Concrete Mix Design.pdf

Cocrete mix design

1. Concrete Mix Design
Unit-III

2. Syllabus
ConcreteMixDesign
•MixDesignforcompressivestrengthbyI.S.Method,Road
NoteMethod,Britishmethod,MixDesignforflexural
Strength

3. Concrete Mix Design
•Concretemixdesignmaybedefinesastheartofselecting
suitableingredientsofconcreteanddeterminingtheir
relativeproportionswiththeobjectofproducingconcreteof
certainminimumstrength&durabilityaseconomicallyas
possible.

4. Objectives of Mix Design
•Thepurposeofconcretemixdesignistoensurethemostoptimum
proportionsoftheconstituentmaterialstofulfilltherequirementof
thestructurebeingbuilt.Mixdesignshouldensurefollowing
objectives.
•Toachievethedesigned/desiredworkabilityintheplasticstage
•Toachievethedesiredminimumstrengthinthehardenedstage
•Toachievethedesireddurabilityinthegivenenvironment
conditions
•Toproduceconcreteaseconomicallyaspossible.

5. Basic Considerations
•Thefollowingpointmustbeconsideredwhiledesigningconcrete
mixes
•Cost
•Specification
•Workability
•StrengthandDurability

6. Basic Considerations
Cost
•Thecostofconcreteismadeupof
•MaterialCost
•EquipmentCost
•LabourCost
•Thevariationinthecostofmaterialsarisesfromthefactthatcementis
severaltimescostlierthanaggregates.Soitisnaturalinmixdesigntoaim
atasleanamixaspossible.Therefore,allpossiblestepsshouldbetakento
reducethecementcontentofaconcretemixtureswithoutsacrificingthe
desirablepropertiesofconcretesuchasstrengthanddurability.

7. Basic Considerations
Specifications
•Thefollowingpointmaybekeptinmindwhiledesigningconcrete
mixes
•MinimumCompressiveStrengthrequired
•Minimumwater/cementratio
•Maximumcementcontenttoavoidshrinkagecracks
•Maximumaggregate/cementratio
•Maximumdensityofconcreteincaseofgravitydams

8. Basic Considerations

9. Basic Considerations
Workability
•Thefollowingpointsrelatedtoworkabilityshallbekeptinmindwhile
designingconcretemixes.
•Theconsistencyofconcreteshouldnomorethanthatnecessaryfor
placing,compactingandfinishing.
•Forconcretemixesrequiredhighconsistencyatthetimeofplacing,the
useofwater-reducingandset-retardingadmixturesshouldbeusedrather
thantheadditionofmorewater
•Whereverpossible,thecohesivenessandfinishibilityofconcreteshouldbe
improvedbyincreasingsand/aggregateratiothanbyincreasingthe
proportionofthefineparticlesinthesand.

10. Workability

11. Strength and Durability
Strengthanddurability
•Strengthanddurabilityrequirelowerw/cratio.Itisusuallyachieved
notbyincreasingthecementcontent,butbyloweringthewaterat
givencementcontent.Waterdemandcanbyloweredbythroughout
controloftheaggregategradingandbyusingwaterreducing
admixtures.

12. Strength and Durability

13. Grade of Concrete
•Theconcreteshallbeingradesdesignated
Group Grade designation Characteristics compressive strength
of 150 mm cube at28 days, N/mm2
OrdinaryConcrete M10
M15
M20
10
15
20
Standard Concrete M25
M30
M35
M40
M45
M50
M55
25
30
35
40
45
50
55
High Strength Concrete M60
M65
M70
M75
M80
60
65
70
75
80

14. What is M 20 ?
•MreferstoMix
•20referstocharacteristiccompressivestrengthof150mm
cubeat28daysinN/mm
2
•TheminimumGradeofPlainConcrete(PCC)shallbe15
N/mm
2
•TheminimumgradeofreinforcedConcrete(RCC)shallbe
20N/mm
2

15. Nominal Concrete Mixes
and
Design mix concrete
NominalMixConcrete
•Thewideuseofconcreteasconstructionmaterialshasledto
theuseofmixesoffixedproportion,whichensures
adequatestrength.Thesemixesarecallednominalmixes.
•TheyoffersimplicityandUndernormalcircumstances,has
marginofstrengthabovethatspecified.
•Nominalmixconcretemaybeusedforconcreteofgrades
M5,M7.5,M10,M15andM20.

16. Nominal Concrete Mixes
and
Design mix concrete

17. Proportions of Ingredients in Nominal Mixes
•Theproportionsofmaterialsfornominalmixshallbeinaccordance
Grade Proportions
C: FA: CA
M
5 1: 5:10
M
7.5 1:4:8
M
10 1:3:6
M
15 1:2:4
M
20 1:1.5:3

18. Design Mix Concrete
•Theconcretemixproducedunderqualitycontrolkeepinginview
thestrength,durability,andworkabilityiscalledthedesignMix.
•Othersfactorslikecompactionequipment'savailable,curingmethod
adopted,typeofcement,qualityoffineandcoarseaggregateetc.
havetobekeptinmindbeforearrivingatthemixproportion.
•Thedesignmixorcontrolledmixisbeingusedmoreandmorein
varietyofimportantstructures,becauseofbetterstrength,reduced
variability,leanermixedwithconsequenteconomy,aswellas
greaterassuranceoftheresultantquality.

19. Design Mix Concrete

20. Factors Influencing Choice of Mix Design
•AccordingtoIS456:2000andIS1343:1980theimportantinfluencingthe
designofconcretemixare
•GradeofConcrete
•TypeofCement
•MaximumnominalSizeofAggregate
•GradingofCombinedaggregate
•MaximumWater/CementRatio
•Workability
•Durability
•QualityControl.

21. Factors Influencing Choice of Mix Design
GradeofConcrete
•Thegradeofconcretegivescharacteristiccompressive
strengthofconcrete.Itisoneoftheimportantfactor
influencingthemixdesign
•ThegradeM20denotescharacteristiccompressivestrength
f
ckof20N/mm
2
.Dependinguponthedegreeofcontrol
availableatsite,theconcretemixistobedesignedfora
targetmeancompressivestrength(f
ck)applyingsuitable
standarddeviation.

22. Factors Influencing Choice of Mix Design

23. Factors Influencing Choice of Mix Design
TypeofCement
•Therateofdevelopmentofstrengthofconcreteis
influencedbythetypeofcement.
•Thehigherthestrengthofcementusedinconcrete,lesser
willbethecementcontent.Theuseof43gradeand53
gradeofcement,givessavingincementconsumptionas
muchas15%and25%respectively,ascomparedto33
gradeofcement.ForconcreteofgradeM
25itisadvisableto
use43and53gradeofcement.

24. Types of Cement

25. Factors Influencing Choice of Mix Design
MaximumNominalSizeofAggregates
•ThemaximumsizeofC.Aisdeterminedbysieveanalysis.Itisdesignatedbythe
sievesizehigherthanlargersizeonwhich15%ormoreoftheaggregateis
retained.ThemaximumnominalsizeofC.A.shouldnotbemorethanone-forth
ofminimumthicknessofthemember.
•Forheavilyreinforcedconcretemembersasinthecaseofribsofmainbeams,
thenominalmaximumsizeoftheaggregateshouldusuallyberestrictedtosum
lessthantheminimumcleardistancebetweenthemainbarsor5mmlessthe
minimumcovertothereinforcement,whoeverissmaller.
•Theworkabilityofconcreteincreaseswithanincreaseinthemaximumsizeof
aggregate.Butthesmallersizeofaggregatesprovidelargersurfaceareafor
bondingwiththemortarmatrixwhichgiveshigherstrength.

