CBR VALUE OF SANDY SUBGRADE BLENDED WITH COARSE AGGREGATE

Abstract

In several parts of India, soil deposits consist of a matrix like soil with inclusions of coarser
aggregates of various sizes. The CBR test is used for the design of sub grade for highways & pavement.
Therefore in the present investigation, the CBR tests were carried out on the sand blended with coarse
aggregates of various sizes and proportions. To strengthen the sub grade strata, coarse aggregates of 10mm and
20mm sizes were mixed in the sand, in various proportions. The soil samples were prepared and tested first
without coarse aggregates, then by mixing coarse aggregates in varying percentages by weight, starting from 5%
to 30%. The results of CBR tests shows that with the increase in the percentage of coarse aggregates, the CBR
value of the soil increases. It is observed that the percentage improvements in the CBR values ranges from 20.99
% to 115.83% and 31.30% to 151.94% for 10mm and 20mm coarse aggregates respectively at OMC. In soaked
condition, this improvement ranges from 23.20% to 202.48% and 31.35% to 233.17% for 10mm and 20mm
coarse aggregates respectively.