ae_-_training_material.doc

8/10/2019 AE_-_training_material.doc

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GUIDELINES GIVEN BY SH.RAMESH JOSHI, GM

HYDERABAD

ABSTRACT:

This program covers different subjects like cracks in concrete, batching, mixing,

placing, compaction and curing of concrete, practice of masonry for stones and concrete

blocks, bituminous road, concrete road, plastering works, water proofing techniques, nondestructive test methods and scaffolding and shuttering in short duration of time. This

report describes most suitable subjects like wpc techniques, cracks in concrete, batching,

mixing, placing, compaction and curing of concrete, for our RM operations.

1. PRODUCTION AND CONTROL OF CONCRETE

BATCHING, MIXING, TRANSPORTING, PLACING,

COMPACTION AND CURING:

A. INTRODUCTION:

oncrete construction methods have changed drastically in our country.

!owadays modern construction equipments are used in all developed countries and in

developing countries. "t is not only essential to concrete with excelle! "#$l%!&but alsonecessary to produce it with '(ee) and ec**+&. "n order to moderni#e and further

develop the construction industry, Re$)& M%x C*ce!e %' $ +#'!.

B. READY MIX CONCRETE:

"f concrete, instead of being batched and mixed at site, is delivered ready forplacing from a central batching plant, it is referred to as READY MIX CONCRETEshortly called as RMC. The Ready Mix oncrete can thus be made under better

conditions of control than are normally done at site mixing. $ince the central mixing

plant operates under near factory condition a really close control of operation is highlypossible. %roper care during transportation of the concrete is also ensured by the use of

agitator trucks. Ready Mix oncrete is well established as technology for many decades

and is used extensively in many countries. &ecause of the cost of the additional elementof transportation Ready Mix oncrete is indeed costlier than site mixed concrete. "f,

inspite of that use of Ready Mix oncrete Technology is so wide spread in manycountries such as '$, '(, )urope, $outh )ast *sia etc., !-e Re$)& M%x C*ce!e %' *!

*l& $ $l#e $))e) (*)#c! /#! $l'* $ 'e%ce $) !-$! %! e'#e' "#$l%!& 0* -%c-

!-e $))%!%*$l c*'! %' +*e !-$ 2#'!%0%e). $ome of the prominent structures in the

world, built using Ready Mix oncrete are+. %etronnas Towers of (uala umpur, Malaysia -The Tallest building in the world

/. 0olden 0ate &ridge, $an 1rancisco, '$*

2. hangi "nternational *irport, $ingapore


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3. $ydney 4pera 5ouse, *ustralia

6. )uro Tunnel -'(71rance

8. The demolished 9orld Trade enter, !ew :ork.

C. BATCHING 3 MIXING:

The principal functional elements of every stationary concrete production plant

comprises of the following.

+. $torage of Materials ; $ilos and 0odown for cement, &ins for aggregates andontainers for admixtures and Tanks for water.

/. &atching arrangement -*utomatic < $emi automatic

2. Measuring and recording equipment3. Mixing equipment

6. ontrol systems

8. )lectrical, hydraulic and pneumatic drives

=. onveying systems -belt 7 screw conveyors

4%5 STORAGE OF CEMENT>

ement is generally stored in $ilos. The procurement and delivery of bulk cement

can be done by ?bulk carriers@. The loading of cement is done with the help of pneumatic

blower system available at plant. "f bagged cement -stored in godown is used then thecement is loaded using a compressed air loader and splitter unit. ement is weighed

separately and is transported from silo into mechanical or electro mechanical weigher by

means of screw conveyor.

4%%5 STORAGE OF 6ATER:

9ater is generally stored in tanks located close to the plant. "t is accuratelymeasured by a water gauge and microprocessor unit.

4%%%5 STORAGE OF AGGREGATE:

The storage of aggregates is done in various ways depends on the type of plant.

a Ve!%c$l P*)#c!%* Pl$!: "n this plant the aggregates are stored above the

batching and mixing elements in one or more silos. *s the aggregates are stored in

silos it is relatively easy to protect the aggregates from very low temp. in winter

period.b H*%7*!$l P*)#c!%* Pl$!:

%5 S!$ P$!!e A88e8$!e S!*$8e> 5ere the aggregates can be stored exposed toambient temperature in different compartments forming a star type pattern. 4ur

N$c-$$+ (l$!belongs to this type.


