Multi-functional performance of biopolymers and biocement in stabilisation of road bases

To achieve the UN Sustainable Development Goals, Australia must dramatically reduce the use of cement for stabilisation of soil used in road bases. Bio-based binders for soil stabilisation are potential alternatives. Biocementation through microbially induced calcite precipitation (MICP) is well researched. A few research studies on biopolymeric stabilisation are also available. This paper explores the synergistic effect of combined biopolymer and biocement for the stabilisation of sandy soil and road bases. The soil was stabilised using both biopolymer (xanthan gum) and MICP. The synergy between the biopolymer and MICP was evaluated by giving a few samples a combined treatment. The performance was evaluated by compressive strength tests, micrographic analysis and water absorption tests. Although the biopolymer treatment improved the compressive strength, it degraded significantly in the presence of water. The relatively high water absorption of xanthan gum could be mitigated by MICP. The study demonstrates that MICP surface coating is a sustainable solution to overcome this limitation of the biopolymer. Likewise, the addition of biopolymers reduces the release of ammonia from MICP. This study unravels the potential of a composite bio-treatment for the stabilisation of road bases.