Dynamic cone penetration test - IRC SP 72

It is used for determination of site CBR value of under laying layers without disturbing the strata. A standrad cone of 20 mm dia and angle of 60 degree is penetrated into sub layers and 8 kg hammer is dropped from fall of 575 mm The dia of rod attached to cone is 16 mm. Basically penetration in mm is inversely proportional to strength of material. Thus higher CBR = minimum penetration/no of blows. Max to 1.2 mtr depth the strength/CBR can be checked by DCPT.
It is used in road pavements, after 30-40 uses the cone has to be replaced.

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