Significance of Effective CBR in the Design of Flexible Pavement

In this paper, the effective California Bearing Ratio (CBR) on design for flexible pavement is discussed. The design strength in CBR of the pavement layers is very much dependent on the strength of the subgrade soil. The weaker subgrade requires a higher thickness of the pavement layer and vice versa. The embankment soil at the top level is more compact as compared to the subgrade soils. If the top layer needs to be compacted to a thickness of 500 mm/300 mm from the borrowed materials of suitable quality. IRC: 37-2012 suggests the use of effective CBR for the design of pavements considering the strength of the existing soils. Moreover, if the soil CBR of the subgrades is high, the effective CBR also becomes higher. CBR is the most adopted method to find the strength of soil subgrades.