Development of Sampling Procedure for Rigid Pavement Strength Evaluation

Pavement surface deflections measured with Falling Weight Deflectometer (FWD) are used to represent pavement strength and to backcalculate the moduli of pavement layers. Sampling testing is recommended and widely used for network level evaluation. However, there is no specific methodology to conduct sampling evaluation. Based on a pavement rehabilitation project in Sichuan Province, China, two sampling procedures, systematic sampling and cluster sampling, are discussed for rigid pavement strength evaluation. Testing at different intervals from 50 m to 500 m is analyzed. It is verified that the approach recommended in current specification can estimate the true strength. Moreover, it is found that interval distance for pavement strength evaluation at network level can be increased to 500 m. An alternative method based on cluster sampling is capable of evaluating pavement strength at some situations. The development of sampling procedure would provide enough information for engineers to determine the general pavement strength of a pavement network with better cost-effectiveness than that of conventional evaluation approach.