compound Q411>8:>>A5 is available in powder form and - Jg packets. Aor normal purposes,

- Jg is required to be used with %& Jg /- bag3 of cement.

7eakages occur because of variety of reasonsI some of which are mentioned below <

a3 4ccumulation of water, which start penetrating the surface.

b3 8oor quality and improper proportioning of concrete constituents that make concrete

permeable.



c3 8oor compaction of concrete, which leave a lot of air voids.

d3 1onstruction joints at two different works like concrete and brick works, and discontinuity in

concrete casting /joint at old concrete and new concrete3 leading minute cracks, whichfacilitate water movement.

e3 >ther structural cracks because of loading conditions and failure of the structure to withstand

those stresses.

f3 Govement of water from bottom to top because of capillary action.

Aollowing figure shows the damp proofing material which was used at site9

Fo##o8ing measures ma. 6e use&u# to a-oi( #ea7ages –

a3 8rovide good drainage facility with correct gradient at the places where there are chances for

water to accumulate.

b3 Ese good quality of materials with correct proportioning in concrete. Aor e*ample, use of

blended cement and use of less water in concrete can reduce permeability of the structure.;imilarly, proper proportioning of materials would help concrete becoming uniformly packed

and dense.

c3 8roper compaction of concrete with immersion vibrator to make it void less.

d3 4void construction joints becoming a weaker point for water to travel. ;ome proactive and

treatment measures would be useful.

e3 8roper structural design and e*ecution of members, which results no cracks for water to

percolate.

f3 8roper damp proofing course required to avoid movement of ground and other water from

bottom to top. ;ome useful methods are like applying bitumen, concrete construction etc. at plinth level.

g3 Ese of water proofing compounds for water retaining structures.

%OORS :N% W9N%OWS

)ood absorbs moisture from air when the moisture content is high in the atmosphere and as aresult it e*pands causing cracks in the wall. During dry atmosphere the wood contracts and a gap

is formed between the wall and the frame of the door.

P1:STER9N<



8laster protects structure from temperature variationsI e*ternal attacks of sulphates, chlorides,

etc. 8laster also provides smooth P aesthetic surface on :11 P Brickwork surface. !he

proportion of mortar used at site for ceiling coat is -9$ and wall coat is -9(. 4 plaster of -& mm isdone at ceiling and a plaster of -.%mm is done at wall. arious precautions to be taken while the

work of plastering is going on are9

8referably use cements which releases low heat of hydration.

Ese optimum water at the time of mi*ing.

Do not use dry cement on the plaster surface.

4t the junction of Brickwork P :11, chicken mesh or fiber mesh may be used.

)et the surface before plastering and cure the surface for at least -& to - days.

F1OOR9N<

!he purpose of a floor is to provide a hori"ontal sanitary surface to support the occupants of a building, furniture and equipment. 4 good floor should have strength and stability, resistance to

dampness, good appearance, and freedom from maintenance etc.

Aollowing are the common floor finishes <

Cement concrete &#ooring #t consists of -9-.%9( cement concrete laid to a thickness of (5 to $5,over a strong sub base. !op surface is smoothened with cement punning. #t has got good wearing

properties and can be easily cleaned and maintained. #f thickness is less, the si"e of stone

aggregates is limited to R5.

Ti#e &#ooring #t consists of ceramic, vitrified, terra""o and cement tiles. !iles give very pleasantappearance to floors. 4lso, it can be e*ecuted fast. itrified and 1eramic tiles have gained

popularity over mosaic tiles because it doesn2t require grinding and polishing and the appearance

is good and the tiles are quite strong.

#n ground floor the cement concrete floor is to be on .% cm base of lime concrete or weak cement concrete as per standard specifications. #f the bases consist of cement concrete it shall be

allowed to set for about days. #n case the base is of weak cement concrete the flooring shall

commence within $@ hours of laying the base. #n first floor or upper floor if c.c. floor is to be laid

on :.1.1. slab, the surface shall be made rough with brushes while concrete is green. Beforelaying the c.c. floor the surface shall be cleaned, wetted and a neat cement wash shall be applied

to get a good bond.4 layer of brick brats ie broken bricks are laid before the laying of mortar and