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%%5 Il%e A88e8$!e S!*$8e S%l*': The inline aggregate storage silo system

continuously requires a shovel wheeled loader to charge the silo with fresh materials. Theaggregates are weighed on an electro mechanical weigher belt. 4ur M%&$(# (l$!belongs to this type.

D. MIXING ARRANGEMENTS:

oncrete mixing is normally done by mechanical means but some site mixing ofconcrete is done by hand for small structures. The object of mixing is to coat the surface

of all aggregate particles with cement paste to blend all the ingredients of concrete into a

uniform mass. %an type and twin shaft power mixers have shorter mixing time give better

homogeneity, consistency and strength to the concrete.4ur N$c-$$+ (l$! has ($ !&(e mixer and M%&$(# (l$! has !% '-$0!

power mixer for giving high homogeneity and uniformity of concrete.

CONTROL SYSTEM:

1ully automatic plant control systems even up to +6AA mixes of different typescan be stored along with names and addresses of the consumer. The mix data with

quantity can be printed by the printer if required by the customer. *part from this,

moisture recorder and mixer mind for consistency of mix also provided.

15 MOISTURE RECORDER:

These recorders actually measure the moisture present in sand. * recording unit,which calculates the average moisture value of the sand, passes on the information to the

batching control unit to allow corrective action to be taken.

95 CONSISTENCY OF MIX:

onsistency of the concrete mixes checked by remote recording system whichautomatic, easy and accurate. "f concrete is very dry or stiff the electrical resistance of the

batch is measured and if the concrete is wet the motor output is measured. $o one

*(e$!*is more efficient, he need not require a chemist to check the slump of concrete

in e$c- $) ee& e-%cle. 5e can maintain the consistency of the mix once the initialrequirement slump is correlated with motor out put.

T-e'e $e e"#%e) 0* /e!!e "#$l%!& c*!*l, -%8-e ec**+& $) '#(e%*

*%8 c*)%!%*'.

E. TRANSPORTATION:

oncrete shall be transported from the mixer to the formwork as rapidly as

possible by methods, which will prevent the segregation or loss of any of the ingredients

and maintaining workability. The modes of transportation are as follows.


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+ 5ead loads 7 human chain

/ ranes2 &uckets

3 9heel borrows

6 hutes8 &elt conveyors

= Tippers

B Transit MixersC oncrete pumps etc.,

The most common observation at '%!e +%x c*ce!e 4SMC5is a combination of manual

and mechanical mode of transportation is used. T-%' )*e' *! 8%e !-e "#$l%!&,

e00%c%ec& $) (e0*+$ce ex(ec!e) *#! *0 0#ll& +ec-$%c$l +*)e *0

!$'(*!$!%*.

1rom the various methods used, !#c +%xe' with different load carrying capacity are

found to be most suitable for transporting concrete mix in hori#ontal direction -footing,

foundation, walls, slabs on ground and c*ce!e (#+(' with different pumpingcapacityare found suitable for transportation of mix in both hori#ontal and vertical direction. "t is

therefore, desirable to go for total mechani#ation as far as possible for effective mode oftransporting concrete without affecting its quality, for this purpose the need of SMC !*

RMCis very much essential. $o it our duty to create awareness among the customer to

go for RM from $M irrespective of cost difference.

T$'%! M%xe': The capacity of transit mixers ranges from / to +/ cubic meters. 8 cu.m.

capacity being ideal. The transit mixers in which the concrete inside the drum revolves

slowly so as to prevent segregation and undue stiffening of the mix. The speed of rotationof drum may vary between 3 to +8 rpm.

F. PUMPING OF CONCRETE>

"n the past fifty years, the pumping of concrete has established itself an e00%c%e!and ec**+%c$l mode of transporting concrete over long distances and significantheights. "ts use has become widespread in the building and construction industries.

4%5 P%c%(le *0 (#+(%8 c*ce!e:

%umping concrete is a concrete, which has been conveyed by pressure through

rigid pipeline with flexible end hose discharged directly to a desired location, which may

be its final location.

