Mechanical Strength Improvement of Cement-Stabilized Soil Using Natural Rubber Latex for Pavement Base Applications

Abstract

Thailand is an agricultural country, ranked as the top in the world for the production and export of natural rubber. This study investigated the influence of natural rubber latex (NRL) replacement on the mechanical strength improvement of cement-stabilized soil. Cement contents of 3%, 5%, and 7% by weight of dry soil and NRL replacement ratios of 10%, 15%, 20%, 25%, and 30% by weight of compacting water were used in this research study. The mechanical strengths were investigated via unconfined compressive strength (UCS) and flexural strength (FS) tests. The mechanical strengths improvements were examined through scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses. NRL replacement was found to significantly enhance the mechanical strengths of cement-NRL stabilized soil. The optimum NRL replacement ratios providing the highest density, compression, and flexural strengths were found at 20%, 15%, and 10% for 3%, 5%, and 7% cement contents, respectively. At the optimum NRL replacement ratio, the UCS was improved up to 30%, 21%, and 18% for 3%, 5%, and 7% cement contents. While, FS was improved up to 78%, 40%, and 29% for 3%, 5%, and 7% cement contents. Even though the NRL films within the soil-cement matrix improved the cohesion of the soil matrix, it was found to retard cementation bonding. As such, the excessive NRL replacement not only reduced the compactability but also retarded the cement hydration and, hence, the strength reduction. The outcome of this research will promote the usage of NRL as a sustainable alternative to imported synthetic latexes for improving the mechanical strength of cement-stabilized soil for pavement bases.