Microbially induced calcium carbonate precipitation is a biomineralization process that has various applications in remediation and restoration of range of applications. In the present study, calcifying bacteria, Bacillus subtilis and Bacillus megaterium isolated from soil (Viet Nam). These species were investigated for sand stiffening using syringe set-up with daily nutrient addition at 7, 14 and 28 days. The stiffened sand samples were tested the physical and chemical properties. The calcium carbonate polymorphs produced by Bacillus subtilis and Bacillus megaterium were analyzed by scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray diffraction (XRD). These results show that both of the Bacillus species could make consolidation through calcite precipitation at the alkaline pH rate of 9, increased impact strength of the stiffened sand samples. Furthermore, isolated B. megaterium shows it is potential as bio-sealant to enhance the durability of low energy, green building materials (soil-cement blocks).