4%%5 T&(e' *0 (#+(':

4rdinary mobile pump, truck mounted pump and truck mounted boom pump.


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%ipe diameter -mm Mass of 2 meter empty pipe -kg

+AA 2A+/6 3A

+6A 66

$o one workman can handle and easily shift pipe -+AAmm dia from one end to anotherend of slab. *ccording to *merican concrete pumping association, the dia of pipeline

should be 3 times greater than the of maximum si#e aggregate to avoid choking. 1or

/Amm aggregate, the minimum dia of pipeline should be BAmm.

Maximum si#e aggregate Fia of pipeline

/6 mm G 2=mm +/6 mm +C mm G /6 mm +AA mm

H+C mm =6 mm

*t present we are using +/6mm diameter pipeline for pumping concrete with /Ammmaximum si#e aggregate.

Be)': &ends in pipeline are used to reduce the effective pumping distance. !ormally

CAA, 36A, and //.6A bends are available. They can be called as IJ bend or I$J bends

depends upon its shape.

Fegree of bend Reducing pipeline distance

//.6A 2 meter36o 6 meter

CAA +A meter

4%5 P#+( Leel%8 $) P%(el%e L$&%8>

+ The area needed for pump leveling should be carefully selected so as to allow

easy discharge of concrete from the transit mixer.

/ )fficient pump operation will normally achieved by keeping the pipeline to the

point of delivery as short as possible and minimi#ing the number of bends andcoupling involved.

2 %ipes should be laid either hori#ontally or vertically and should be firmly

anchored, particularly at bends.3 are should be taken the load of pipelines do not affect the position of formwork

or reinforcement

6 %rior to its arrival on site, the pipeline including all fittings should be clean and ingood condition. 'nclean pipelines may induce chocking.

8 The wear and tear of pipe wall thickness should be checked at regular intervals of

time.


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= 1or laying pipeline for multi storeyed building for example 6thfloor and above,

the minimum distance between pump and vertical pipeline should be 6meter to

avoid choking in the pipeline.B C*ec!%8 (%(e> "t is highly useful for connecting pipelines from different

manufacturer like stetter and put#miet#er for longer distances like +AA meter and

above.

4%%5 P%+%8 * L#/%c$!%8 *0 (%(l%e' /e0*e c*ce!e )%'c-$8e:

"mmediately prior to the discharge of the first load of concrete into pump hopper

the pump and pipeline should be primed or lubricated with a cementitious mortar in order

to prevent the loss of lubricating fluid from the concrete. * lubricating mix is then

pumped into the line to coat the inside area of pipe and followed by the concrete to bepumped.

4%%%5 L#/%c$!%8 M%x * 'l#& (e($$!%*:

The lubricating mix or priming mixture consists of two parts by volume of river

sand to one part of cement and sufficient water to give a flowable consistency. Thequantity of lubricating mixture is dependent on the diameter of the pipeline and its length.

"n general 6A to +AA litres of priming mixture is required for the pipeline less than 6A

meters length. *fter lubricating pump and pipeline, the pump is ready to deliver theconcrete over the slab.

4%x5 C$#'e' 0* P%(el%e C-*%8:

The following are few reasons for inducing pipeline choking or blockage.

+. Sl#& Le$$8e> The pump operator should ensure that there is no leakage ofslurry in pipeline joints especially in the initial segments. 9hen this leakage of

slurry occurs, the lubricating layer is lost, the coarser particles interlock, the

friction between the aggregate particles and the pipeline increases. Therefore theconcrete stops moving in the pipeline. This is called as ;C-*%8


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+3. 5oles made in the formwork on site should be neatly plugged, otherwise leakage

of slurry will be observed.

+6. The props should have a firm bearing. "f supporting base is weak in takingbearing pressures alternative arrangements like spreaders should be used.

H. COMPACTION OF CONCRETE:

oncrete should be thoroughly compacted and fully worked around the

reinforcement, around embedded fixtures and into corners of the formwork by means ofcompaction. ompaction can be done by mechanical vibrators. 1or mos of the placing

conditions, internal vibrators -needle vibrators are suitable. The diameter of the needle

shall be determined based on the spacing of reinforcement bars and thickness sections.

The following care should be taken during compaction of concrete.