there by the tiles

E1ECTR9C:1 CON%U9TS

;eparate conduits are laid for following systems9



a3 ormal light, fan

b3 8ower points

c3 41 points

d3 #nternet wiring

e3 Aire alarm system

Concrete Mix %esign :s Per 9n(ian Stan(ar( Co(e

Concrete Mix %esign

9ntro(uction

!he process of selecting suitable ingredients of concrete and determining their relative amountswith the objective of producing a concrete of the required, strength, durability, and workability as

economically as possible, is termed the concrete mi* design. !he proportioning of ingredient of

concrete is governed by the required performance of concrete in states, namely the plastic and

the hardened states. #f the plastic concrete is not workable, it cannot be properly placed andcompacted. !he property of workability, therefore, becomes of vital importance.

!he compressive strength of hardened concrete which is generally considered to be an inde* of

its other properties, depends upon many factors, e.g. quality and quantity of cement, water andaggregatesI batching and mi*ingI placing, compaction and curing. !he cost of concrete is made

up of the cost of materials, plant and labour. !he variations in the cost of materials arise from thefact that the cement is several times costly than the aggregate, thus the aim is to produce as lean a

mi* as possible. Arom technical point of view the rich mi*es may lead to high shrinkage andcracking in the structural concrete, and to evolution of high heat of hydration in mass concrete

which may cause cracking.

!he actual cost of concrete is related to the cost of materials required for producing a minimum

mean strength called characteristic strength that is specified by the designer of the structure. !hisdepends on the quality control measures, but there is no doubt that the quality control adds to the

cost of concrete. !he e*tent of quality control is often an economic compromise, and depends on

the si"e and type of job. !he cost of labour depends on the workability of mi*, e.g., a concrete

mi* of inadequate workability may result in a high cost of labour to obtain a degree of compaction with available equipment.

ReAuirements o& concrete mix (esign

!he requirements which form the basis of selection and proportioning of mi* ingredientsare 9

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a 3 !he minimum compressive strength required from structural consideration

b3 !he adequate workability necessary for full compaction with the compacting

equipment available.

c3 Ga*imum watercement ratio and?or ma*imum cement content to give adequatedurability for the particular site conditions

d3 Ga*imum cement content to avoid shrinkage cracking due to temperature cycle in

mass concrete.

T.pes o& Mixes

! Nomina# Mixes

#n the past the specifications for concrete prescribed the proportions of cement, fine and

coarse aggregates. !hese mi*es of fi*ed cementaggregate ratio which ensures adequatestrength are termed nominal mi*es. !hese offer simplicity and under normal

circumstances, have a margin of strength above that specified. However, due to thevariability of mi* ingredients the nominal concrete for a given workability varies widely

in strength.

$ Stan(ar( mixes

!he nominal mi*es of fi*ed cementaggregate ratio /by volume3 vary widely in strength and mayresult in under or overrich mi*es. Aor this reason, the minimum compressive strength has been

included in many specifications. !hese mi*es are termed standard mi*es.

#; $%6&&& has designated the concrete mi*es into a number of grades as G-&, G-%, G&,

G%, G(&, G(% and G$&. #n this designation the letter G refers to the mi* and the number tothe specified @ day cube strength of mi* in ?mm . !he mi*es of grades G-&, G-%, G& and

G% correspond appro*imately to the mi* proportions /-9(963, /-99$3, /-9-.%9(3 and /-9-93

respectively.

' %esigne( Mixes

#n these mi*es the performance of the concrete is specified by the designer but the mi*

proportions are determined by the producer of concrete, e*cept that the minimum cement content

can be laid down. !his is most rational approach to the selection of mi* proportions with specificmaterials in mind possessing more or less unique characteristics. !he approach results in the

production of concrete with the appropriate properties most economically. However, the

designed mi* does not serve as a guide since this does not guarantee the correct mi* proportions

for the prescribed performance.

Aor the concrete with undemanding performance nominal or standard mi*es /prescribed in the

codes by quantities of dry ingredients per cubic meter and by slump3 may be used only for very



small jobs, when the @day strength of concrete does not e*ceed (& ?mm . o control testing

is necessary reliance being placed on the masses of the ingredients.

