Self-Consolidating Concrete - Rheology Fresh Properties and Stru
Concrete Technology Properties of Fresh Concrete
-
Upload
chidi-henry -
Category
Documents
-
view
257 -
download
10
Transcript of Concrete Technology Properties of Fresh Concrete
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
1/37
PropertiesofFreshandHardenedConcrete
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
2/37
PropertiesofFreshConcrete
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
3/37
Workability SlumpLoss
Segregation/Bleeding
PlasticShrinkage
TimeofSet
Temperature
Outline
[email protected] 04/01/2013DepartmentofCivilandEnvironmentalEngineering,UniversityofLagos
3
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
4/37
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
5/37
Workability
Slumtest
CompactingFactor
VBConsistometer
Tests
[email protected] 04/01/2013DepartmentofCivilandEnvironmentalEngineering,UniversityofLagos
5
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
6/37
SlumpTest
Invertedcone
fillitupwiththreelayersofequalvolume
rodeachlayer25timesscrapeoffthesurface
200
100
300
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
7/37
SlumpTest
slumpcone
rod
concrete
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
8/37
Slumptest
Slump
Ruler
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
9/37
TypesofSlump
Collapse Shear True
Inacollapseslumptheconcrete
collapses
completely.
Inashearslumpthetopportionoftheconcrete
shearsoffandslipssideways.
Inatrueslumptheconcretesimplysubsides,keeping
moreorlesstoshape
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
10/37
Europeanclassesofslump
According
to
European
Standard
EN
206
1:2000
five
classesofslumphavebeendesignated,astabulatedbelow
Slump
class Slump
in
mm
S1 10 40
S2 50 90
S3 100 150
S4 160210
S5 220
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
11/37
Factoraffectingworkability
Cementwater
Admixtures
Aggregate
AmbientConditions
Time
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
12/37
Cementwater
Theworkabilityoftheconcretedecreasesasthefinenessofthecementincreases.
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
13/37
Admixtures
Theprincipaladmixtureseffectingimprovementintheworkabilityofconcretearewaterreducingandair
entrainingagents. Workabilityadmixturesareusedtoincrease
workabilitywhilethemixproportionsarekeptconstantsortoreducethewatercontentwhilemaintainingconstantworkability.
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
14/37
Aggregate
Theworkabilityofconcreteismainlyinfluencedbythetotalsurfaceareaoftheaggregate.
Thesurfaceareaisgovernedbythemaximumsize,gradingandshapeoftheaggregate.
Workabilitydecreasesasthespecificsurface
increases..
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
15/37
AmbientConditions
Environmentalfactorsthatmaycauseareductioninworkabilityaretemperature,humidityandwind
velocity
.
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
16/37
Time
Timeofmixingofconcreteanditsfinalcompactiondependsonthegeneralconditionsofworksuchas
thedistancebetweenthemixerandthepointofplacing,siteproceduresandgeneralmanagement.
.
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
17/37
Segregation
Whenthereisasignificanttendencyforthelargeandfineparticlesinamixtobecomeseparated,
segregationissaidtohaveoccurred.i.e.coarseaggregatetendstosegregateduetogravity.Typicalofdrymixes.
.
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
18/37
Bleeding
Wheretheconsistencyofamixissuchthatitisunabletoholdallitswater,someofitisgradually
displacedandrisestothesurface. Typicalofwetmixes.
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
19/37
Bleeding
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
20/37
Causesofbleedingandsegregation
Improperslump
Excessiveamountofcoarseaggregate
Lackoffines
Inappropriateplacingandcompacting
.
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
21/37
ControlofBleeding
Reductionofwater
Introductionoffinesandair
ProperCompaction(toomuchcompaction
causesbleeding).
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
22/37
PropertiesofHardenedConcrete
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
23/37
Outline
Compressivestrength
Tensilestrength
Factoraffectingstrengthofconcrete
Deformation
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
24/37
Compressivestrength
Thecompressivestrengthofconcreteistakenasmaximumcompressiveloaditcancarryperunitarea.
ConcretestructuresarenormallydesignedonthebasisthatconcreteiscapableofresistingONLYcompression,thetensionbeingcarriedbysteelreinforcement.
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
25/37
Tensilestrength
Thetensilestrengthisoneofthebasicandimportantpropertiesoftheconcrete.Theconcreteisnotusually
expectedtoresistthedirecttensionbecauseofitslowtensilestrengthandbrittlenature.However,thedeterminationoftensilestrengthofconcreteisnecessarytodeterminetheloadatwhichthe
concretemembersmaycrack.Thecrackingisaformoftensionfailure.
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
26/37
Tensilestrength
Apartfromtheflexuretesttheothermethodstodeterminethetensilestrengthofconcretecanbebroadlyclassifiedas
(a)directmethods,and
(b)indirectmethods.Thedirectmethodsuffersfromanumberofdifficultiesrelatedtoholdingthespecimenproperlyinthetestingmachinewithoutintroducingstressconcentration,andtothe
applicationofuniaxialtensileloadwhichisfreefromeccentricitytothespecimen
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
27/37
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
28/37
Tensilestrength
Inducedtensilestressatfailureisgivenas
2
=Maximumappliedload
=cylinderlengthanddiameterrespectively
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
29/37
Tensilestrength
Flexuralstrengthofconcreteisanotherindirecttensile.Flexuralstrength(modulusofrupture)isgivenby
=Maximumappliedload
=distancebetweenthesupports
=beambreadthanddepthrespectively
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
30/37
FactorsAffectingStrength
1. Influenceofconstituentmaterials
Cement:finenessandchemicalcomposition
Water:a minimumamountofwaterforaproper
hydrationAggregate:thebond(aggregatematrixinterface)
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
31/37
FactorsAffectingStrength
2. Admixtures
Calciumchlorideisanacceleratoradmixtures,itincreasestherateofdevelopmentofstrengthatearlydays.
3. Methodsofpreparation
4. Influenceofcuring
5. Influenceoftestcondition(Cube,Cylinderandsquareprism)
6. Specimen
moisture
content
and
temperature7. Methodofloading
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
32/37
StrengthandCuring
time
inairentiretime
moistcuredentiretime
inairafter3days
inairafter7days
Strength
28
100%
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
33/37
Deformation
Concretedeformsunderload,thedeformationincreaseswiththeappliedloadelasticdeformation.
Whenitcontinuestodeformwithtimeunderconstantloadtimedependentdeformationorcreep
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
34/37
Elasticdeformation
Deformationrelationshipforconcretesubjectedtoacontinuousincreasingloadisnonlinearincharacter
Whentheappliedloadisreleasedtheconcretedoesnot
fullyrecovereditsoriginalshape.
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
35/37
Creepdeformation
Concretesubjectedtosustainedloadwillundergoelasticandcontinuestodeformwithtime.
Theincreaseinstrainwithtimeistermedcreep
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
36/37
Shrinkage
Settlementofsolidsandthelossoffreewaterfromtheplasticconcrete,bythechemicalcombinationofcementwithwater(autogenous shrinkage)andbythedryingofconcrete(dryingshrinkage)
PlasticShrinkage:takesplacebeforeconcreteset
Autogenous Shrinkage:ashydrationcontinuesinanenvironmentwherewatercontentisconstant,thereis
a
decrease
in
volume
of
the
cement
paste
which
results
inshrinkageoftheconcrete.
-
8/10/2019 Concrete Technology Properties of Fresh Concrete
37/37
Shrinkage
Dryingshrinkage:waterlosesfromthevoidsandcapillaryporesafterconcretehardened,furthershrinkagewherewaterisdrawnoutofcementgel.