New Look at DCP Test with a Link to AASHTO SN Concept

Abstract

The dynamic cone penetration (DCP) test has emerged as a simple but effective tool for characterizing granular pavement materials and subgrades. However, DCP data tend to be used more in the converted form, e.g., as California bearing ratio (CBR) or resilient modulus (MR) based on correlations, than on their own and are also perceived as highly variable. This paper looks into the data error and variability aspects and concludes that with reasonable care taken to control testing errors, DCP data can be treated as representative of in situ materials characteristics. The paper brings out an analogy between DCP blow rate (blow/mm penetration) for a pavement layer and the corresponding AASHTO layer coefficient. It is further shown that the DCP number (DCPN), cumulative blows required to penetrate through the pavement structure, is analogous to the AASHTO structural number (SN) as an expression of pavement structural capacity. These findings would facilitate the direct use of DCP data within AASHTO pavement design framework.