Factors a&&ecting the choice o& mix proportions

!he various factors affecting the mi* design are9

! Compressi-e strength

#t is one of the most important properties of concrete and influences many other describable

properties of the hardened concrete. !he mean compressive strength required at a specific age,

usually @ days, determines the nominal watercement ratio of the mi*. !he other factor affectingthe strength of concrete at a given age and cured at a prescribed temperature is the degree of

compaction. 4ccording to 4braham2s law the strength of fully compacted concrete is inversely

proportional to the watercement ratio.

$ Wor7a6i#it.

!he degree of workability required depends on three factors. !hese are the si"e of the section to be concreted, the amount of reinforcement, and the method of compaction to be used. Aor the

narrow and complicated section with numerous corners or inaccessible parts, the concrete must

have a high workability so that full compaction can be achieved with a reasonable amount of effort. !his also applies to the embedded steel sections. !he desired workability depends on the

compacting equipment available at the site.

' %ura6i#it.

!he durability of concrete is its resistance to the aggressive environmental conditions. Highstrength concrete is generally more durable than low strength concrete. #n the situations when the

high strength is not necessary but the conditions of e*posure are such that high durability is vital,

the durability requirement will determine the watercement ratio to be used.

, Maximum nomina# siGe o& aggregate

#n general, larger the ma*imum si"e of aggregate, smaller is the cement requirement for a particular watercement ratio, because the workability of concrete increases with increase in

ma*imum si"e of the aggregate. However, the compressive strength tends to increase with the

decrease in si"e of aggregate.

#; $%69&&& and #; -($(9-F@& recommend that the nominal si"e of the aggregate should be aslarge as possible.

/ <ra(ing an( t.pe o& aggregate



!he grading of aggregate influences the mi* proportions for a specified workability and water

cement ratio. 1oarser the grading leaner will be mi* which can be used. ery lean mi* is not

desirable since it does not contain enough finer material to make the concrete cohesive.

!he type of aggregate influences strongly the aggregatecement ratio for the desired workability

and stipulated water cement ratio. 4n important feature of a satisfactory aggregate is theuniformity of the grading which can be achieved by mi*ing different si"e fractions.

0 Qua#it. Contro#

!he degree of control can be estimated statistically by the variations in test results. !he variationin strength results from the variations in the properties of the mi* ingredients and lack of control

of accuracy in batching, mi*ing, placing, curing and testing. !he lower the difference between

the mean and minimum strengths of the mi* lower will be the cementcontent required. !hefactor controlling this difference is termed as quality control.

Mix Proportion (esignations

!he common method of e*pressing the proportions of ingredients of a concrete mi* is in the

terms of parts or ratios of cement, fine and coarse aggregates. Aor e.g., a concrete mi* of proportions -99$ means that cement, fine and coarse aggregate are in the ratio -99$ or the mi*

contains one part of cement, two parts of fine aggregate and four parts of coarse aggregate. !he

proportions are either by volume or by mass. !he watercement ratio is usually e*pressed in

mass

Factors to 6e consi(ere( &or mix (esign

!he grade designation giving the characteristic strength requirement of concrete.

!he type of cement influences the rate of development of compressive strength of concrete.

Ga*imum nominal si"e of aggregates to be used in concrete may be as large as possible within the

limits prescribed by #; $%69&&&.

!he cement content is to be limited from shrinkage, cracking and creep.

!he workability of concrete for satisfactory placing and compaction is related to the si"e and shape

of section, quantity and spacing of reinforcement and technique used for transportation, placing

and compaction.

Proce(ure

-. Determine the mean target strength f t from the specified characteristic compressive strength at @

day f ck and the level of quality control.

f t L f ck S -.6% ;



where ; is the standard deviation obtained from the !able of appro*imate contents given after the

design mi*.

. >btain the water cement ratio for the desired mean target using the emperical relationship betweencompressive strength and water cement ratio so chosen is checked against the limiting water

cement ratio. !he water cement ratio so chosen is checked against the limiting water cement ratiofor the requirements of durability given in table and adopts the lower of the two values.

(. +stimate the amount of entrapped air for ma*imum nominal si"e of the aggregate from the table.

$. ;elect the water content, for the required workability and ma*imum si"e of aggregates /for aggregates in saturated surface dry condition3 from table.

%. Determine the percentage of fine aggregate in total aggregate by absolute volume from table for

the concrete using crushed coarse aggregate.

