Exp 1 Flakiness and Elongation Index

3/9/2015 Exp1FlakinessandElongationIndexCivilEngineersPK

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Exp1FlakinessandElongationIndexFlakinessandElongationIndexEXPERIMENTNO.1:Determinationoftheflakinessandtheelongationindexforthegivenaggregate.sample.SCOPE&SIGNIFICANCE:

This test is used to determine the particle shape of the aggregate and each particle shape beingpreferredunderspecificconditions.

Thesignificanceofflakiness&elongationindexisasfollows

Thedegreeofpackingoftheparticlesofonesizedependsupontheirshape.Duetohighsurfaceareatovolumeratio,theflakyandelongatedparticleslowertheworkabilityofconcretemixes.Flakyandelongatedparticlesareconsideredundesirableforbasecoarseconstructionastheymaycauseweaknesswithpossibilitiesofbrakingdownunderheavyloads.BS1241specifiesaFlakinessindexnotexceeding30%irrespectiveoftheaggregatesize.MaximumpermittedElongatedindexis35,40or45%foraggregatesizes22,1&

3/8.BothFlakinessandElongationtestsarenotapplicabletosizessmallerthen6.3mmi.e.sieve.

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3/9/2015 Exp1FlakinessandElongationIndexCivilEngineersPK

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RELATEDTHEORY:

SHAPESOFPARTICLES

Theusualshapesoftheparticlesare

1. Rounded(rivergravel)2. Flaky(laminatedrock)3. Elongated4. Angular(crushedrock)

PREFERREDUSEOFEACHSHAPE

Roundedaggregatesare preferred inconcrete roads (rigid pavements) asthe workability of concrete increasesdue to the less friction between thesurfaces.

Angular shapeof the particles isdesirableingranularbasecoarse(flexiblepavement)duetobetterinterlockingandincreasedstability.

FlakyandElongatedparticlesareconsideredasasourceofweakness.

APPARATUS:

Thickness/FlakinessIndexGaugeLength/ElongationIndexGaugeAggregatesampletobetested

FLAKY

A flaky particle is the one whose leastdimension (thickness) is than 0.6 timesthemeansize.

http://civilengineerspk.com/wp-content/uploads/2014/04/images.jpghttp://civilengineerspk.com/wp-content/uploads/2014/04/H-16841.jpg

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These are the materials of which thethickness is small as compared to theothertwodimensions.Limit of flaky particles in the mixes is30%.Iftheflakyparticlesaregreaterthan30% then the aggregate is consideredundesirablefortheintendeduse.

FLAKINESSINDEX

Itisthepercentagebyweightofflakyparticlesinasample.

Procedure

PerformthesieveanalysisonthegivenaggregatesampleTheaggregatesarethenarrangedintheintoanumberofcloselylimitedparticlesizegroupsstoredortedonthetestsievesintoanumberofcloselylimitedparticlesizegroups22,1&3/8

Eachgroup(fraction) isweighedandtested forthicknessonappropriateopening ofthethicknessgaugebypassingeachparticlethroughslotofspecifiedthicknessalongleastdimension.Theweightofparticlespassingthethicknessgaugeisrecordedforeachfraction.Thisistheweightofflakyparticles.Theflakinessindexiscalculatedbyexpressingtheweightofflakyparticlesasapercentageoftotalweightofthesample.

CalculationforFlakyParticles:

SieveSize WeightRetained

PercentageRetained

WeightofFlakyParticles

IndividualFlakinessIndex

WeightedFlakinessIndex

Passing Retained (gm) (%) (gm) (%) (%)

(in.) (in.)

2 1 2007.8 22.52 80.5 4.01 0.9

1 1 2926.4 32.83 853.1 29.15 9.6

1 2177.7 24.43 585.6 26.89 6.57

1076.2 12.07 291.7 27.1 3.27

8Mar 460.2 5.16 155.5 33.79 1.74

8Mar 211.8 2.38 88.3 41.69 0.99

Pan 53.4 0.6

3/9/2015 Exp1FlakinessandElongationIndexCivilEngineersPK

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=8913.5 =23.07

ELONGATEDPARTICLES

These arethe particles havinglength considerablylarger than theother two dimensionsand itis theparticlewhosegreaterdimensionis1.8timesitsmeansize.

Limitofelongatedparticlesinthemixesis45%.Thus,iftheelongatedparticlesaregreaterthan45%,thentheaggregateisconsideredundesirablefortheintendeduse.

ELONGATIONINDEX

It isthepercentagebyweightofelongatedparticlesinasample.TheElongatedindexiscalculatedbyexpressingtheweightofElongatedparticlesaspercentageoftotalweightofthesample.

CalculationforElongatedParticles:

SieveSize WeightRetained(gm)

PercentageRetained

WeightofElongatedParticles

IndividualElongationIndex

WeightedElongationIndex

Passing Retained (%) (gm) (%) (%)

(in.) (in.)

2 1 2007.8 22.52 1561.5 77.77 17.52

1 1 2926.4 32.83 950 32.46 10.66

1 2177.7 24.43 1113.8 51.15 12.5

1076.2 12.07 467.5 43.44 5.24

41341 460.2 5.16 185.5 40.31 2.08

41341 211.8 2.38 80.9 38.2 0.91

Pan 53.4 0.6

=8913.5 =48.91

PRECAUTIONS:

1. Whilesieving,caremustbetakenthattheparticlesthatarechockedinthesievemustnobeforceddownintothenextsieve.Suchparticlesshouldbepushedbackintothesamesieve.

2. While placing different fractions on the table, place them some distance apart so that no two

3/9/2015 Exp1FlakinessandElongationIndexCivilEngineersPK

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9thoughtsonEXP1FLAKINESSANDELONGATIONINDEX

2. While placing different fractions on the table, place them some distance apart so that no twofractionsmaygetmixed.

3. Be careful while selecting the opening of the flakiness and elongation gauges for any particularfraction.FlakinessandElongationIndexFlakinessandElongationIndex

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onJuly10,2014at20:21said:

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CivilEngineersPK

onJuly28,2014at12:38said:

Thanks

Razakhussain

onJuly28,2014at12:18said:

Flanknessandelongationformula

CivilEngineersPK

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onJuly28,2014at12:39said:

Theabovegaugesareusedtoseparatethem

MindFreak

onNovember29,2014at11:36said:

AOA!howmuchsamplehaveyoutakenforthisexperiment?

eldaiab

onDecember23,2014at08:21said:

thelimitsgivenforflakinessandelongationareapplicableforalltypeofroads?

UBAIDAHMAD

onDecember24,2014at09:42said:

pleaseseethecodesforthat

sanjay

onJanuary13,2015at17:42said:

Pleaseprovideexcelcalculationsformat

UBAIDAHMAD

onJanuary14,2015at19:17said:

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