Download - Workmanship on Building Sites
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Materials, Handling, PreparationMaterials, Handling, Preparation
SafetySafety
Cement, when mixed with water, releasesCement, when mixed with water, releases
alkali; take precautions to avoid dry cementalkali; take precautions to avoid dry cement
entering the eyes, mouth and nose when mixingentering the eyes, mouth and nose when mixingconcreteconcrete
Prevent skin contact with wet cement orPrevent skin contact with wet cement or
concrete by wearing suitable protective clothingconcrete by wearing suitable protective clothing
If cement or concrete enters the eyes,If cement or concrete enters the eyes,
immediately wash it out thoroughly with cleanimmediately wash it out thoroughly with clean
water, seek medical treatmentwater, seek medical treatment
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ReadyReady--Mix Concrete DeliveryMix Concrete Delivery
Check Delivery TicketCheck Delivery TicketSerial number and date, truck numberSerial number and date, truck number
Name of the Purchaser, Location of the SiteName of the Purchaser, Location of the Site
Grade of Concrete orMix proportion, SpecifiedGrade of Concrete orMix proportion, Specifiedworkability, Min Cement Content, Cement Typeworkability, Min Cement Content, Cement Type
Nominal max size of AggregateNominal max size of Aggregate
Proportion of FlyProportion of Fly--Ash / GGBS in the MixAsh / GGBS in the MixMax Free w/c Ratio, Type of Admixture, dosageMax Free w/c Ratio, Type of Admixture, dosage
Quantity of Concrete, Time of loadingQuantity of Concrete, Time of loading
Any other items specifiedAny other items specified
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Handling and Site StorageHandling and Site Storage
ReinforcementR
einforcementKeep clean; store reinforcement of ground;Keep clean; store reinforcement of ground;cover with polythene sheet to prevent corrosioncover with polythene sheet to prevent corrosion
Do not permit rusting; if necessary cover theDo not permit rusting; if necessary cover the
steel to exclude rain, but allow good circulationsteel to exclude rain, but allow good circulation
of air all around the steelof air all around the steel
Store different sizes separately from each otherStore different sizes separately from each other
and ensure that they are clearlyand ensure that they are clearly labelledlabelled
Dirt / grease prevents proper bond with theDirt / grease prevents proper bond with the
concreteconcrete
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Storing AccessoriesStoring Accessories
Binding wire, joints sealants, water bars, coverBinding wire, joints sealants, water bars, cover
blocks, spaces, admixtures, release agents etcblocks, spaces, admixtures, release agents etc
in conditions and temperatures such that theyin conditions and temperatures such that they
do not deteriorate, becomes damaged, soiled ordo not deteriorate, becomes damaged, soiled orcontaminatedcontaminated
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InIn--Situ ConcreteSitu Concrete
Weather ConditionsWeather ConditionsHot weather: Take precautions to ensure thatHot weather: Take precautions to ensure thatthe temperature of concrete is not higher thanthe temperature of concrete is not higher than
3030oo C at the time of placingC at the time of placing
Cold weather: The temperature of concreteCold weather: The temperature of concreteshould not fall below 5should not fall below 5oo C at any time duringC at any time during
placing and compacting; place the concreteplacing and compacting; place the concrete
quickly; do not place concrete against frozen orquickly; do not place concrete against frozen orice and snow covered surfacesice and snow covered surfaces
Ensure that the concrete temperature is at leastEnsure that the concrete temperature is at least
1010oo C, insulate the concrete surfaceC, insulate the concrete surface
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InIn--Situ ConcreteSitu Concrete
Preparation for ConcretingPreparation for ConcretingClean all rubbish, debris, free water from allClean all rubbish, debris, free water from all
surfaces on to which the concrete is to besurfaces on to which the concrete is to be
poured; remove wire nails, screws etc in thepoured; remove wire nails, screws etc in thecase of formworkcase of formwork
General inspection: Check availability ofGeneral inspection: Check availability of
Materials including RMC, Labor, Plant andMaterials including RMC, Labor, Plant and
Equipment, Power and Water Supply, StandbyEquipment, Power and Water Supply, StandbyEquipment and SparesEquipment and Spares
Confirm setting out checkingConfirm setting out checking
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InIn--Situ ConcreteSitu Concrete