26. Factors Influencing Choice of Mix Design
GradingofCombinedAggregates
•Therelativeproportionsofthefineandcoarseaggregatein
aconcretemixisoneoftheimportantfactorsaffectingthe
strengthofconcrete.
•Fordenseconcrete,itisessentialthatthefineandcoarse
aggregatebewellgraded.Inthecasewhentheaggregate
availablefromnaturalsourcesdonotconfirmtothe
specifiedgrading,theproportioningoftwoormore
aggregatebecomeessential

27. Grading of Combined Aggregates

28. Factors Influencing Choice of Mix Design
MaximumWater/CementRatio
•Abram’swater/Cementratiostatesthatforanygivenconditionof
test,thestrengthofaworkabilityconcretemixisdependentonlyon
water/cementratio.Thelowerthewater/Cementratio,thegreateris
thecompressivestrength
Workability
•Workabilityoffreshconcretedeterminesthecasewithwhicha
concretemixturecanbemixed,transported,placed,compactedand
finishedwithoutharmfulsegregationandbleeding.

29. Factors Influencing Choice of Mix Design
Durability
•Durabilityrequirelowwater/Cementratio.Itisusually
achievednotbyincreasingthecementcontent,butby
loweringthewaterdemandatagivencementcontent.
•Waterdemandcanbeloweredbythroughcontrolofthe
aggregategradingandbyusingwaterreducingadmixtures

30. Method of Concrete Mix Design
•Someofthecommonlyusedmixdesignmethodsare
•I.S.Method
•A.C.Imethod
•RoadNote4method(U.K.Method)
•IRC44method
•Arbitrarymethod
•MaximumDensitymethod
•Finenessmodulusmethod
•SurfaceareaMethod
•NixdesignforhighstrengthConcrete
•MixdesignforpumpableConcrete
•DOE(British)Mixdesignmethod

31. IS Method of Mix Design
•TheBureauofIndianStandards,recommendedasetofprocedurefor
designofconcretemix.Theprocedureisbasedontheresearchwork
carriedoutatnationallaboratories.
•Dataformixdesign
•Thefollowingbasicdataarerequiredtobespecifiedfordesignaconcrete
mix
•CharacteristicCompressivestrengthonlyafewspecifiedproportionsof
testresultsareexpectedtofallofconcreteat28days(fck)
•Degreeofworkabilitydesired
•Limitationonwater/CementRatiowiththeminimumcementtoensure
adequatedurability
•Typeandmaximumsizeofaggregatetobeused.
•Standarddeviationsofcompressivestrengthofconcrete.

32. IS Method of Mix Design
•TargetStrengthforMixDesign
•Thetargetaveragecompressivestrength(fck)ofconcreteat28daysis
givenby
•F
ck=f
ck+t.s
Where,
•F
ck=targetaveragecompressivestrengthat28days
•F
ck=characteristicscompressivestrengthat28days
•s=Standarddeviation
•t=astasticalvalue,dependingupontheacceptedproportionoflowresults
andthenumberoftests.

33. IS Method of Mix Design
•AccordingtoIs456:2000andIS1343:1980te
characteristicstrengthisdefinedasthevaluebelowwhich
notmorethan5percentofresultsareexpectedtofall.In
suchcasestheaboveequationreducedto
•F
ck=f
ck+1.65s
•Thevalueofstandarddeviationisobtainedfromthetable

34. IS Method of Mix Design

35. IS Method of Mix Design
Step-II
SelectionofWater–CementRatio
•Sincedifferentcementsandaggregatesofdifferentmaximumsizes,
grading,surfacetextureshapeandothercharacteristicsmayproduce
concreteofdifferentcompressivestrengthforthesamefreewater
cementratio,therelationshipbetweenstrengthandfreewater
cementratioshouldpreferablebeestablishedforthematerial
actuallytobeused.Intheabsenceofsuchdata,thepreliminaryfree
water-cementratiocorrespondingtothetargetstrengthat28days
maybeselectedfromtherelationshipshownbelow

36. IS Method of Mix Design

37. IS Method of Mix Design
•Alternatively,thepreliminaryfreewatercementratioby
masscorrespondingtotheaveragestrengthmaybeselected
fromtherelationshipshownbelowusingthecurve
correspondingtothe28dayscementstrengthtobeusedfor
thepurpose.However,thiswillneed28daysfortestingof
cement.

38. IS Method of Mix Design

39. IS Method of Mix Design
•Thefreewater-cementratiothusselectedshouldbechecked
againstlimitingwater-cementratiofortherequirementsof
durabilityaspertable5.4andthelowerofthetwovalues
shouldbeadopted.

40. IS Method of Mix Design

41. IS Method of Mix Design
Step3EstimationofAirContent
•Approximateamountofentrappedairtobeexpectedinnormal
concreteisgivenintable9.6
Nominal Maximum Size of AggregatesEntrapped Air, as percentage of volume
of concrete
10 3 %
20 2 %
40 1 %

42. IS Method of Mix Design
SelectionofWaterContentandfinetototalaggregateratio
•Forthedesiredworkabilitythequantityofmixingwaterperunit
volumeofconcreteandtheratiooffineaggregate(sand)tototal
aggregatebyabsolutevolumearetobeestimatedfromtablebelowas
applicable.Dependinguponthenominalmaximumsizeandtypeof
aggregate.

43. IS Method of Mix Design
•ApproximateSandandwaterContentperCubicMetreofConcrete
forGradesuptoM
35W/C=0.6Workability=0.8C.F
Nominal Maximumsize
of aggregate (mm)
Water Content per
cubic metre of concrete
(kg)
Sand as percentage of
total aggregate by
absolutevolume
10 208 40
20 186 35
40 165 30

44. IS Method of Mix Design
•ApproximateSandandWaterContentpercubicmetreofconcrete
forgradesaboveM
35W/C=0.35Workability=0.8C.F.
Nominal Maximum size
of Aggregates
Water Content per cubic
metre of concrete (kg)
Sand as percentage total
aggregate by absolute
volume of (%)
10 200 28
20 180 25

45. IS Method of Mix Design
•Adjustmentofvaluesinwatercontentandsandpercentageforother
conditions
Change in ConditionAdjustment Required
Water Content Percentage sand in total aggregate
For sand confirming to
grading Zones I , III
and IV
0 + 1.5 percent for zone I
-1.5 percent for zone III
-3.0 for zone IV
Increase or decrease in
values of compacting
factor by 0.1
±3 % 0
Each 0.05 increase or
decrease in free water
cement ratio
0 ±1 %
-15 kg/m
3
-7 %
For rounded
aggregates

46. Calculation of Cement Content
•Thecementcontentperunitvolumeofconcretemaybe
calculatedfromthefreewater-cementratioobtainedin
step-2,andthequantityofwaterperunitvolumeof
concreteobtainedinstep-4
•Thecementcontentsoobtainedshouldbecheckedagainst
theminimumcementcontentfortherequirementof
durabilityaspertable5IS456:2000andthegreaterofthe
twovalueisadopted.

