Xanthan Gum Biopolymer as Soil-Stabilization Binder for Road Construction Using Local Soil in Sri Lanka

Currently, soil stabilization is used in road construction in Sri Lanka, especially for soft road shoulders. The socioeconomic demand for sustainable development has raised the necessity of new environmentally friendly soil binders for construction engineering practices, including road construction. Industrial residues such as fly and bottom ashes are commonly used to reduce the amount of cement in concrete mixtures or soil stabilization practices, and new biological materials and methods have been introduced by a number of studies to improve the strength of soils without the use of chemical binders such as cement. Among others, microbial-induced biopolymers have been experimented with as a new binder material for soil treatment due to their high strengthening efficiency and low environmental impact. This study verified the feasibility of biopolymer application on local soil stabilization, specifically for road shoulder construction in Sri Lanka, by comparing the unconfined compressive strength (UCS) of local soil samples treated with cement-ash–based binders and xanthan gum biopolymer. The xanthan gum biopolymer–treated condition had significant UCS strengthening and high ductility compared with other treated conditions. Thus, xanthan gum biopolymer shows promising potential as an alternative material for road construction (particularly for shoulders and subbases) in Sri Lanka and in other nations with similar climates and socioeconomic conditions.