+ Librators transmitted to the formwork can be considerable resulting in loosening

of wedges and fixings. *ll fastenings, bolts should be continuously observed and

tightened whenever necessary./ Libration should be *(!%+#+. 4ver vibration resulting in settlement of aggregate

particles at the bottom leaving slurry on top surface of concrete. This may inducedevelopment of plastic shrinkage or settlement cracks.

2 "f vibration is not sufficient, which will lead to development of honeycombed and

porous concrete. Fue to this moisture may penetrate into concrete and corrodesteel causing durability problems.

3 Furing compaction, insert vibrator vertically into concrete allowing it to

penetrate rapidly to the bottom for 6 to +6 seconds depending upon workability

of concrete.6 FonJt use a vibrator to move concrete hori#ontally.

8 FonJt push or force a vibrator into concrete, it may get caught in the

reinforcement.= The distance between successive positions of the vibrator must not exceed one

and a half times its radius of operation.

B $top vibrating concrete when large air bubbles no longer escape.C FonJt let a vibrator run very long outside concrete, it will over heat also

consumption of fuel will increase.

+A Libration should not be used for spreading concrete heap in forms.

++ ast but not least donJt start concreting work without a spare vibrator.

I. CURING OF CONCRETE:

+ MOIST CURING> )xposed surfaces of concrete shall be kept continuously in a

damp or wet condition by ponding or by covering with a layer of sacking, canvas,

hessian or similar materials and kept constantly wet for atleast seven to ten days fromthe date of placing of concrete. 9henever wind velocity and temperature of

atmosphere is high, the slab should be cured as early as possible in order to avoid

rapid rate of evaporation of water on top surface thereby minimi#ing plastic

shrinkage cracks. The following moist curing methods are commonly used at sites.


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P*)%8> This is most common method of curing concrete slab and pavements. "t

consisting of storing the water to a depth of 6Amm on the concrete surface. C*e%8 !-e c*ce!e %!- e! /#l$(> The concrete is covered with burlap -Kute

as soon as possible after placing. The material is kept continuously moist for the

curing period.

S(%l%8 *0 $!e> The sprinkling of water can be one in fine streams throughno##les fixed to a pipe.

/ MEMBRANE CURING> *pproved curing compounds may be used in lieu of moist

curing. $uch compounds can be applied to all exposed surfaces of the concrete assoon as possible after the concrete has set.

;Receiving of good quality of raw material and proper design mix and strict qualitycontrol tests on fresh concrete alone c$*!ensure good concrete. This is 4.(. up to

production and despatching of fresh concrete from plant. "t is often necessary to ensure

the concrete dispatched from plant is properly placed, compacted and cured through 8**)

*+$'-%(.

)ntire quality control tests, proper design mix with good quality raw material will be#'ele'' once the concrete is placed with (** *+$'-%( and /$) c*'!#c!%*

($c!%ce.@*lso it is very difficult and costly to alter concrete once it is placed. 5ence

constant and strict supervision of '%!e % c-$8e and A((l%c$!%* E8%ee is very

important at site when concreting is going on.

J. REMOVAL OF FORM6OR?:

1orms may generally be removed after the expiry of following period.

T&(e *0 0*+* M%%+#+ (e%*) /e0*e '!%%8 0*+*

Lertical formwork to columns +8 to /3 hours

9alls, large beams

1ormwork to slabs 2 days

-props to be refixed immediately

after the removal of formwork

1ormwork to beams = days

%rops to slabs+ $panning upto 3.6 meter = days

/ $panning over 3.6 meter +3 days

%rops to beams and arches

+ $panning upto 8 meter +3 days

/ $panning over 8 meter /+ days


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9. CRAC?S IN CONCRETE

racking of concrete is a complex phenomenon. *ll the concrete structures crack

in some form or other. racking of concrete structures can never be totally eliminated.

The development of cracks and their repair including considerable cost andinconvenience to the builders. *dopting good construction techniques can prevent it. "n

general concrete cracks when increase of tensile strain beyond the tensile strain capacity

of concrete. racks are broadly classified into two types.

+. S!#c!#$l C$c'> Fue to incorrect design, overloads, faulty construction.