6. 4djust the values of water content and percentage of sand as provided in the table for anydifference in workability, water cement ratio, grading of fine aggregate and for rounded

aggregate the values are given in table.

. 1alculate the cement content form the watercement ratio and the final water content as arrived

after adjustment. 1heck the cement against the minimum cement content from the requirementsof the durability, and greater of the two values is adopted.

@. Arom the quantities of water and cement per unit volume of concrete and the percentage of sand

already determined in steps 6 and above, calculate the content of coarse and fine aggregates per

unit volume of concrete from the following relations9

where L absolute volume of concrete

L gross volume /-m( 3 minus the volume of entrapped air

;c L specific gravity of cement

) L Gass of water per cubic metre of concrete, kg

1 L mass of cement per cubic metre of concrete, kg

p L ratio of fine aggregate to total aggregate by absolute volume



f a, 1a L total masses of fine and coarse aggregates, per cubic metre of concrete,

respectively, kg, and

;fa, ;ca L specific gravities of saturated surface dry fine and coarse aggregates,respectively

F. Determine the concrete mi* proportions for the first trial mi*.

-&. 8repare the concrete using the calculated proportions and cast three cubes of -%& mm si"e and

test them wet after @days moist curing and check for the strength.

--. 8repare trial mi*es with suitable adjustments till the final mi* proportions are arrived at.

posted in 8roject :eports N F@ 1omments

Tests Con(ucte( To Chec7 Qua#it. O& Concrete

TEST CON%UCTE% ON S9TE FOR QU:19T; CONTRO1

S1UMP TEST

!his is a site test to determine the workability of the ready mi*ed concrete just before its placingto final position inside the formwork, and is always conducted by the supervisor on site.

However in mid of concreting process , should the site supervisor visually finds that the green

concrete becomes dry or the placement of concrete has been interrupted , a retest on theremaining concrete should be conducted in particular of the pour for congested reinforcement

area . !he procedure of test in brief is as follows9

-. +nsure the standard ;lump 1one and associated equipment are clean before test and free fromhardened concrete.

. )et the ;lump 1one and drain away the superfluous water.

(. :equest the mi*er or concrete truck to well mi* the concrete for additional % minutes.

$. 8lace the ;lump 1one on one side / i.e. not in middle 3 of the base plate on leveled ground andstand with feet on the footpieces of cone .

%. Esing a scoop and fill the cone with sampled concrete in ( equal layers, each of about -&&mm

thick.6. 1ompact each layer of concrete in turn e*actly % times with a ;lump :od, allowing the rod

just passes into the underlying layer.

. )hile tamping the top layer, top up the cone with a slight surcharge of concrete after thetamping operation.

@. 7evel the top by a Qsawing and rolling5 motion of the ;lump :od across the cone.

F. )ith feet are still firmly on the footpieces, wipe the cone and base plate clean and removeany leaked concrete from bottom edge of the ;lump 1one.

-&. 7eave the footpieces and lift the cone carefully in a vertical up motion in a few seconds

time.

--. #nvert the cone on other side and ne*t to the mound of concrete.


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-. 7ay the ;lump :od across the inverted cone such that it passes above the slumped concrete at

its highest point.

-(. Geasure the distance between the underside of rod and the highest point of concrete to thenearest %mm.

-$. !his reading is the amount that the sampled concrete has slumped.

-%. #f the concrete does not show an acceptable slump, repeat the test with another sample.-6. #f the repeated test still does not show an acceptable slump, record this fact in the report, or

reject that load of concrete.

COMPRESS9ON TEST

!he 1ompression !est is a laboratory test to determine the characteristic strength of the concrete but the making of test cubes is sometimes carried out by the supervisor on site. !his cube test

result is very important to the acceptance of insitu concrete work since it demonstrates the

strength of the design mi*.

!he procedure of making the test cubes is as follows9

-. -%& mm standard cube mold is to be used for concrete mi* and -&& mm standard cube mold is

to be used for grout mi*.

. 4rrange adequate numbers of required cube molds to site in respect with the sampling

sequence for the proposed pour.(. Gake sure the apparatus and associated equipment / see Aig < 6 3 are clean before test and

free from hardened concrete and superfluous water .