47. Step -6 Calculation of Aggregate Content
•Withthequantitiesofwaterandcementperunitvolumeofconcreteand
theratiooffinetototalaggregatealreadydetermined,thetotalaggregate
contentperunitvolumeofconcretemaybecalculatedfromthefollowing
equations
•V=[W+C+1xfa]x1forfineaggregate………………………… 1
ScpSfa1000
And
V=[W+C+1 xCa]x1forcoarseaggregate………… ..2
Sc(1-p) Sca1000

48. Step -6 Calculation of Aggregate Content
Where,
•V=Absolutevolumeoffreshconcrete(m
3
)
•W=MassofWater(kg)perm
3
ofconcrete
•C=MassofCement(Kg)perm
3
ofconcrete
•Sc=Specificgravityofcementsay3.15
•P=ratiooffineaggregatetototalaggregatebyabsolutevolume
•FaandCa=Totalmassesoffineaggregateandcoarseaggregate(kg)/m
3
ofconcretemassrespectively
•Sfa,Sca=Specificgravitiesofsaturatedsurfacedryfineaggregateand
coarseaggregaterespectively
•NormallySfa=2.6andSca=2.7

49. Trial Mixes
•TheCalculatedmixproportionsshallbecheckedbymeans
oftrialbatches.Thequantityofmaterialshouldbesufficient
foratleastthree150mmsizecubeconcretespecimens

50. Example
•UsingI.SMethoddesignaconcretemixforreinforcedconcrete
structureforthefollowingrequirement.
•Designdata
•Characteristiccompressivestrength=20N/mm
2
•Maximumsizeofaggregates=20mm(angular)
•Degreeofworkability=0.9CF
•DegreeofqualityControl=Good
•Typeofexposure=Mild

51. Example
•TestdataforMaterial
•Cementused=OrdinaryPortlandcementofgrade43with28days
strength51N/mm
2
•SG=3.15
•BulkDensity=1450kg/m
3
•Aggregate FineAggregate CoarseAggregate
•SG 2.66 2.75
•BulkDensity 1700 1800
•Waterabsorption 1 0.5
•FreeMoisture 2 Nil

52. Example
Step-I TargetMeanStrength
•F
ck=f
ck+ts
•f
ck=20N/mm
2
•T=1.65
•S=4fromtable9.5forM
20
•Therefore
•F
ck=20+1.65x4
•=26.6N/mm
2
(Mpa)

53. Example
Step-II
•SelectionofWaterCementRatio
•Fromthefigthefreewatercementratiorequiredforthetargetmean
strengthof26.6N/mm
2
is0.5
•Fromfig,for28daysstrengthofcement51N/mm
2
,forcurveDthe
freewatercementratiois0.52
•Fromtablethemaximumfreewatercementratioformildexposure
is0.55
•Hencethefreewatercementratioistakenastheminimumofabove
threevaluesi.e.w/c=0.5

54. Example
Step–III
•EstimationofAirContent
•FormaximumSizeofaggregateof20mm,theaircontentistakenas
2%

55. Example
Step-4SelectionofwaterandSandContent
•Fromtable9.7for20mmnominalmaximumsizeaggregateand
sandconfirmingtogradingzone–IIwatercontentpercubicmetre
ofconcrete=186kgandsandcontentaspercentageoftotal
aggregatebyabsolutevolume=35%
•Water=186kg/m
3
ofconcrete
•Sand=35%oftotalaggregatebyabsolutevolume

56. Example
•Forchangeinvaluesinwatercementratio,compactionfactorand
sandbelongingtozoneIIIthefollowingadjustmentsrequired.
ChangeinCondition WaterContent PercentageSandin
totalaggregate
ForDecreaseinwatercementratio
(0.6-0.5)thatis0.1
0.1x1=2.0
0.05
0 -2.0
Forincreaseincompactingfactor(0.9-
0.8)=0.1
0.1x3=3
0.1
+3 0
ForSandconformingtoZoneIII 0 -1.5
+3 -3.5

57. Example
•RequiredWaterContent=186+(186x3/100)
•=186+5.58
•=191.6lit/m
3
=
requiredsandcontentaspercentageoftotalaggregatebyabsolute
volume=35–3.5
=
31.5%

58. Example
DeterminationofCementContent
•WaterCementratio=0.5
•Water=191.6lit=191.6kg
•ThereforeW/c=0.5
•191.6=0.5
•C
•C=383.4kg/m
3
•=383kg/m
3
>300kg/m
3
thereforeO.K.

59. Example
Determination of fine and coarse Aggregates
•Consider volume of Concrete= 1 m
3
•But entrapped air in wet concrete = 2 %
•Therefore volume of fresh concrete= 1 –2
100
1-0.02
V= 0.98 m
3

60. Example
•Withthequantitiesofwaterandcementperunitvolumeofconcreteand
theratiooffinetototalaggregatealreadydetermined,thetotalaggregate
contentperunitvolumeofconcretemaybecalculatedfromthefollowing
equations
•V=[W+C+1xfa]x1 forfineaggregate……………… 1
Scp Sfa1000
0.98=[191.6+383+1+fa]x1
3.150.3152.661000
980=313.187+1.19fa
fa=558.75kgmassofF.A

61. Example
And
V=[W+C+1 xC
a]x1forcoarseaggregate………… ..2
S
c(1-p) S
ca1000
0.98=[191.6+383x1 x C
a]x1
3.15(1-0.315) 2.751000
980=313.187+0.5308C
a
C
a=1256.24kgmassofC.A

62. Example
Water Cement F.A C.A
191.6 li 383 kg 558.75 kg 1256.24 kg
0.5 1 1.46 3.28
Water Cement F.A C.A
383=0.264m
3
1450
558.75=0.328m
3
1700
1256.24=0.698m
3
1800
0.5 1.0 1.242 2.644

63. Example
Water Cement F.A C.A
25 li 50 kg 73 kg 164 kg

64. Example
•DesignaConcretemixforM25gradeasperIS10262forthe
followingdata:
•CharacteristicCompressiveStrengthinthefieldat28days25
N/mm
2
•MaximumSizeofAggregate=20mm
•DegreeofWorkability0.9CF
•DegreeofQualityControl=Good
•TypeofExposure=Moderate

65. Example
TestdataforMaterial
•CementUsed:OrdinaryPortlandCementofGrade33satisfyingtherequirementofIS:269-1989
•SpecificGravityofCement:3.15
•SpecificGravity;
•CoarseAggregate=2.65
•FineAggregate=2.6
•Waterabsorption
•CoarseAggregate0.6%
•Fineaggregate=1.2%
•Freemoisture
•CoarseaggregateNil
•Fineaggregate2%
•CAconformtotable2ofIS383-1970FAisnaturalriverSandConfirmingtoZoneIofTable383-1970

66. Example
Step-I
•TargetmeanStrengthofConcrete
•Fck=fck+ts
•fck=25N/mm
2
•T=1.65fromtable9.4
•S=4.0fromtable9.5forM25gradeofconcrete
•Fck=25+1.65x4
•=31.6N/mm
2

67. Example
Step-2
•SelectionofWater-CementRatio
•Fromfig9.1thefreewatercementratiorequiredforthetargetmean
strengthof31.6N/mm
2
is0.44
•Now,fromtable5.4themaximumfreewatercementratioformoderate
exposureis0.5
•Hence,thefreewatercementratioistakenastheminimumofabovetwo
valuei.e
•W=0.44
C

68. Example
StepIIIEstimationofairContent
•FormaximumSizeofAggregateof20mm,theaircontentistakenas
2.0%

69. Example
Step-4
•SelectionofWaterandSandContent
•Fromtable9.7for20mmnominalmaximumsizeaggregatesand
sandconfirmingtogradingZone-II,watercontentpercubicmetre
ofconcrete=186kgandsandcontentaspercentageoftotal
aggregatebyabsolutevolume=35%i.e.
•Water=186kg/m
3
•Sand=35%oftotalaggregatebyabsoluteVolume.