/. N*@'!#c!#$l c$c'> Fue to internally induced stress in building materials.

racks are generally observed in two forms>

I @ C$c' /e0*e -$)e%8 *0 c*ce!e: This is may due to

i. %lastic shrinkage cracks

ii. %lastic settlement cracksiii. 1ormwork movement.

II @ C$c' $0!e -$)e%8 *0 c*ce!e> This may due to

i. Frying shrinkage

ii. orrosion of reinforcementiii. *lkali silica reaction

iv. ement carbonation

v. 1ree#e thaw cyclevi. Fesign load

vii. )arly thermal contractions

viii. )xternal seasonal temperature variations.

%5 Pl$'!%c '-%$8e c$c'>

These cracks occur in concrete before it hardened in a period of + to B hours. 4vervibration < bleeding influences plastic shrinkage cracks.

Pee!%*> + using windbreakers / %lastic sheets to cover the top surface of concrete

to avoid rapid rate of evaporation of water 2 )arly curing 3 'sing low w7c ratio mixes6 optimum vibration.


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%%5 Pl$'!%c 'e!!le+e! c$c':

This type of cracks is formed directly over the formwork tie bolts or

reinforcement near the top. This may due to high slump, bleeding and rapid drying of

concrete on top surface.

Pee!%*: + Revibration can be done / ow slump concrete with sufficient vibration.

2 )arly curing.

Re+e)&: The remedial measures for the above plastic shrinkage and plastic settlement

cracks after the concrete has hardened is sealing the cracks in order to (*!ec!

e%0*ce+e!. The sealing can be done by using cement mortar or low viscositypolymer.

%%%5 D&%8 '-%$8e c$c':

?"t develops only if there is a restraint@. Frying shrinkage is reduction of volume

of concrete caused by chemical < physical loss of water during hardening process. * lossof moisture from concrete paste results volume shrinkage by as much as one percent. The

surface cracking on slabs and walls usually occurs due to drying shrinkage. The extent of

this type cracks depend upon the amount of shrinkage.

Pee!%*: 0enerally this type of shrinkage cracks decrease with the increase in the

amount of aggregate and the reduction in water content. Therefore using the maximum

practical amount of aggregate and lowest usable water content in the mix can reduce thedrying shrinkage. *dequate curing up to a minimum period of = to +A days is essential.

%5 T-e+$l C$c':

The temperature difference within a concrete structure result in differential

volume change. rack caused due to heating of concrete due to hydration in first /3 hoursand then cooling at later stage of hydration. This will create internal and external restrain.

0enerally it is observed in high thick section slab, very rich mixes -high grade concrete

mixes and mass concrete works. !ormally it will appear several weeks after placement

of concrete.

Pee!%*: + Reduce heat of hydration using blended cement. / Reduce initial

temperature of material by sprinkling water 2 Temperature of surrounding -!ormallymass concrete works like large footings, foundation will start in the evening about 3.AA

p.m. 3 )arly curing and constant curing will protect concrete from rapid drying and

cooling.


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45 C$c%8 )#e !* c**'%* *0 e%0*ce+e!:

"t is the most frequent cause of damage to reinforced concrete structures. The

corrosion of steel provides iron oxides and hydroxides, which have a volume much

greater than the volume of original metallic iron. This increase in volume causes radialcracks around reinforcing bars. The splitting cracks may propagate along the bars

resulting in the formation of longitudinal cracks parallel to the bar.

Pee!%*: + oncrete with low permeability ie low w7c ratio / $ufficient cover

thickness 2 hemical coated reinforcement 3 orrosion G inhibiting admixtures can be

used.

4%5 C$c%8 )#e !* $l$l% '%l%c$ e$c!%*:

The concrete may crack due to local expansion as a result of reactions between

aggregate containing reactive silica and alkalis from cement hydration.

Pee!%*: + %roper selection of aggregate / 'se of low alkali cement 2 'se ofblended cement

The cracks due to corrosion of reinforcement and alkali reaction will appear on surfaceonly /;2 years after placing concrete.

4%%5 C$c%8 )#e !* (** c*'!#c!%* ($c!%ce':

%oor construction practices such as adding plenty of water to concrete to improve

workability, lack of early curing, inadequate form support, inadequate compaction can

result in cracking in concrete structures.