Preparation for ConcretingPreparation for ConcretingConfirm inspection earlier permanent workConfirm inspection earlier permanent work
If appropriate, obtain weather forecastIf appropriate, obtain weather forecast
Check adequacies of access to points ofCheck adequacies of access to points ofdischarge and access platformsdischarge and access platforms
Check readiness of the batching plantCheck readiness of the batching plant
Check the communication systemCheck the communication systemConfirm arrangements for transporting, placing,Confirm arrangements for transporting, placing,
compacting, finishing, curing and testingcompacting, finishing, curing and testing
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InIn--Situ ConcreteSitu Concrete
Preparation for ConcretingPreparation for Concreting--Earth FacesEarth Faces
When concreting against earth surfaces, check:When concreting against earth surfaces, check:
Stability of earth slopesStability of earth slopes
Safety of earth faces when construction plantSafety of earth faces when construction plantis in operationis in operation
Arrangements for removal of waterArrangements for removal of water
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InIn--Situ ConcreteSitu ConcretePreparation for ConcretingPreparation for Concreting--Joints etcJoints etc -- CheckCheck
Construction of joints, dowels, water bars etcConstruction of joints, dowels, water bars etc
Inserts and boxInserts and box--outs for accuracy and securityouts for accuracy and security
Fixing of stop endsFixing of stop endsArrangement for forming kickersArrangement for forming kickers
Preparation of hardened surfacesPreparation of hardened surfaces
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InIn--Situ ConcreteSitu Concrete
Reinforcement CheckR
einforcement CheckSize, type, markings, location and cover areSize, type, markings, location and cover are
correctcorrect
Anchorages and laps are correctAnchorages and laps are correctThat it is rigidly securedThat it is rigidly secured
Surface conditionSurface condition
Use of spacers including type and sizeUse of spacers including type and sizeThe aim of preThe aim of pre--concreting check is to ensureconcreting check is to ensure
that concreting proceeds without delay / defectsthat concreting proceeds without delay / defects
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InIn--Situ ConcreteSitu Concrete
Sampling and TestingSampling and TestingFollow appropriate procedures, usingFollow appropriate procedures, using
equipment in good working orderequipment in good working order
Complete certificates of sampling, cube making,Complete certificates of sampling, cube making,curing and testing to confirm compliance withcuring and testing to confirm compliance with
SpecificationsSpecifications
Transport concrete cubes to the lab ensuringTransport concrete cubes to the lab ensuring
that they are kept moist, are not damaged andthat they are kept moist, are not damaged and
spend the minimum time in transitspend the minimum time in transit
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InIn--Situ ConcreteSitu Concrete
Sampling and TestingSampling and TestingThe procedures for sampling, specimenThe procedures for sampling, specimen
making, curing and testing given in IS:516 &making, curing and testing given in IS:516 &
IS:1199 are very detailed and involve the use ofIS:1199 are very detailed and involve the use of
well maintained standard equipment confirmedwell maintained standard equipment confirmed
at regular intervals to comply with theat regular intervals to comply with the
appropriate Standardsappropriate Standards
Cubes should be stored and tested at anCubes should be stored and tested at anaccredited laboratory; store specimens underaccredited laboratory; store specimens under
controlled temperature (27controlled temperature (27oo C inC in 33oo C)C)
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InIn--Situ ConcreteSitu Concrete
Sampling and TestingSampling and TestingDeviations from standard requirements canDeviations from standard requirements can
affect results significantly and may lead toaffect results significantly and may lead to
errors in judgment concerning the quality of theerrors in judgment concerning the quality of the
concreteconcrete
Supervision of personnel trained in theSupervision of personnel trained in the
procedures is essentialprocedures is essential
The use of a laboratory accredited for siteThe use of a laboratory accredited for site
sampling and specimen making issampling and specimen making is
recommendedrecommended
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InIn--Situ ConcreteSitu Concrete
Placing ConcretePlacing ConcretePlace concrete in one continuous operationPlace concrete in one continuous operation
between and up to the construction joints orbetween and up to the construction joints or
other limiting featuresother limiting features
