The influence of curing time on properties of the sand columns cemented by bio-barium phosphate

Loose quartz sand grains can well be cemented by microbially-induced barium phosphate precipitation into a sand column. The bio-barium phosphate slurry was composed mainly of BaHPO4, and this was assessed through X-ray diffraction (XRD) analysis. The average compressive strength of sand columns increases with curing time, and increases when the content of bio-phosphate slurry is 20% and 30%wt. The results suggest the best curing time is 7 days, and the optimum content of bio-barium phosphate is 30%wt. Scanning electron microscopy (SEM) images of the sand columns showed the morphology of the cementation products is block, dumbbell-shaped, and spherical, and the products' particles can continue to grow in wet-dry circulation conditions. The sand columns (ϕ5 cm × 5 cm) could be cemented by bio-BaHPO4, and its average strength was 0.6 Mpa. The consolidation layer of dust grains was formed after spraying 1 time and 3 times of bio-BaHPO4 cement, and wind erosion rate of dust was 5 g/m2/h and 0 g/m2/h, respectively. The mixture of NaBaPO4 and Ba5(PO4)3OH under different time was selected and applied to bind loose sand particles, results indicating it could not glue loose sand grains.