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Soil and compactionSoil and compaction

NurNur HidayahHidayah btbt AbuAbu SafianSafianNurNur HashimawaniHashimawani btbt SaadSaad

NoorNoor HidayuHidayu btbt AmranAmran

SuzeanniSuzeanni btbt JalilJalil

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Introduction of SoilIntroduction of Soil

Soil is formed in place or deposited by various forces ofSoil is formed in place or deposited by various forces ofnaturenature -- such as glaciers, wind, lakes and riverssuch as glaciers, wind, lakes and rivers --residually or organically.residually or organically. Following are importantFollowing are importantelements in soil compaction:elements in soil compaction: -- Soil typeSoil type-- Soil moisture contentSoil moisture content-- Compaction effort requiredCompaction effort required

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Cohesive soilsCohesive soils

Cohesive soilshave the smallest particles.Cohesive soilshave the smallest particles. Clay hasa particleClay hasa particlesize range of .00004" to .002".size range of .00004" to .002". Silt ranges from .0002" toSilt ranges from .0002" to.003"..003". Clay isused in embankment fillsand retaining pondClay isused in embankment fillsand retaining pondbedsbeds..

CharacteristicsCharacteristicsCohesive soilsare dense and tightly bound together byCohesive soilsare dense and tightly bound together bymolecular attraction.molecular attraction. They are plastic when wet and canThey are plastic when wet and canbe molded, but become very hard when dry.be molded, but become very hard when dry. ProperProperwater content, evenly distributed, iscritical for properwater content, evenly distributed, iscritical for proper

compaction.compaction. Cohesive soilsusually require a force suchCohesive soilsusually require a force suchasimpactor pressure.asimpactor pressure. Silthasa noticeably lowerSilthasa noticeably lowercohesion than clay.cohesion than clay. However, siltisstillheavily reliantHowever, siltisstillheavily relianton water content.on water content.

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GranularsoilsGranularsoils

Granularsoilsrange inparticle size from .003" toGranularsoilsrange inparticle size from .003" to.08" (sand) and .08" to1.0" (fine tomedium.08" (sand) and .08" to1.0" (fine tomedium

gra

vel).gra

vel).Granu

lar

soilsar

e know

nfor

their

waterGranu

lar

soilsar

e know

nfor

their

water--draining properties.draining properties.

CharacteristicsCharacteristicsSand and gravelobtainmaximum density ineitheraSand and gravelobtainmaximum density ineithera

fully d

ry o

rsatura

ted state.f

ully d

ry o

rsatura

ted state. Testi

ng c

urves

areTesti

ng c

urves

arerelatively flatsodensity canbe obtained regardlessrelatively flatsodensity canbe obtained regardless

of water content.of water content.

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EffectofMoistureEffectofMoisture

The response ofsoil tomoisture isvery important, asThe response ofsoil tomoisture isvery important, asthe soil mustcarry the load yearthe soil mustcarry the load year--round.round.

RainRain, for

example, may t

ransfo

rm soil intoa plasticstate, fo

rexample, may t

ransfo

rm soil intoa plasticstateoreven intoa liquid.oreven intoa liquid.

In thisstate, soil hasvery little orno loadIn thisstate, soil hasvery little orno load--bearingbearingability.ability.

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Problem ofsoilProblem ofsoil The construction willnotstable ifthe soilisnot compactThe construction willnotstable ifthe soilisnot compact

because the contentofsoilhasa lotofairparticles.because the contentofsoilhasa lotofairparticles.

Thisproblemwill the effect the stability ofsoilandThisproblemwill the effect the stability ofsoilandcollapse the construction.collapse the construction.

In highway engineering, the compaction isneed inIn highway engineering, the compaction isneed insubgradesubgrade construction toincrease the hardnessofsoil.construction toincrease the hardnessofsoil.

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HOWTOSOLVETHEPROBLEMHOWTOSOLVETHEPROBLEM

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SOILCOMPACTIONSOILCOMPACTION

Soil compaction is defined as the method ofSoil compaction is defined as the method ofmechanically increasing the density of soil.mechanically increasing the density of soil. InInconstruction, this is a significant part of the buildingconstruction, this is a significant part of the buildingprocess.process. If performed improperly, settlement of the soilIf performed improperly, settlement of the soil

could occur and result in unnecessary maintenance costscould occur and result in unnecessary maintenance costsor structure failure.or structure failure. Almost all types of building sitesAlmost all types of building sitesand construction projects utilize mechanical compactionand construction projects utilize mechanical compactiontechniques.techniques.

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WhyCompact?WhyCompact?

ThereThere are five principle reasons tocompactare five principle reasons tocompactsoil:soil: --IncreasesIncreases loadload--bearing capacitybearing capacity

-- Prevents soil settlementand frostd

amagePrevents soil settlement

and frostd

amage-- Provides stabilityProvides stability

-- Reduces water seepage, swelling and contractionReduces water seepage, swelling and contraction-- Reduces settling of soilReduces settling of soil

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TypesofCompactionTypesofCompaction

There are four typesofcompaction effortonsoil orThere are four typesofcompaction effortonsoil orasphalt:asphalt:

Vibratio

nVibr

atio

n

ImpactImpact KneadingKneading PressurePressure

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ResultsofPoorCompactionResultsofPoorCompaction

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Why Test?Why Test?

Soil testing accomplishes the following:Soil testing accomplishes the following: Measures density of soil for comparing the degree ofMeasures density of soil for comparing the degree of

compaction vs. specscompaction vs. specs Measures the effect of moisture on soil density vs. specsMeasures the effect of moisture on soil density vs. specs Provides a moisture density curve identifying optimumProvides a moisture density curve identifying optimum

moisturemoisture

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TypesofTestsTypesofTests

ProctorTestProctorTest

A small soil sample istakenA small soil sample istakenfrom thefrom the jobsite.jobsite. A standardA standardweight isdropped severalweight isdropped several

timeson the soil. The materialtimeson the soil. The materialweighed and then oven driedweighed and then oven driedfor12 hours in ordertofor12 hours in ordertoevaluate watercontentevaluate watercontent

Modified ProctorTestModified ProctorTest

This issimilartothe ProctorThis issimilartothe ProctorTestexcepta hammer isusedTestexcepta hammer isused

tocompactmaterial fo

rgreate

rtocompactmate

rial fo

rgreate

rimpact, The test isnormallyimpact, The test isnormally

preferred in testing materialspreferred in testing materialsforhigherforhighershearingshearing strengthstrength..

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CompactionEquipmentCompactionEquipment