A Correlation Between Dynamic Cone Penetrometer Values and Pavement Layer Moduli

Abstract

The Dynamic Cone Penetrometer (DCP) is one of the least expensive testing devices able to characterize base and subgrade properties. To fully use the DCP in pavement evaluation, an empirical relationship between DCP penetration rate and layer modulus is required. However, the literature on this correlation is limited. This study incorporates a total of 198 DCP and Falling Weight Deflectometer (FWD) tests done over 8 years on various types of highways (Interstate Highway, US, and Farm-to-Market). The computer program MODULUS was employed to backcalculate the layer moduli from the FWD results to build a correlation with DCP results. A comparison was made with the widely-used model by Powell et al. (1984). It is found that the difference between the two models decreases as the Penetration Rate (PR) increases. For a PR of less than 10 mm/blow, the difference between these two models was over 10%. The difference is only about 1.7 % when the PR is 80 mm/blow. Without knowing the true moduli, it is impossible to tell which equation is better. The correlation developed here provides another option and allows researchers to recognize the range of variability.