70. Example
•ForChangeinvaluesinwater-Cementratio,compactionfactorand
sandbelongingtozoneIthefollowingadjustmentsarerequired.

71. Change in Condition Adjustment Required
Water Content Percentage Sand in total
Aggregate
(i)For Decrease in Water-Cement ratio (0.6
–0.44) thatis 0.16
Therefore 0.16 x 1 = 3.2
0.05
0 -3.2
(ii) For Increase in Compacting factor (0.9 -
0.8)= 0.1
Therefore 0.1 x 3 = 3.0
0.1
+3 0
(iii) For Sand Conforming to Zone-I of table
4 of IS 383-1970
0 +1.5

72. Example
•RequiredwaterContent=186+(186x3)
100
=191.6lit/m
3
RequiredSandContentasPercentageofTotalaggregatebyabsoluter
Volume
p=35–1.7
=
33.3%

73. Example
Step-VDeterminationofCementContent
•WaterCementRatio=0.44
•Water=191.6lit=191.6kg
•Therefore,
•W=0.44
C
191.6=0.44
C
C=435.45kg/m
3
>300kg/m
3
Thiscementcontentisadequatefor‘ModerateExposure’condition,
accordingtotable5IS456-2000)

74. Example
DeterminationoffineandCoarsecontent:
•Considervolumeofconcrete=1m
3
But,entrappedairinwetconcrete=2%
Therefore,absolutevolumeoffreshconcrete=1–2
100
=1–0.02
V=0.98m
3
Therefore,

75. Example
•V=[W+C+1xf
a]x1forfineaggregate…1
S
cp S
fa1000
And
0.98=[191.6+436+1+fa]x1
3.150.33 2.6 1000
980=191.6+138.41+1.15fa
fa=562.76kg
=563kgmassofF.A.

76. Example
Similarly,
V=[W+C+1 xC
a]x1forcoarseaggregate……..2
S
c(1-p) S
ca1000
•0.98=[191.6+436x1xCa]x1
3.15(1-0.333) 2.65 1000
980=191.6+138.41+0.5657Ca
Ca=1149kg/m
3
massofC.A.

77. Example
•Mix Proportions (By Mass)
Water Cement F.A. C.A
191.6 li 436 kg 563 kg 1149 kg
0.44 1 1.29 2.64

78. Example
Water Cement F.A. C.A
22 li 50 kg 64.5 kg 132 kg

79. Example
Step8AdjustmentforwaterabsorptionandfreesurfacemoistureinF.A.andC.A
•ForwaterCementratioof0.44quantityofwaterrequired=22lit
•C.Aabsorbs0.6%ofwaterbymass
•Thereforeextraquantityofwatertobeadded
•0.6x132=0.792lit(+)
100
F.Acontains2%freemoisturebymass
Quantityofwatertobededucted
=2x64.5=1.29(-)
100
Actualquantityofwatertobeadded
=22+0.792–1.29
=21.5lit

80. Example
•Actualquantityofsand(FA)requiredafterallowingformassoffree
water
•=64.5+1.29=65.79kg
•ActualquantityofC.Arequired
•=132-0.792
•=131.21kg
Water Cement F.A. C.A
21.50li 50 kg 65.79 kg 131.21kg

81. Example
•DesignaconcretemixfromthefollowingdatabyI.S.method
•TargetmeanStrength=35N/mm
2
•MaximumSizeofAggregate=20mm
•W/Cratio=0.43
•Waterrequiredperm
3
ofconcrete=190kg
•SandaspercentageoftotalaggregatebyabsoluteVolume=35%
•Entrappedairinconcrete=2%
•SpgravityofCement=3.15
•Spgravityoffineaggregate=2.6
•SpgravityofCoarseaggregate.=2.7

82. Example
Step-ITargetmeanStrength
•F
ck=35N/mm
2
Step-IISelectionofWater-CementRatio:
•W/Cratio=0.43
Step-IIIEstimationofairContent
•Entrappedair=2%
Step-IV
•SelectionofwaterandsandContent
•Quantityofwaterperm
3
ofconcrete=190kg
•SandContent=35%oftotalaggregatebyabsoluteVolume

83. Example
Step-V
•CementContent
•Water-CementRatio=0.43
•Water=190kg
•W=0.43
c
190=0.43
C
C=441.86kg/m
3

84. Example
DeterminationofF.AandC.AContent
•ConsiderVolumeofConcrete=1m
3
•But,entrappedair=2%
•ThereforeAbsoluteVolumeofpressConcrete
•V=1–2
100
V=0.98m
3

85. Example
•V=[W+C+1xfa]x1forfineaggregate……………… 1
Scp Sfa1000
0.98=[190+442+1+fa]x1
3.150.352.61000
0.98=[190+140.32+1.098fa]x1
1000
fa=591.69kg/m
3
fa=592kg/m
3
MassofFA

86. Example
Similarly,
V=[W+C+1 xC
a]x1forcoarseaggregate……..2
S
c(1-p) S
ca1000
•0.98=[190+442x1 xCa]x1
• 3.14(1-0.35) 2.71000
•980=190+140.32+0.569Ca
•Ca=1142kg/m
3
MassofCA

87. Example
•Mix Proportion (by mass)
•Quantity for 1 bag of Cement
Water Cement F.A C.A
190 442 592 1142
0.43 1 1.34 2.58
Water Cement F.A C.A
21.5 50 67 129

88. The ACI Method of Mix Design
•IntheUSAthemethodsuggestedbyACIiswidelyused.It
hastheadvantagesofsimplicityinthatitappliesequally
well,andwithmoreorlessidenticalproceduretorounded
orangularaggregate,tonormalorlightweightaggregate
andtoair-entrainedornon-air-entrainedconcretes.
•TheACImethodisbasedonthefactthatforagivensizeof
wellgradedaggregateswatercontentislargelyindependent
ofmixproportions,i.e.Watercontentregardlessof
variationinwater/cementratioandcementcontent.

89. The ACI Method of Mix Design
•Thismethodassumesthattheoptimumratioofthebulk
volumeofcoarseaggregatesandonthegradingoffineness
aggregatesregardlessofshapeofparticles.Thismethodalso
assumesthatevenaftercompletecompactionisdone,a
definitepercentageofairremainswhichisinversely
proportionaltothemaximumsizeofaggregate.

