New method for using N-(N-butyl)-thiophosphoric triamide to improve the effect of microbial induced carbonate precipitation

Intensive studies have been carried out to establish a soil improvement method based on the microbial induced carbonate precipitation (MICP) process. However, controlling the reaction rate of the MICP process to achieve optimized improvement is still a challenging task. In this paper, a new method involving use of urease inhibitor N-butyl-thiophosphoric triamide (NBPT) was introduced. Laboratory tests in both liquids and soils showed that use of a suitable amount of NBPT increased the amount of calcium carbonate precipitation and improved the mechanical properties of the soil. Scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) and X-ray diffraction (XRD) were also used to understand the effects of NBPT on calcium carbonate precipitation. The suitable dosage of NBPT was identified and the mechanisms behind the effect of NBPT were explained in this paper.