Long-Term Pavement Structural & Functional Evaluation on State Route 76

MDOT funded the construction of an instrumented semi-rigid pavement test section at the National Center for Asphalt Technology (NCAT) test track. An unexpected but interesting finding was observed in strain gage readings located at the interface between the hot mix asphalt (HMA) and the cementitious stabilized base (CTB) layer: during hot summer months, compressive strain measurements were recorded under truck traffic loading, contrary to expected tensile strain measurements. NCAT described these findings in a TRB paper that help to explain in part why some MDOT semi-rigid pavement sections may experience fatigue cracking originating at the mid-depth of the HMA rather than at the typical bottom of HMA location for this type of cracking. MDOT is further investigating the phenomenon observed in the MDOT NCAT structural section by building a test section in Mississippi, specifically located on SR 76 in District 1. NCAT will install strain gages and monitor the same. Pavement structural and functional evaluation using non-destructive testing on the SR 76 test section is needed to accurately monitor pavement condition and deterioration rate of pavement layers with time. Pavement performance monitoring will be accomplished using Applied Research Associates, Inc. (Consultant) testing equipment including the three dimensional (3-D) Ground Penetration Radar (GPR), Falling Weight Deflectometer (FWD) and the state-of-the-art high accuracy GPS semi-automated pavement distress survey vehicle equipped with the Laser Crack Measurement System (LCMS). This State Study (SS) will focus on data collection and analysis to monitor the reduction in modulus of both the cementitious stabilized soil base layer and HMA layers, and development of distresses within the pavement structure from the time of new construction up to three (3) years after opening to traffic.