90. The ACI Method of Mix Design
•ThestepsbystepsoperationintheACImethodare
Step-1Datatobecollected
•FinenessmodulusofFA
•UnitweightofdryCA
•SpecificgravityofFAandCAsaturatedsurfacedrycondition.
•SpecificgravityofCement
•AbsorptionscharacteristicsofbothCAandFA

91. The ACI Method of Mix Design
Step-2
•CalculationmeandesignStrength,fromtheminimumstrength
specified,usingstandarddeviation:
•f
m=f
min+K.S
•Where,
•F
m=Specifiedminimumstrength(CharacteristicStrength)
•K=Constantdependencyupontheprobabilityofcertainnoofresults
likelytofallf
ck=takenfromtable9.4
•S=StandardDeviationfromtable9.5

92. IS Method of Mix Design

93. The ACI Method of Mix Design
Step-3EstimationofWater-CementRatio
•WaterCementratioisestimatedfromtable9.10forthemeandesign
Strength.

94. The ACI Method of Mix Design
Average Compressive Strength at
28 days
Effective Water-Cement Ratio (By Mass)
Non-Air Entrained Concrete Air-entrained Concrete
45 0.38 -
40 0.43 -
35 0.48 0.4
30 0.55 0.46
25 0.62 0.53
20 0.7 0.61
15 0.8 0.71

95. The ACI Method of Mix Design
•ThewaterCementratioobtainedfromStrengthpointof
viewistobecheckedagainstmaximumW/CRatiogivenfor
specialexposureconditiongivenintable9.11andminimum
ofthetwoistobeadopted.

96. The ACI Method of Mix Design
•RequirementofACIforW/CRatioandStrengthforSpecialExposure
Condition

97. ExposureCondition MaximumW/Cratio,normaldensity
aggregateconcrete
MinimumDesignStrength,low
DensityaggregateConcrete,MPA
ConcreteIntendedtobeWatertight
(a)ExposedtofreshWater
(b)ExposedtobrackishorseaWater
0.5
0.45
25
30
ConcreteExposedtofreezingandThawinginamoistCondition:
(a)Kerbs,gutters,guardrailsorthin
sections
0.45 30
Otherelements 0.5 25
Inpresenceofde-icingchemicals0.45 30
Forcorrosionprotectionof
reinforcedconcreteexposedtode-
icingsalts,brackishwater,seawater
orsprayfromthesources.
0.4 30

98. The ACI Method of Mix Design
•DecidemaximumsizeofaggregatetobeUsed.GenerallyRCCwork
20mmandPre-stressedConcrete10mmSizeareUsed
•DecideWorkabilityintermsofslumpforthetypeofjobinhand.
Generalguidancecanbetakenfromtable9.12.

99. The ACI Method of Mix Design
Type of Construction Range of slump mm
Reinforced foundation walls and footings 20-80
Plain footing, cassionsand substructure wall 20-80
Beams and Reinforced Wall 20-100
BuildingColumn 20-100
Pavement andSlabs 20-80
MassConcrete 20-80

100. The ACI Method of Mix Design
Step-4MinimumWaterContentandentrappedaircontent:
•Decidemaximumsizeofaggregatetobeused.GenerallyforRCC
work20mmandforpre-stressedconcrete10mmsizeareused.
•Decideworkabilityintermsofslumpforthetypeofjobinhand.
Recommendedvalueofslumpforvarioustypesofconstructionas
givenintable9.12

101. The ACI Method of Mix Design
Step-5CementContent
•CementContentiscomputedbydividingthewatercontentbythe
water/CementRatio
Step-6
•BulkVolumeofDryRoddedCoarseAggregateperUnitVolumeof
Concrete
•Table9.13foradecidedvalueofslumpandmaximumsizeof
aggregate,decidethemixingwatercontentandentrappedair
content.

102. Table 9.13
WorkabilityWater Content, kg/m
3
of Concrete for indicated maximum aggregate Size
Non-air entrained Concrete
Workability10
mm
12.5 mm20mm 25 mm 40 mm 50 m 70 mm 150 mm
Slump30-50
mm
205 200 185 180 160 155 145 125
80-100 mm225 215 200 195 175 170 160 140
150-180 mm240 230 210 205 185 180 170 -
Approx
entrapped air
content
3 2.5 2 1.5 1 0.5 0.3 0,2

103. Table 9.13
WorkabilityWaterContent,kg/m
3
ofConcreteforindicatedmaximumaggregateSize
AirentrainedConcrete
Workability10
mm
12.5mm20mm 25mm 40mm 50m 70mm 150mm
Slump30-50
mm
180175 165 160 145 140 135 120
80-100mm 200190 180 175 160 155 150 135
150-180mm215205 190 185 170 165 160 -

104. Table 9.13
WorkabilityWaterContent,kg/m
3
ofConcreteforindicatedmaximumaggregateSize
AirentrainedConcrete
Workabili
ty
WaterContent,kg/m
3
ofConcreteforindicatedmaximumaggregateSize
AirentrainedConcrete
10mm 12.5mm20mm 25mm 40mm 50m 70mm 150mm
Slump
30-50
mm
180 175 165 160 145 140 135 120
80-100
mm
200 190 180 175 160 155 150 135
150-180
mm
215 205 190 185 170 165 160 -
Recomme
nded air
Content
Mild
Exposure
4.5 4 3.5 3.0 2.5 2.0 1.5 1.0
Moderate
Exposure
6.0 5.5 5.0 4.5 4.5 4.0 3.5 3.0
Extreme
Exposure
7.5 7.0 6.0 6.0 5.5 5.0 4.5 4.0

105. The ACI Method of Mix Design
•Knowingthevaluesofmaximumsizeofcoarseaggregatesand
finenessmodulus(FM)offineaggregate,bulkvolumeofdryrodded
aggregateperunitvolumeofconcreteisselectedfromtable9.14
•DryBulkofCoarseAggregateperunitVolumeofConcreteasGiven
byACI

106. Maximum Size of
Aggregate
Bulk Volume of Dry RoddedCoarse Aggregate per unit volume of concrete for fineness
modulus of sand
FM 2.4 2.6 2.8 3.0
10 0.5 0.48 0.46 0.44
12.5 0.59 0.57 0.55 0.53
20 0.66 0.64 0.62 0.6
25 0.71 0.69 0.67 0.65
40 0.75 0.73 0.71 0.69
50 0.78 0.76 0.74 0.72
70 0.82 0.8 0.78 0.76
150 0.87 0.85 0.83 0.81
(a)The value given will produce a mix that issuitable for reinforced concrete construction. For less workable
concrete the value may be increased by 10 percent for workable concrete such as pumpableconcrete the
value may be reduced by upto10 percent
(b)From the minimum strength specified estimate the average design strength either by using coefficient of
variation
(c)Find the water/cement ratio from the table 9.14

107. The ACI Method of Mix Design
Step-7
•TheweightofCApercubicmetreofConcreteisCalculatedby
multiplyingthebulkVolumewithbulkdensityofCA
Step-8EstimateofDensityoffreshConcrete
•KnowingthemaximumSizeofCoarseAggregates,thedensityof
freshConcreteisestimatedas

108. The ACI Method of Mix Design
•FirstEstimateofDensityofFreshConcreteasGivenbyACI
Maximum Size of
Aggregates
Non air-entrained air
kg/m
3
Airentrainedkg/m
3
10 2285 2190
12.5 2315 2235
20 2355 2280
25 2375 2315
40 2420 2355
50 2445 2375
70 2465 2400

109. The ACI Method of Mix Design
Step-9
•Absolutevolumesofingredientspercubicmetreofconcreteareobtained
byknowingthespecificgravityofcement,waterCAandFA
Step-10
•Trialmixproportionsarecalculatedandadjustmentsforfieldconditions
likefreemoistureandwaterabsorptionbyaggregatesaremade.
Step-11
•Atrialmixisthenmadetostudythepropertiesofconcreteinrespectof
workability,cohesiveness,finishingqualityand28dayscompressive
strength.TheproportionofCAandFAmaybechangedtogetdesired
properties.