$. 4ssemble the cube mold correctly and ensure all nuts are tightened.%. 4pply a light coat of proprietary mold oil on the internal faces of the mold.

6. 8lace the mold on level firm ground and fill with sampled concrete to a layer of about %& mm

thick.

. 1ompact the layer of concrete thoroughly by tamping the whole surface area with the ;tandard!amping Bar. /ote that no less than (% tamps ? layer for -%& mm mold and no less than %

tamps ? layer for -&& mm mold3.@. :epeat ;teps % P 6 until the mold is all filled. /ote that ( layers to be proceeded for -%& mm

mold and layers for -&& mm mold3.

F. :emove the surplus concrete after the mold is fully filled and trowel the top surface flush with

the mold.-&. Gark the cube surface with an identification number /say simply -, , (, etc3 with a nail or

match stick and record these numbers in respect with the concrete truck and location of pour

where the sampled concrete is obtained.--. 1over the cube surface with a piece of damp cloth or polythene sheeting and keep the cube in

a place free from vibration for about $ hours to allow initial set .

-. ;trip off the mold pieces in about $ hours after the respective pour is cast. 8ress the concretesurface with the thumb to see any denting to ensure the concrete is sufficiently hardened, or

otherwise demolding has to be delayed for one more day and this occurrence should be stated

clearly in the !est :eport.

-(. Gark the test cube a reference number with waterproof felt pen on the molded side, inrespect with the previous identification number.



-$. 8lace the cube and submerge in a clean water bath or preferably a thermostatically controlled

curing tank until it is delivered to the accredited laboratory for testing.

Chec7ing Qua#it. o& Fine :ggregates an( 3ric7s

Aor checking the quality of fine aggregates, a field test was conducted in which the sand was placed in a flask containing water. !he sand was allowed to settle for some time and then after

few hours the reading of the silt or other impurity layer is taken#f that reading is less than %C of

the total sand that is put in the flask, then we accept the sand but if it is more than %C the sand isrejected. Bricks were sent to the college laboratory for testing and thereby checking the quality

of the bricks used at site.

posted in 8roject :eports N -$ 1omments

Pro6#ems Face( :t Site – Project Report – Mu#tistorie( 3o.s

Boste#PRO31EMS F:CE% :T S9TE

!here were numerous problems which were faced at site. ;ome of these were purely due to thehuman errors and poor workmanship but some were due to unseen factors.

-. !here was a problem in providing beams at one location as per the standard drawings so

the drawings were changed by consulting the structural designers and architect

. !here was problem pouring concrete in one beam due to small area available for pouring

and compacting. !he solution to this problem was that the si"e of steel was increased butthe number of steel bars was decreased so as to provide the total area same.

(. o window was there in staircases which lead to complete darkness, so it was decided to

change the drawing by consulting the concerned authorities.

$. !he depth if beam above the door was (2%5 earlier but to keep the si"e of the door as per the standard it was changed to (2.

%. Arequent power cuts lead to increase in the cost of construction as generators were used

to meet the power requirements

6. 7aying of foundations was postponed by - month due to the rainy season.

. Question ! Te## me a6out .ourse#&

!his is the first question you could be asked in any interview. !his may sound simple but

if you are unprepared you could be in big problem. ;o just prepare yourself for this

simple yet difficult question ;tart with one two lines about yourself, who you are T a brief


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- line about your family U this depends on what kind of interview you are going throughV

and lastly why are you the best suited person for this job. !ell about your achievements

but never sound too proud of your achievements, highlight yourself but with decency.

:emember the golden rule

QAirst #mpression is the last impression.5

@. Question $D What are .our greatest strengthsH

!his question is to judge how you present yourself, are you the person who talks too

much, are you arrogant or are you the one who just do what others say and thus never

reali"ed your strengths.

!he answer to this question should be linked with facts and figures if possible. #f you had

any previous achievements say you lead a team which did wonderful and thus you are a

team leader and all. Highlight yourself, tell your strengths but be sure it is well supported

and you just don2t start sayings just to impress. :emember the H: person will grill you if

he even finds an iota of doubt in what you are saying. ;ome points on which you couldsupport your answer could be < honesty, leadership, tech savvy, confident, good

communication skills, positive attitude, motivational and inspirational leader etc.

