Flexural fatigue behavior of fly ash geopolymer stabilized-geogrid reinforced RAP bases

Abstract

Flexural fatigue behavior under heavy traffic loading has been identified as a critical distress problem in a flexible pavement that consists of cemented base/subbase layers. The stresses from repetitive traffic loads eventually reduce the tensile stiffness of the cemented base layer leading to fatigue failure. Therefore, this present study focused on evaluating the flexural fatigue behavior of a high percent (60%) Reclaimed Asphalt Pavement (RAP) replaced by Virgin Aggregate (VA) stabilized with alkali-activated fly ash (FA) under stress-controlled mode. Based on the Unconfined Compressive Strength (UCS), and Repeated Load Triaxial (RLT) test results, a potential design mix was proposed and implemented throughout the testing program. Beam specimens reinforced with biaxial and triaxial geogrids were also experimentally examined for comparison, and the fatigue life of the corresponding specimens was shown to improve by 1.66 and 2.54 times, respectively than the control mix. The fracture energy (GD) and the tensile stiffness index (IRT) of the tested specimens were also evaluated from the flexural strength test results. The test findings indicated that the inclusion of geogrid reinforcement adequately improved the flexural strength and fatigue life of the alkali-activated FA treated RAP:VA beam specimens.