110. Example-I
DesignaConcretemixUsingACImethodforamulti-Storiedbuildingforthefollowingdata
•28dayscharacteristicCompressiveStrength=30Mpa
•TypeofCementAvailable=OrdinaryPortlandCement
•DesiredSlump=80-100mm
•MaximumSizeofaggregate=20mm
•StandardDeviationfrompastRecords=4.5Mpa
•SpecificGravitiesforFA=2.65
•SpecificGravityforCA=2.7
•ForCement=3.15
•BulkdensityofCA=1600kg/m
3
•FinenessmodulusofFA=2.8
•CAabsorbed1%moistureandsand
•Contains1.5%freesurfacemoisture
•Assumeanyotherdata

111. Example-I
Solution
Step-I
•MeanDesignStrength
•fm=fmin+K.S
•=30+1.65x4.5
•=37.425Mpa
•Fromtable9.4
•Assume5%oftestresultsareexpectedfall
•K=1.65

112. Example-I
Step-II
•EstimationofWater-CementRatio
•Fromtable9.1formeandesignstrengthof37.425Mpa,the
estimatedW/Cratiois0.45
•Fromtable9.11,forexposurecondition“concreteintendedtobe
watertightandexposedtofreshwater”,themaximum
•w/Cratiois0.5
•Henceadoptawatercementratioof0.45

113. The ACI Method of Mix Design
Average Compressive Strength at
28 days
Effective Water-Cement Ratio (By Mass)
Non-Air Entrained Concrete Air-entrained Concrete
45 0.38 -
40 0.43 -
35 0.48 0.4
30 0.55 0.46
25 0.62 0.53
20 0.7 0.61
15 0.8 0.71

114. ExposureCondition MaximumW/Cratio,normaldensity
aggregateconcrete
MinimumDesignStrength,low
DensityaggregateConcrete,MPA
ConcreteIntendedtobeWatertight
(a)ExposedtofreshWater
(b)ExposedtobrackishorseaWater
0.5
0.45
25
30
ConcreteExposedtofreezingandThawinginamoistCondition:
(a)Kerbs,gutters,guardrailsorthin
sections
0.45 30
Otherelements 0.5 25
Inpresenceofde-icingchemicals0.45 30
Forcorrosionprotectionof
reinforcedconcreteexposedtode-
icingsalts,brackishwater,seawater
orsprayfromthesources.
0.4 30

115. Example-I
•Mixingwatercontentandentrappedaircontent
•Maximumsizeofaggregates=20mm
•DesiredSlump=80-100
•Thereforefromtable9.13
•MixingwaterContent=200kg/m
3
ofConcrete
•EntrappedairContent=2%

116. Table 9.13
WorkabilityWater Content, kg/m
3
of Concrete for indicated maximum aggregate Size
Non-air entrained Concrete
Workability10
mm
12.5 mm20mm 25 mm 40 mm 50 m 70 mm 150 mm
Slump30-50
mm
205 200 185 180 160 155 145 125
80-100 mm225 215 200 195 175 170 160 140
150-180 mm240 230 210 205 185 180 170 -
Approx
entrapped air
content
3 2.5 2 1.5 1 0.5 0.3 0,2

117. Table 9.13
WorkabilityWaterContent,kg/m
3
ofConcreteforindicatedmaximumaggregateSize
AirentrainedConcrete
Workability10
mm
12.5mm20mm 25mm 40mm 50m 70mm 150mm
Slump30-50
mm
180175 165 160 145 140 135 120
80-100mm 200190 180 175 160 155 150 135
150-180mm215205 190 185 170 165 160 -

118. Table 9.13
Recomme
nded air
Content
Mild
Exposure
4.5 4 3.5 3.0 2.5 2.0 1.5 1.0
Moderate
Exposure
6.0 5.5 5.0 4.5 4.5 4.0 3.5 3.0
Extreme
Exposure
7.5 7.0 6.0 6.0 5.5 5.0 4.5 4.0

119. Example-I
Step-4
•CementContent
•W/Cratio=0.45
•200=0.45
C
C=445kg/m
3
Water=200kg/m
3
ofconcrete

120. Example-I
Step-5
•BulkVolumeofDryRoddedCA:
•MaximumSizeofCA=20mm
•FinenessmodulusofFA=2.8
•Thereforetable9.14
•ThebulkvolumeofdryroddedCAis0.62perunitvolumeof
Concrete

121. Maximum Size of
Aggregate
Bulk Volume of Dry RoddedCoarse Aggregate per unit volume of concrete for fineness
modulus of sand
FM 2.4 2.6 2.8 3.0
10 0.5 0.48 0.46 0.44
12.5 0.59 0.57 0.55 0.53
20 0.66 0.64 0.62 0.6
25 0.71 0.69 0.67 0.65
40 0.75 0.73 0.71 0.69
50 0.78 0.76 0.74 0.72
70 0.82 0.8 0.78 0.76
150 0.87 0.85 0.83 0.81
(a)The value given will produce a mix that issuitable for reinforced concrete construction. For less workable
concrete the value may be increased by 10 percent for workable concrete such as pumpableconcrete the
value may be reduced by upto10 percent
(b)From the minimum strength specified estimate the average design strength either by using coefficient of
variation
(c)Find the water/cement ratio from the table 9.14

122. Example-I
Step-6
•WeightofCA=0.62x1600
•=992kg/m
3
•ThereforedensityofCAis1600kg/m
3

123. Example-I
Step-7
•DrydensityoffreshConcrete
•FormaximumSizeofCA=200mmandnonairentrainedConcrete,
•Fromtable9.15drydensityoffreshConcrete
=2355kg/m
3

124. Example-I
Step-8
•MassofalltheknownIngredientofConcrete
•Massofwater=200kg/m
3
•MassofCement=445kg/m
3
•MassofCA=992kg/m
3
•MassofFA=2355-[200+445+992]
=718kg/m
3

125. Example-I
Sr.no Ingredient Mass,kg/m3 AbsoluteVolumem3
1 Cement 445 445= 0.141m
3
3.15x1000
2 Water 200 200= 0.2m
3
1x1000
3 CA 992 992 =0.367m
3
2.7x1000
4 EntrappedAir 2% 2x1=0.02%
100
TotalAbsoluteVolume 0.728m
3

126. •Hence,VolumeofFArequired=1-0.728
•=0.272m
3
•MassofFA=0.272x2.65x1000
•=720.8kg/m
3
•AdoptmassofFA=720.8kg/m
3
•=721kg/m
3
•Estimatedquantitiesofmaterialpercubicmetreofconcreteare
•Cement=445kg
•FA=721kg
•CA=992kg
•Water=200kg
•Total2358kg/m
3
ofConcrete

