Prueba Cbr

7/27/2019 Prueba Cbr

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Normally 3 specimens each of about 7 kg must be compacted so that their

compacted densities range from 95% to 100% generally with 10, 30 and 65 blows.

Weigh of empty mould

Add water to the first specimen (compact it in five layer by giving 10 blows per

layer)

After compaction, remove the collar and level the surface.

Take sample for determination of moisture content.

Weight of mould + compacted specimen.

Place the mold in the soaking tank for four days (ignore this step in case of

unsoaked CBR.


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Take other samples and apply different blows and repeat the whole process.

After four days, measure the swell reading and find %age swell.

Remove the mould from the tank and allow water to drain.

Then place the specimen under the penetration piston and place surcharge

load of 10lb.

Apply the load and note the penetration load values.

Draw the graphs between the penetration (in) and penetration load (in) and

find the value ofCBR.

Draw the graph between the %age CBR and Dry Density, and find CBR at

required degree of compaction.


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1.- Determine the mass of the mould with base

plate attached


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COLOCAR BASE CUADRADA, ESPACIADOR+MOLDE


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Prepare soil sample. Mix the dry soil with water so that the mixture has a

water content that is 1% below the optimum moisture content.

Prepare around 6 kg of mixture. Collect required data on soil properties

and tabulate


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Remove the detachable collar and.


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trim the top of the mould


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RETIRAR MOLDE


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COLOCAR PAPEL FILTRO


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GIRAR MOLDE CON ARENA HACIA EL FILTRO


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GIRAR MOLDE CON ARENA HACIA EL FILTRO


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COLOCAR COLLAR DE EXTENSIN


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COLOCAR DISCO DE CARGA CIRCULAR (O) EN PLATOCON TALLO


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AGREGAR DISCO DE CARGA (C) EN PLATO CON TALLO


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INTRODUCIR PLATO + 2 DISCOS EN MOLDE


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INTRODUCIR MOLDE CON DISCOS EN AGUA


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COLOCAR TRIPIE EN MOLDE


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COLOCAR MANERAL CON VSTAGO DE MICRMETRO


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COLOCAR MANERAL CON BAYONETA DE MICRMETRO


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RETIRAR MOLDE DEL AGUA Y RETIRAR PLATO + DISCOS DE CARGA


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REGISTRAR MASA DEL MOLDE


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COLOCAR DISCO DE CARGA (O) EN MOLDE


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AGRGAR DISCO DE CARGA (C) EN MOLDE


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COLOCAR DISCO ESPACIADOR EN BASE DE MOLDE Y COLOCAR ENPRENSA


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APLICAR CARGA 1.25 mm/min.


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CARGA APLICADA


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RETIRAR SUELO DE MOLDE


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COLOCAR SUELO EN CHAROLA


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COLOCAR CHAROLA EN BSCULA & REGISTRAR MASA


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INTRODUCIR AL HORNO


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Typical CBR Ranges


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General Soil

Type

USC Soil

TypeCBR Range

GW 40 - 80

GP 30 - 60

GM 20 - 60

GC 20 - 40

SW 20 - 40

SP 10-40

SM 10-40

SC 5-20

ML 15 or less

CL LL < 50% 15 or lessOL 5 or less

MH 10 or less

CH LL > 50% 15 or less

OH 5 or less

Coarse-

grained soils

Fine-grained

soils

Typical CBR Ranges


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The harder the surface, the higher the CBR

rating. A CBR of 3 equates to tilled farmland,

a CBR of 4.75 equates to turf or moist clay,

while moist sand may have a CBR of 10. High

quality crushed rock has a CBR over 80. Thestandard material for this test is crushed

California limestone which has a value of

100.


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Prueba Cbr

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