Strength durability of gellan gum biopolymer-treated Korean sand with cyclic wetting and drying

•Strength durability of gellan gum biopolymer is verified in this study.•Wetting and drying cycles are performed on gellan gum-treated sand.•Unconfined compressive strength was measured with cyclic wetting and drying.•Gellan gum-treated sand shows hysteretic strength path along wetting-drying cycles.•Dry strength remains 80% even after severe wetting-drying cycles. Various biological approaches recently have been explored as alternative environmentally-friendly soil improvement strategies in the fields of construction and geotechnical engineering, with the aim of reducing the use of high greenhouse gas emitting construction binders such as cement. Previous studies have shown the effectiveness of microbial biopolymers in soil improvement. However, there are still concerns about the durability and serviceability of biopolymer treated soils, resulting from the biodegradation and hydrolysis behaviors of the biologically produced compounds. In this study, the strength and durability of gellan gum biopolymer treated Jumunjin sand (standard sand of the Republic of Korea) was evaluated under cyclic wetting and drying. The results obtained indicate that the cyclic wetting and drying of gellan gum-treated sands results in a gradual degradation of strength, due to the dissociation of the gellan gum monomers under wetting and imperfect recomposition during re-drying, with an approximately 30% strength reduction over 10 cycles. However, a certain degree of strength recovery and resistance was observed even after numerous cycles, indicating that gellan gum-treated soils can potentially be applied for temporary or medium-term purposes in practical construction.