127. Example-I
•Density of fresh Concrete is 2358 kg/m
3
as against 2355
Water Cement F.A C.A
200 445 kg 721 kg 992 kg
0.45 1 1.62 2.23
Water Cement F.A C.A
22.5 kg 50 kg 81 kg 111.5

128. Example-I
•Adjustmentforwaterabsorptionandfreesurfacemoisture
•F.AContains1.5%freesurfacemoisture
•TotalsurfacemoistureofFA=1.5 x721
100
=10.82kg(-)
MassofFAinfieldcondition=721+10.82
=731.83kg/m
3
Say732kg/m3
CAabsorbs1%ofmoisture,
QuantityofwaterabsorbedbyCA=1x992
100
=9.92kg(+)
ThereforemassofCAinfieldCondition=992–9.92
=982kg/m3

129. Example-I
•NetQuantityofMixWater=200-10.82+9.92
=199.10kg
•Finalmixproportions(for1m
3
ofconcrete)
Water Cement F.A. C.A.
199.10 kg 445 kg 732 kg 982 kg

130. The British Method
•ThetraditionalBritishmethodhasbeenreplacedbythedepartmentofthe
environmentfornormalmixes,knownasDOE(British)mixdesignmethod.
•ThefollowingstepsareInvolvedinDOEMethod
Step-I
•FindthetargetmeanstrengthfromthespecifiedCharacteristicStrength
•f
t=f
ck+k.S
•Where,
•ft=targetmeanstrength
•fck=characteristicStrength
•S=StandardDeviation
•K=riskfactororprobabilityfactor
CONCRETE MIX DESIGN

131. Step-II
Determinationoffreewatercementratio
•Fromthegiventypeofcementandaggregate,obtainthecompressive
strengthofconcretecorrespondingtofreew/cratioof0.5
Type of
Cement
Type of Coarse
Aggregate
3 7 28 91
Ordinary or
Sulphate
Resisting
Cement
Uncrushed
Crushed
22
27
30
36
42
49
49
56
Rapid
Hardening
Portland
Cement
Uncrushed
Crushed
29
34
37
43
48
55
54
61
CONCRETE MIX DESIGN

132. •Nowadoptthepairofdatai.e.compressivestrengthreadfromtable
9.16andw/cratiomarkpoint‘P’.Throughthispointdrawadotted
curveparalleltoneighbouringcurve.Usingthisnewcurveweread
thew/cratioasagainsttargetstrengthftcalculatedinstep1
•Checkthisw/cratiofordurabilityconsiderationsandadoptthe
lowervalue
Minimum
grade
30 35 40 45 50
Maximu
m w/c
ratio
0.65 0.6 0.55 0.5 0.45
Maximu
mcement
content
275 300 325 350 400
CONCRETE MIX DESIGN

133. Fig.1Relationbetween
compressivestrength
andfreewatercement
ratio
markapointcorrespondingto
strengthf1,atwatercementratio0.5.
drawacurveparalleltothenearest
curve,throughthispoint
Usingthenewcurve,
Readoff(abscissa)thewatercement
ratio
correspondingtothetargetmean
strength(ordinate)
Freewater-cementratio
CONCRETE MIX DESIGN

134. Step-3
DeterminationofwaterContent
•Dependinguponthetypeandmaximumnominalsizeofaggregate
andworkabilitythewatercontentisestimatedas
•W=2Wfa+1Wca
3 3
•Where,
•Wfa=freewatercontentappropriatetothetypeoffineaggregate
•Wca=freewatercontentappropriatetothetypeofcoarseaggregate
CONCRETE MIX DESIGN

135. Level of
Workability
Very Low Low Medium High
Description Slump 0-10 10-30 30-60 60-180
Vee-bee >12 12-6 6-3 3-0
Compaction
Factor
0.75-0.85 0.85-0.9 0.9-0.93 >0.93
Maximum
Size of Agg
Type of
aggregate
Water Content
10 mm Uncrushed 150 180 205 225
Crushed 180 205 230 250
20 Uncrushed 135 160 180 195
Crushed 170 190 210 225
40 Uncrushed 115 140 160 175
Crushed 155 175 190 205
CONCRETE MIX DESIGN

136. •Reduction in water content when fly ash is Used
% of fly ashReduction inWater content Kg/m3
10 5 5 5 10
20 10 10 10 15
30 15 15 20 20
40 20 20 25 25
50 25 25 30 30
CONCRETE MIX DESIGN

137. Step4-DeterminationofCementContent
•TheCementContentifthemixiscalculatedfromtheselectedw/c
ratio
•CementContent=watercontent
W/Cratio
CONCRETE MIX DESIGN

138. Step-5
DeterminationofaggregateCementRatio
•Absolutevolumeoccupiedbytheaggregate
•=1-CementContent(kg)–WaterContent(kg)
1000xSc 1000xSw
Where,Sc=Specificgravityofcementparticles
ThereforeTotalaggregatecontent(kg/m
3
)
=absolutevolumeoccupiedbytheaggregatex1000xSa
WhereSa=Specificgravityofaggregate

139. CONCRETE MIX DESIGN

140. Step-6DeterminationofFAandCA
•Dependingonthefreewatercementratio,thenominalmaximumsizeof
coarseaggregate,theworkabilityandgradingzoneoffineaggregateis
determinedfromfig9.5(a),9.5(b)and9.5(c)
•OncetheproportionofFAisobtained,multiplyingbytheweightoftotal
aggregategivestheweightoffineaggregate.Thencoarseaggregateis
calculatedas
•Fineaggregatecontent=totalaggregatecontentxproportionoffine
aggregate
•Coarseaggregatecontent=Totalaggregatecontent–fineaggregate
content
CONCRETE MIX DESIGN

142. Determination of FA and CA

143. Determination of FA and CA

144. FIG 3
-
Recommended proportion of fine aggregate as a
function of free water
–
cement ratio

145. Proportion of Different sizes of CA
Aggregate 4.75-10 mm 10-20 mm 20-40 mm
Type-I 33 67 -
Type-II 18 27 55
CONCRETE MIX DESIGN

146. Step-7
DeterminationoffinalProportion
•Theproportionsoworkedoutshouldbetriedfortheirspecified
strengthandsuitableadjustmentaremadetoobtaintheproportion.
CONCRETE MIX DESIGN

147. Example
•DesignaConcretemixUsing,DOEMethodforareinforcedConcreteWorkfor
thefollowingdata:
•RequiredCharacteristicCompressiveStrength=35Mpaat28days
•TypeofCementUsed=SulphateResistingPortlandCement
•DesiredSlump=50mm
•MaximumSizeofAggregate=20mm
•TypeofAggregate=Uncrushed
•SpecificGravity=2.65
•FineaggregateconformstogradeZoneIIIwithpercentpassing600micron
sievebeing70%
•ExposureCondition=Moderate
•StandardDeviation=5.0DefectiveRate=5%
CONCRETE MIX DESIGN

148. Example
•MixDesignWithoutflyash:
•TargetMeanStrength:
•Ft=fck+kS
•fck=35N/mm
2
•StandardDeviation=5.0
•K=1.65
•ft=35+1.65x5
•=43.25N/mm
2
CONCRETE MIX DESIGN

