Pavement Premature Failure on a Moisture Susceptible Base

A forensic investigation was conducted to determine the underlying cause of a premature pavement failure. The premature pavement failure was occurred in the form of rutting and alligator cracking. Through extensive field and lab testing, it was found that the moisture susceptible base is the primary cause of the premature failure and the porous asphalt concrete (AC) being the secondary cause. It is noted that the base layer was built according to plan and met the current material and field density requirements. As part of the field investigation, ground penetration radar (GPR) was utilized to survey the entire area. AC cores were taken to correlate the dielectric measurements from GPR with the lab measured density to generate the density/air-void map. More than 50 cores were taken to accurately determine the air void content. The results indicate that the air void exceeds 10% and did not meet the specification requirements. Based on the lab results, there are 36% of the cores fall into the category of either penalty or remove and replace. It was concluded that material requirements which are only based on the field density and moisture content are inadequate to control the construction quality, as it was not able to protect against premature failures illustrated in this paper from occurring. Even though it is tedious to conduct the moisture susceptibility tests to determine strengths at different moisture levels, it is a viable tool to minimize the premature pavement failures.