Discharge concrete through the reinforcementDischarge concrete through the reinforcement
or other obstructions with care; avoid dispersal,or other obstructions with care; avoid dispersal,
segregation or loss of ingredientssegregation or loss of ingredients
Where reinforcement is congested use chutesWhere reinforcement is congested use chutes
or trunking to direct the concrete into positionor trunking to direct the concrete into position
If interrupted, form additional construction jointIf interrupted, form additional construction joint
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InIn--Situ ConcreteSitu Concrete
Displacement while placing ConcreteDisplacement while placing ConcreteWhile placing, ensure no displacement orWhile placing, ensure no displacement or
damage occurs todamage occurs to
damp proof membranesdamp proof membranesreinforcementreinforcement
formwork orformwork or
embedded fittingsembedded fittingsIf displacement occurs, take corrective actionIf displacement occurs, take corrective action
immediately; necessary labor to be availableimmediately; necessary labor to be available
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InIn--Situ ConcreteSitu Concrete
Compacting ConcreteCompacting ConcreteCompact the concrete ensuring thatCompact the concrete ensuring that
a) it forms a solid uniform mass free of voidsa) it forms a solid uniform mass free of voids
b) it is packed tight around the reinforcementb) it is packed tight around the reinforcementc) it fills all parts of formwork or excavationc) it fills all parts of formwork or excavation
d) there is no segregation of ingredientsd) there is no segregation of ingredients
e) it is amalgamated with previous batchese) it is amalgamated with previous batchesf) there is no damage to adjacent concretef) there is no damage to adjacent concrete
g) the required finish will be obtainedg) the required finish will be obtained
h) vibrators are operated by trained personnelh) vibrators are operated by trained personnel
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InIn--Situ ConcreteSitu ConcreteDeep Sections, Walls, Columns, BeamsDeep Sections, Walls, Columns, Beams
Place and compact concrete in layers; eachPlace and compact concrete in layers; each
layer should extend over the length and width oflayer should extend over the length and width of
the section; place succeeding layers withoutthe section; place succeeding layers without
delay and merge them, by compaction, with thedelay and merge them, by compaction, with the
layer belowlayer below
Check for plastic settlement cracking and reCheck for plastic settlement cracking and re--
vibrate as necessaryvibrate as necessary
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InIn--Situ ConcreteSitu Concrete
Surface FinishSurface FinishFill formwork at a steady rate to allow sufficientFill formwork at a steady rate to allow sufficient
time for compaction, but avoid cold jointstime for compaction, but avoid cold joints
between succeeding layersbetween succeeding layers
Do not permit the vibrator to touch any faces ofDo not permit the vibrator to touch any faces of
the formworkthe formwork
Vibrate thoroughlyVibrate thoroughly
Provide uniformed finish as specifiedProvide uniformed finish as specified
Avoid contact between the formwork face andAvoid contact between the formwork face and
the vibratorthe vibrator
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InIn--Situ ConcreteSitu Concrete
CuringCuringCuring period: 7 days for concrete surfacesCuring period: 7 days for concrete surfaces
subject to direct wear or abrasionsubject to direct wear or abrasion
10 days; cure and insulate10 days; cure and insulatesections 300 mm or less in thickness when thesections 300 mm or less in thickness when the
average air temperature is 7average air temperature is 7oo C or lessC or less
Curing compound: A oneCuring compound: A one--time application oftime application of
curing compound at the earliest is deemed tocuring compound at the earliest is deemed to
satisfy the requirements of this clausesatisfy the requirements of this clause
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FormworkFormwork
Fix all props and struts vertically and whereFix all props and struts vertically and where
necessary brace them; provide sole plates andnecessary brace them; provide sole plates and
seat them firmly throughout their lengthseat them firmly throughout their length
Seat all supports adequately and securely onSeat all supports adequately and securely on
their bearingstheir bearings
Fix stop ends securelyFix stop ends securely
Align forms correctly and ensure their levelAlign forms correctly and ensure their level
Reference:Reference: Formwork: Guide to Good PracticeFormwork: Guide to Good Practice
issued by The Concrete Society, UKissued by The Concrete Society, UK
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FormworkFormwork