149. Example
DeterminationoffreeWater-CementRatio
•FortypeofCementSulphateresistingPortlandcementanduncrushed
aggregate28dayscompressivestrengthfromtable9.16is42MPA
•ForCompressiveStrengthequalto42MPAandw/cratio0.5,mark‘P’in
figanddrawadottedcurveparalleltotheneighbouringcurveUsingthis
newcurveagainft=43.25N/mm
2
theW/Cratioisreadas0.48
•Fromtable9.17fromdurabilitypointofviewthemaximumw/cratiois
0.6
•HenceAdopttheminimumw/cratioas0.48
CONCRETE MIX DESIGN

150. Example
Step-3
•DeterminationofWaterContent:
•ForDesiredslump=50mm
•MaximumsizeofCA=20mm
•Fromtable9.18watercontentis180kg/m
3
CONCRETE MIX DESIGN

151. Example
Step-4DeterminationofCementContent:
•W/Cratioobtainedfromstep2is0.48andwateris180kg/m3
•W/C=0.48
•180=0.48
C
ThereforeC=375kg/m
3
ofConcrete
ThisissatisfactoryasitisgreaterthanminimumCementContentof
300kg/m
3
CONCRETE MIX DESIGN

152. Example
Step:5
•AggregateCementRatio
•Specificgravityofaggregateis2.65
•Thereforefig9.4wetdensityofconcreteis2400kg/m3
•Thereforemassoftotalaggregate
•=2400–180-375
•=1845kg/m3
•AlternativelyVolumeoccupiedbyaggregate
•=1-375 –180 =0.7009m3
100x3.151000x1
ThereforetotalAggregateContent
=0.7009x1000x2.65
=1875kg/m3
CONCRETE MIX DESIGN

153. Example
Step-6DeterminationofFAandCAContent
•For,Maximumsizeofaggregate=20mm
•Slump=50mm
•FreeW/Cratio=0.48
•PercentaggregatePassing
•600micronsieve=70%
•Fromfig9.5(b)theproportionoffineaggregatei.s30%
•MassofFA=30x1875=557kg/m3
• 100
•MassofCA=1875–557.1
• =1299.9kg/m3
•=1300kg/m
3
CONCRETE MIX DESIGN

154. Example
Step7
•TheestimatedQuantityare:
Water Cement F.A C.A
180 kg 375 kg 557 kg 1300 kg
0.48 1 1.485 3.46
CONCRETE MIX DESIGN

155. Road Note No. 4
Method Of Mix Design
CONCRETE MIX DESIGN

156. ROAD NOTE No. 4 METHOD OF MIX DESIGN
ProposedbytheRoadResearchLaboratory,UK(1950)
Introduction
Inthismethod,theaggregatetocementratiosareworkedoutonthebasisoftypeof
aggregate,maxsizeofaggregateanddifferentlevelsofworkability.
Therelativeproportionofaggregatesisworkedonbasisofcombinedgradingcurves.This
methodfacilitatesuseofdifferenttypesoffineandcoarseaggregatesinthesamemix.
Therelativeproportionofthesecanbeeasilycalculatedfromcombinedgradingcurves.
Thevaluesofaggregatetocementratioareavailableforangularroundedorirregular
coarseaggregate.
CONCRETE MIX DESIGN 156

157. Procedure
1.Theaveragecompressivestrengthofthemixtobedesignedisobtainedbyapplyingcontrolfactorstothe
minimumcompressivestrength.
2.w/cratioisreadfromcompressivestrengthv/sw/cratiograph.
3.Proportionofcombinedaggregatestocementisdeterminedfromtables,formaximumsize40mmand20
mm.
4.Iftheaggregateavailablediffersfromthestandardgrading,combineFAandCAsoastoproduceoneof
thestandardgrading.
5.Theproportionofcement,water,FAandCAisdeterminedfromknowingthewater/cementratioandthe
aggregate/cementratio.
6.Calculatethequantitiesofingredientsrequiredtoproduce1m
3
ofconcrete,bytheabsolutevolume
method,usingthespecificgravitiesofcementandaggregates.
CONCRETE MIX DESIGN 157

158. CONCRETE MIX DESIGN 158
Method In Detail
FindTheTargetMeanStrength
Concreteisdesignedforstrengthhigherthancharacteristicstrength
asamarginforstatisticalvariationinresultsandvariationindegreeof
controlexercisedatsite.Thishigherstrengthisdefinedasthetargetmean
strength.
Targetmeanstrength=Characteristicstrength+K*s

159. Determinewater/cementratio
TherelationbetweenTargetMeanStrengthandwatercementratio
fordifferentcementcurvesisgiveninIS10262
CONCRETE MIX DESIGN 159

160. CONCRETE MIX DESIGN 160
Finding cement content

161. CONCRETE MIX DESIGN 161
The Relative Proportion Are Worked Out
Atrialproportionistakenandcombinedgradationisworkedoutfor
e.g.
35%fineaggregate20%10mmdownaggregate,45%20mmdown
aggregate.

162. CONCRETE MIX DESIGN 162
CombinedgradationisplottedandpushedtowardsIdealcurve
byincreasingordecreasingthesandcontent

163. CONCRETE MIX DESIGN 163
Calculation Of Cement Content
Plastic Density =
(1xSc+1.45xSfa+0.75xSca10+1.6xSca20+w/c)x1000x(1−Ea)
5.26
Sc= Specific gravity of cement
Sfa=Specific gravity of fine aggregate
Sca10=Specific gravity of 10mm coarse aggregate
Sca20=Specific gravity of 20mm coarse aggregate
W/c = water to cement ratio
Ea= Entrapped air %
CementContent(Kg/m3)=Plasticdensity/(1+a/cratio+w/cratio)
Ifweightofcementis“C”thetotalweightperm3willbe
C+1.45C+0.75C+1.6C+0.46C=5.26C

164. Drawbacks Of Road Note No. 4 Method
Thismethodleadstoveryhighcementcontentsandthusisbecoming
obsolete.
Inmanycasesuseofgapgradedaggregatebecomesunavoidable.Inmany
partsofthecountrythepracticeistouse20mmcoarseaggregateswithout
10mmaggregates.Thisisbecauseofqualityof10mmaggregatesproduced
fromjawcrusherisverypoor.Gapgradingdoesnotfitintothestandard
combinedgradingcurvesofRRLmethod.
Sandavailableinsomepartsofcountryisgradedthatitishighoncoarse
fraction(1.18mmandabove)andlowonfines(600micronandbelow).It
isdifficulttoadjustthesandcontenttomatchanyofthestandard
combinedgradingcurves.Thecombinedgradingcurveoftencutsacross
morethanonestandardcurvesinsuchcases
CONCRETE MIX DESIGN 164

165. Differentaggregatetocementratiosaregivenfor
differentlevelsofworkabilityrangingfromlowto
high.Buttheselevelsofworkabilityarenotdefined
intermsofslump,compactionfactororVeeBeetime
asincaseofothermethods.
Thefineaggregatecontentcannotbeadjustedfor
differentcementcontents.Hencetherichermixes
andleanermixesmayhavesamesandproportion,
foragivensetofmaterials.
CONCRETE MIX DESIGN 165

166. References
•Concrete Technology by: R.P. Rethaliya
•Concrete Technology by . M.S. Shetty
•Internet websites
•http://www.foundationsakc.org/

167. Thanks…
CONCRETE MIX DESIGN