Ready Mixed Concrete.pdf

In this Slides definition,types and manufacturing of Ready Mixed Concrete(RMC) has been discussed. This will be of great help to the students of civil engineering. They will find it more handy and easily understandable. This will also help to Teachers and professionals.

1. Ready Mixed Concrete
Prepared By
Gourhari Biswas,

2. Ready MixedConcrete (RMC)
•ReadyMixedConcreteisatailor–made
concretethatismanufacturedinafactory
orwithinabatchingplantbasedonthe
standardrequiredspecifications.The
preparedconcretemixisthentakentothe
worksitewithintransitmixersmounted
overatruck.
•Readymixedreferstoconcretethatis
batchedfordeliveryfromacentralplant
insteadofbeingmixedonthejobsite.

3. Uses of Ready Mixed Concrete
•Itisusedintheconstructionofbridge,dametc.
•Itisusedintheconstructionoverheadroads,
pools,multi-storiedbuildingetc.
•Itcanbedirectlyusedattheconstructionsite.
•Ithelpgreaterelementofautomationand
precisionconcretemixing.
•Amuchhigherqualityandmoreconstituent
uniformityandincreasestandardizationand
speedwhichisdonetentimesfasteras
comparedtositemixedconcrete.

4. Advantages of Ready Mixed Concrete
•Qualityconcreteisobtainedasaready-mixconcretemix
plantmakeuseofsophisticatedequipmentand
consistentmethods.Thereisstrictcontroloverthe
testingofmaterials,processparametersandcontinuous
monitoringofkeypracticesduringthemanufacture.Poor
controlontheinputmaterials,batchingandmixing
methodsinthecaseofsitemixconcreteissolvedina
ready-mixconcretemethod.
•Speedintheconstructionpracticesfollowedinreadymix
concreteplantisfollowedcontinuouslybyhaving
mechanisedoperations.Theoutputobtainedfromasite
mixconcreteplantusinga8/12mixeris4to5metric
cubesperhourwhichis30-60metriccubesperhourina
readymixconcreteplant.

5. Advantages of Ready Mixed Concretecontd...
•Betterhandlingandpropermixingpracticewillhelpto
reducetheconsumptionofcementby10–12%.Useof
admixturesandothercementitiousmaterialswillhelpto
reducetheamountofcement.
•Theconcretemixedisusedwithhighversatility.Itis
placedbyfollowingbestconcreteplacingmethods.
•Cementissavedandthedustcausedisreducedas
readymixconcretemakeuseofbulkconcreteinsteadof
bagsofcement.
•Cementsavingwillconservetheenergyandthe
resources.
•Lessconsumptionresultinlessproductionofcement
hencelessenvironmentalpollution.
•Moredurablestructureisobtainedthusincreasingthe
servicelifeandsavingthelifecyclecosts.

6. contd...
•Readymixconcretemanufacturehavelessdependency
onhumanlabourshencethechancesofhumanerrorsis
reduced.Thiswillalsoreducethedependencyon
intensivelabours.
•Smallorlargequantitiesofconcreteasperthe
specificationisdeliveredtimelyatthesite.
•Thisdemandsnospaceforstoringtherawmaterialsat
site.Thereisnodelayduetositebasedbatchingplant
erection/dismantling;noequipmenttohire;no
depreciationofcosts.
•Petrolanddieselconsumedislessthusnoiseandair
pollutionisreduced.
•Betterqualityconcreteisproducedasitismadefrom
consistentmethodsandinadvancedequipment.

7. Advantages of Ready Mixed Concretecontd...
•

8. Disadvantages of Ready Mixed Concrete
The transit time from the time of preparation of concrete
to the delivery site, will result in loss of workability. This
will demand for additional water or admixtures to
maintain the workability as per the specification.
Traffic during the transit of concrete can result in setting
of concrete. This will hence require addition of
admixtures to delay the setting period. But unexpected
traffic is a great problem
Requires hugeinitial investment.
Not suitable for small projects (less quantity of concrete
is required).
Need aneffective transportation systemfrom the
batching plant to the job site.