There are so many reasons behind formation of cracks on slab. $o, in order to get )e0ec!0eeslab the following simple principle should be used.

+. Rigid < tight formwork.

/. oncrete with proper design and good quality raw material

2. ow water cement ratio3. Maximum slump of CA to +AA mm when placing concrete.

6. 4ptimum vibration.

8. )arly curing and minimum continuous curing up to = to +A days from the date ofplacement of concrete.

=. 0ood workmanship.


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=. CONCRETE 6ITH 6ATER PROOFING COMPOUND

NEED FOR 6PC:

"f concrete having voids and capillaries due to improper grading of material and

water entrapment - due to high water cement ratio, the water will penetrate into concrete

body, corroding reinforcement and causing durability problem. $o the materials used toreduce flow of water inside the concrete body are called as 9ater %roofing ompounds.

(indly note that ? A c*ce!e -$%8 (*(e +%x )e'%8, l* $!e ce+e! $!%* $)

'*#) $88e8$!e %ll /e %+(e+e$/le $) ee) * $!e (**0%8 $))%!%e'. "ntegral water proofing liquid admixtures directly

added to concrete mixers to render the concrete watertight. The chemicals contained inthe formulations react with water and other elements in concrete to form crystal, whichpenetrates the concrete, and fill pores and capillaries. The crystals block the passage of

water and become an integral part of concrete. *t M%&$(#and N$c-$$+plant integral

water proofing compound is being used as per c#'!*+e e"#e'!.

*part from above method, polymer modified cementitious coatings, polyurethane

and epoxy coatings and polymer modified bituminous membranes water proofingsystems are available for roof structures.


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. ADVANTAGES OF READY MIX CONCRETE:

+. UALITY CONTROL 3 UALITY ASSURANCE: The ee and /$% of

RM plant is the quality control laboratory equipped with sophisticated instruments

and manned by trained and experienced personnel. The quality is monitored at every

stage, right from receipt of the raw material to dispatch and placing of concrete,which ensures that consistent quality, reaches the customer. The following tests are

conducted for quality assurance.

%5 Ce+e!: !ormal consistency, "$T, 1$T, ompressive strength,hemical analysis as per manufacturerJs certificate.

%%5 F%e A88e8$!e: $ieve analysis -daily basis, silt test -daily basis

specific gravity, density moisture content -daily basis, waterabsorption

%%%5 C*$'e A88e8$!e: $ieve analysis -daily basis, impact value, density

-once in a week, dust percentage -daily basis%5 6$!e: hemical analysis as per "$ 368;/AAA requirements.

5 C*ce!e: 9orkability, :ield, Fensity, and compressive strength.

%5 C#'!*+e Se%ce: The following technical services are also offered

by the RM plant 15 C*+(e''%e '!e8!- !e'! ce!%0%c$!e' 95

Tec-%c$l $''%'!$ce 0* c#'!*+e % c*'!#c!%* $'(ec!' '(ec%$ll&

-e #'%8 RMC.

"n RM, the concrete is delivered with required consistency, quantity, andcompressive strength. $o, in RM the concrete is delivered with a quality assurance.

This type of "#$l%!& $''#$ce c$*! /e $c-%ee) % '%!e +%x c*ce!e.

/. CORRECT ACCOUNTABILITY OF INGREDIENTS: The mixes in RM arepre;determined, hence the consumption of all the ingredients used for making the

dayJs total concrete production can be correctly known, recorded and accounted for.

T-e $%$!%* % $ +$!e%$l c*'#+(!%* % SMC %' +*e.

2. AVOIDANCE OF GODO6NS FOR STORAGE OF MATERIALS: The

customers and project owners are relieved of providing a godown for storage ofmaterials and the supervisory staff and related expenses otherwise needed for site mix

concrete activity.

3. ECONOMIC MIXES: "n RM the concrete is provided on weight basis where as in

site mix concrete the concrete, the concrete is produced on volume basis. $o thewastage of cement content due to volume batching cannot be avoided at site.

Moreover accurate blended and economic mixes are not possible using po##olanicmaterial at site mix concrete.

