Properties of biocemented, basalt-fibre-reinforced calcareous sand

Basalt fibres and biocement were used to improve the mechanical properties of calcareous sand. The biocement was produced through a microbial-induced calcium carbonate precipitation (MICP) process. The unconfined compressive strength (UCS), tensile strength and permeability of the biocemented and fibre-reinforced calcareous sand were evaluated. The calcium carbonate content of each sample was also measured. The microstructure of the biocemented calcareous sand was observed using scanning electron microscopy (SEM). The SEM results indicated that the fibre facilitated the MICP process by bridging the pores in the calcareous sand. As a result, the fibre reduced the brittleness and increased the failure strains of the biocemented calcareous sand. Compared with biocemented calcareous sand without fibre, for all fibre lengths except 4 mm, the UCS, tensile strength and calcium carbonate content of the biocemented calcareous sand increased gradually with an increase in fibre content up to a fibre content of 1%; the optimum fibre content and fibre length were found to be 1% and 8 mm, respectively. The UCS and tensile strength of the biocemented calcareous sand at the optimum fibre content and fibre length increased by 717% and 115%, respectively.