9. Types of Ready-Mix-Concrete
There are three
types in ready-mix
concrete:
Transit mixed
concrete
Shrink-mixed
concrete
Central-mixed
concrete

10. Transit mixed concrete
•Itisalsoknownastruck
mixedconcrete,inwhich
materialsarebatchedata
centralplantandare
thoroughlymixedinthe
truckintransition.
•Transit-mixingavoidsthe
problemsofearlyhardening
andslumplossthatresultin
delaysintransportation.

11. Shrink-mixed concrete
Inthistype,concreteis
partiallymixedinastationary
mixeratthereadymixplant.
Thefinalmixingisdoneina
truckmixerenroutetothejob.
Itisusedtoincreasethetruck's
loadcapacitywhereconcreteis
mixedattheplanttoshrinkthe
volumeoftheconcrete.
Thebalancemixingofconcrete
iscompletedinthetruckduring
transittimeoratthe
constructionsite.

12. Central-mixed concrete
•Sometimes,thecentralmixed
plantsarereferredtoaswet
batchplants.Theconcreteis
batchedandcompletely
mixedinastationarymixerat
theplantsitebefore
dischargingitintothetruck
mixers.
•Theadvantagesofcentral-
mixedconcretearebetter
qualitycontrol,consistency,
higherproductioncapability
andreducewearonthetruck
mixerdrums.
Stationery Batching
Plant

13. Batching and Mixing of Ready Mixed Concrete
Stationary Mixing of
Concrete
StationaryMixersareusedonsiteor
CentralMixR/Mplant.Itisusedfor
completeorshrinkmixing.The
concretemixercanmixupto9m3.
Itcanhavetiltingornon-tiltingdrum,
opentoprevolvingbladeorpaddle.
Typicalcompletemixingtimesof
thismachineisminimumof1min.
forupto1m3orlessmixercapacity
plus15secondsforeachadditional
m3orfractionthereof.
Control room for batching
equipment

14. Truck Mixed Concrete
Truck Mixed
Concrete
Itrequires70to100
revolutionsrequiredfor
mixing.Mixingspeedvaries
from6to18rpm.After
mixing,drumrevolvesat
agitatingspeed,2to6rpm.
Theconcreteneedstobe
discharged before
exceeding 300 drum
revolutionsandbefore1½
hours.

15. Transporting and Handling of Ready Mixed
Concrete
Wheelbarrows and
Buggies
Theseareusedfor
shortflathaulsonall
typesofonsiteconcrete
construction. its
advantages:Versatile—
idealinsideandon
jobsiteswithchanging
placingconditions.This
methodisslowand
laborintensive.

16. Belt Conveyor
Itisusedforconveying
concretehorizontallyor
higher/lower level.
Advantages: Adjustable
reach,travelingdiverter,
variablespeed.End-
dischargearrangements
needed to prevent
segregationandmortaron
returnbelt.Beltcover
neededinhotand
windyweather.

17. Truck Mounted Conveyors
Itisusedforconveying
concretehorizontallyor
higher/lower level.
Advantages:Conveyer
arriveswithconcrete.
Adjustablereachand
variablespeed.Watchfor:
End-discharge
arrangementsneededto
preventsegregationand
mortaronreturnbelt.Belt
coverneededinhotand
windyweather.

18. Buckets
I

19. Cranes and Buckets
Itisusedforwork
abovegroundlevel.
Itsadvantages:Can
handle concrete,
reinforcingsteel,
formwork, and
sundryitems.

20. Pump
Pumpsareusedforconveying
concrete from central
dischargepointtoformwork.
Itsadvantages:Pipelinestake
uplittlespaceandcanbe
readilyextended.Delivers
concreteincontinuousstream.
Pumpcanmove.Watchfor:
Constantsupplyoffreshly-
mixedconcreteisneeded
withoutanytendencyto
segregate.

21. What is Concrete Pump?
AConcretePumptruckisatool
thatisusedforconveyingor
carryingthefreshlymixed
liquidconcretefromthe
containersorthebatching
plantstotheconstructionsites
whereitneedstobecastedor
filled.
Aconcretepumpisavery
importanttoolforthebig
constructionprojects for
conveyingorcarryingliquid
concreteandbecameamost
common equipment in
everyconstructionsites.