6. PRODUCTION OF HIGHER GRADE CONCRETE: The RM can producehigher grade concrete varying from M6A to M=6 without hassles. The concrete could


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also be made using different types of cements vi#. 62 grade, 32 grade, %%, slag

cement, $R etc., as there will be 2 silos for storage of different types of cement.

8. MEGA PROJECTS DEMAND HIGHER OUTPUTS: The nature of mega

construction projects and its expected output of concrete per day is high. Many

industrial and commercial structures have to be completed as a time boundcommitment. This calls for huge production and handling of concrete at a much faster

pace. Ready Mix oncrete with an output of 8A G BA cu.m. per hour is the only

answer to meet these challenging demands of the construction industry.

=. TIMELY DELIVERY 3 SAVINGS IN LABOUR COST TO THE CUSTOMER:9ith the help of transit mixers and high capacity pumps, it is possible to deliver huge

quantity of concrete in record time, thereby lot of labour cost can be saved to thecustomer. 9hereas it is not so for the site mixed concrete having smaller capacity of

concrete mixers.

B. EASY ORDER BOO?ING: 4rdering the concrete will normally be theresponsibility of the contractor or customer to contact marketing department of RM

supplier. 4nce the order is placed, the RM supplier will dispatch the concreteaccording to the requirement. 4therwise2#'!*e (-*e c$ll %' '#00%c%e!in one;hour

advance to the supplier to dispatch required quantity of concrete at right time. The

following essential information to be given to RM supplier by the contractor>

ontractorJs !ame

%roject name and address with phone number

Fate and time of concrete required

0rade of concrete

Total quantity required The type of pump -&oom or line pump and number of pumps for pumping

concrete *ny specified mix required with any additives like 1ibres, 9% and extra cement

content

uality requirements like maximum slump at site, early age strength, maximum

si#e aggregate etc., Testing requirements like slump test, no. of cubes cast at site if any.

CONCLUSION:

The future of RM in "ndia is bright. The allotment of land at concessional rates

and availability of water, electricity and other infrastructure and removal of sales tax bystate government would accelerate the growth of RM industry in "ndia. I! %'

ec**+%c$ll& %$/le !* 'e! #( $ Re$)& M%x C*ce!e (l$! -%c- %ll ($& /$c !-e

%e'!+e! % $/*#! =@ &e$' )e(e)%8 %!' *l#+e *0 (*)#c!%*. Many governmentdepartments like Railways, %ort trust, 5igh ways, %9F, *irport *uthority of "ndia and


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flat promoters7builders are likely to use RM for their future projects thus creating a

bright future for RM industry for faster track and quality construction.

. COMPARISON OF SMC AND RMC

Sl.*. De'c%(!%* SMC RMC

+ Raw material required near mixer &atching plant

/. &atching Lolume batching weight batching

2. 97 ratio Manual not accurate *ccurate

3. *dmixture Manual omputerised

6. Mixing Tilting mixer Turbo Mixers

8. Mixing time *pproximate *uto timer

=. &atch si#e +3A litres /AAA litres

B. Fischarge platform Truck mixer

C. Rate of production 2 cu.m.7hr. 6A cu.m.7hr.

+A. Fegree of control 1air Lery good

++. :ield Lariable onsistent

+/. Testing of fresh concrete once in /6 batches &atch to batch

+2. Mode of placing Manual7hoist7crane TM < pumps

+3. Time frame +AA cu.m.7day +AAA cu.m.7 day

+6. abours requirement More ess

+8. uality Lariable

onsistent

+=. Technical service "t depends on Masons %rovided by

wellexperienced

and qualified

personnel

+B. ost per cu.m. low high


18/18

CONTENTS:

15 PRODUCTION AND CONTROL OF CONCRETE

A. INTRODUCTION

B. READY MIX CONCRTE

C. BATCHING

D. MIXING AND CONTROL SYSTEM

E. TRANSPORTING OF CONCRETE

F. PLACING OF CONCRETE

G. COMPACTION OF CONCRETE

H. CURING OF CONCRETE

95 CRAC?S IN CONCRETE

=5 CONCRETE 6ITH 6ATER PROOFING COMPOUND

5 ADVANTAGES OF RMC

5 COMPARISON OF SMC AND RMC

ae_-_training_material.doc

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