ConstructionConstruction
Construct formwork to soffits with any preConstruct formwork to soffits with any pre--
camber necessary to allow for deflection of thecamber necessary to allow for deflection of the
formwork; any specified preformwork; any specified pre--camber is forcamber is for
concrete itself. Any preconcrete itself. Any pre--camber to allow forcamber to allow for
deflections of formwork is in addition to thisdeflections of formwork is in addition to this
Construct joints in formwork and betweenConstruct joints in formwork and between
formwork and completed work to prevent loss offormwork and completed work to prevent loss ofgrout. Use foam plastics strip seals, if requiredgrout. Use foam plastics strip seals, if required
Do not overstress the tie boltsDo not overstress the tie bolts
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FormworkFormwork
Cleaning and TreatmentCleaning and Treatment
Before each use of formwork:Before each use of formwork:
a) clean the contact surfaces and dry thema) clean the contact surfaces and dry them
before applying a release agentbefore applying a release agentb) ensure the release agent is appropriateb) ensure the release agent is appropriate
to the surface to be coatedto the surface to be coated
c) coat formwork surfaces evenly and thinlyc) coat formwork surfaces evenly and thinlywith release agent; treat vertical surfaceswith release agent; treat vertical surfaces
before horizontal surfaces and wipe off thebefore horizontal surfaces and wipe off the
excessexcess
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FormworkFormwork Striking TimeStriking Time
Remove the formwork only when the concreteR
emove the formwork only when the concretehas developed sufficient strength; the surface ofhas developed sufficient strength; the surface of
the concrete should not be damaged; thethe concrete should not be damaged; the
structure itself is not overloaded in relation tostructure itself is not overloaded in relation to
the strength reached and there is no excessivethe strength reached and there is no excessivedeflection in structural membersdeflection in structural members
Prop as necessary after striking the formworkProp as necessary after striking the formwork
The concrete strength is assessed by testingThe concrete strength is assessed by testingcubes prepared for the purpose or by referencecubes prepared for the purpose or by reference
to Tables ofMinimum Striking Timesto Tables ofMinimum Striking Times
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FormworkFormwork -- Striking TimesStriking TimesType ofType of
FormworkFormwork
Minimum PeriodMinimum Period
Surface Temp ofSurface Temp ofConc above 16Conc above 16oo CC
before Strikingbefore Striking
Surface Temp ofSurface Temp ofConc 7Conc 7oo CC
Vertical formworkVertical formwork
Columns, Walls,Columns, Walls,BeamsBeams
12 hours12 hours 24 hours24 hours
Soffit formwork toSoffit formwork to
slabsslabs
4 days4 days 6 days6 days
Props to slabsProps to slabs 10 days10 days 15 days15 days
Beams soffitBeams soffit 10 days10 days 15 days15 days
Props to beamsProps to beams 14 days14 days 21 days21 days
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FormworkFormwork
Making good after StrikingMaking good after Striking
Remove fins etc from the surfaceRemove fins etc from the surface
Fill in tie holes with 1:3 semiFill in tie holes with 1:3 semi--dry mortar welldry mortar well
rammed in and finished flush with the face oframmed in and finished flush with the face ofthe concrete; fill blow holes exceeding 5 mmthe concrete; fill blow holes exceeding 5 mm
across with 1:1.5 mortar rubbed inacross with 1:1.5 mortar rubbed in
Take care on permanently exposed concreteTake care on permanently exposed concrete
surfaces; if strength and durability cannot besurfaces; if strength and durability cannot be
assured, agree procedures for repair orassured, agree procedures for repair or
replacementreplacement
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ReinforcementReinforcement
While fixing reinforcement, check the type ofWhile fixing reinforcement, check the type of
steel (Fe 415 / Fe 500) is correct for its locationsteel (Fe 415 / Fe 500) is correct for its location
Steel properties vary, use of lower qualitySteel properties vary, use of lower quality
reinforcement could result in structural failurereinforcement could result in structural failure
Bend reinforcement cold on proper bending m/cBend reinforcement cold on proper bending m/c
Cut and bend bars in accordance with the ISCut and bend bars in accordance with the IS
Do not straighten or reDo not straighten or re--bend bars withoutbend bars without
instructions; if reinforcement temperature isinstructions; if reinforcement temperature isbelow 5below 5oo C obtain instructions before bendingC obtain instructions before bending