Improved fatigue properties of cement-stabilized recycled materials – Lateritic soil using natural rubber latex for sustainable pavement applications

This research project investigates the role of a new recycled pavement material and natural rubber latex (NRL), in improving the resilient and fatigue performances of cement-stabilized recycled materials and lateritic soil (LS) blends under traffic loads. Two types of recycled materials, being steel slag (SS) and recycled concrete aggregate (RCA) and 5% cement content by weight were studied in this research. The dry rubber content in NRL to cement (r/c) ratios of 0%, 3%, 5%, 10%, and 15% were designed as the influence factor. The results indicated that mechanical strength properties namely unconfined compressive strength (UCS) and indirect tensile test (ITS), as well as fatigue properties namely indirect tensile resilient modulus (IT Mr) and indirect tensile fatigue (ITF) were enhanced with the NRL additive. Beyond the optimum r/c ratio, the excessive amount of NRL generated thick NRL films and retarded the cement hydration products, resulting in low strength and performance improvement. The r/c ratios of 3% and 5% were found to be the optimum r/c ratios for cement-NRL stabilized SS:LS and RCA:LS blends, respectively. The brittleness and permanent deformation of cement-stabilized SS/RCA:LS blends were significantly improved by the NRL additive. The superior mechanical and physical properties of SS and RCA were also attributed to the enhancement of fatigue characteristics of the cement-NRL stabilized blends. Finally, the mechanistic and fatigue models of cement- and cement-NRL stabilized soil with recycled material replacements were proposed, which are important for pavement designers and engineers when using a mechanistic-empirical pavement design approach.