F. ;o just prepare yourself for this question, make a mental note of all your achievements.

-&. Question 'D What are .our greatest 8ea7nessesH

ow this is the question which could either end your interview or could just get you the

job. Don2t mince with words, at the same time just don2t be too blunt. !ell your weakness

but also tell what you are doing to over come it. ever say # can not do this. #nstead say, #

have never done this but # am eager to learn and am sure if our company needs it # will doit.

--. ote < ever say your company or what would be my position in your company, use our

company. ;ome H: people might ask you why you are saying our before selection then

do say < its because # am confident that # am the best person for this vacancy.

-. Question ,D Te## me a6out something .ou (i( – or &ai#e( to (o – that .ou no8 &ee# a

#itt#e ashame( o&

!his question is just to see how you react to embarrassing situations. >f course you just

can not say Q;J#8 !H#; 87+4;+.5 ;o better prepare yourself. !ake your time to reply tothis one, at first say # am really finding it very hard to find any such situation as # believe

the best way to avoid shame is never do such things.

-(. Gost of the interviewers just will proceed to another question but if he or she insists to

elaborate then give any appropriate reply but be sure it should not sound that you are so



regretful that it still has a mental impact on you. :emember

57ife must go onW.no matter what5

-$. Question /D Wh. are .ou #ea-ing )or (i( .ou #ea-e" this positionH

By asking this question, the interviewer just wishes to see how much respect you give to

your management, colleagues etc. ;o never say bad words about any of your earlier

employers or management. :emember < ever talk bad about any one even if he or she

has been the worst boss.

-%. !here can be two situation <

Airst is when you already have one job < #n this situation tell truthfully that you see a

bright future or this work profile suits you more than current one or so. ever say < # am

joining you because you pay more. #f you say so, FFC chances are you would be thrown

out of interview.

-6. ;econdly when you are a fresher or you don2t have any job

#f you have been fired, then tell them why you were fired, what you have learnt from that

incident and what are you doing to make sure this would never happen again in life.

Don2t hide the facts, companies do check each and every individual so even if you don2t

tell them, they know it.

-. #f you are a fresher then you just say # am fresher and you are done with this question

-@. Question 0D Wh. shou#( 9 hire .ouH

!he most commonly asked question but the question which is most difficult to answer.

Before you enter any interview make sure you have read about the company, job profile

and all. 4s soon as this question is asked, start matching your personality traits with the

job requirements. ;how how you are the best suited person for this job.

Aor e*ample < #f you are going for a job which involves marketing, then convince the

interview that you have a personality which is best suited for this job.

-F. !he bottom line is < Gatch yourself with what the job profile is and thus the interviewer

should feel that you are the best person for the job.

&. Question 2 D Where (o .ou see .ourse#& &i-e .ears &rom no8H!his question is usually asked to see how much ambitious you are and what is your actual

reason for joining the company. #f you say # see myself as one of the richest manager in

town < forget about the job and leave. Xou need to show that you are a person with

focused aims and you are willing to work to fulfill your dreams. Don2t be over ambitious

and say # want to be in board of directors in ne*t % years. >f course that is not possible

unless lady luck stays with you $' for all % years.



-. During an interview # said < # want to see me at your post and you in top management

and believe me, the interviewer had a very good laugh and said that was really clever. #

don2t suggest you to say this every time but yes if you feel the person has a jolly nature

you can say so

. Question 4D Wh. (o .ou 8ant to 8or7 at our compan.H

(. !his question is asked to check whether you know about the company and work profile

or it was just that you got a call from your friend and you walked in the interview.

;o do your homework and check annual reports of company, browse website or any

relevant data. ;ee the areas where company is growing and match your skills with it.

;how the interviewer how you could add to the overall profit of company.

$. Question 5D What are .our ho66iesH

!his question is asked to judge your personality. # have seen hundreds of resume which

say <

Hobbies < reading books, listening songs, browsing internet , sleeping.

%. Aor god sake don2t copy it from other2s resume and use it. )rite what you actually do.

Don2t write # have a hobby of reading books when you could not even name - book if

asked for. ever be fake, tell them truthfully what you do.

6. Gention some hobbies which are directly or indirectly linked with job. But make sure

you have that hobby. #f not then say what you actually do. Different people have different

hobbies, so there is nothing to be ashamed off

Documents

construction Project Report