To assess the possibility of promotion of fresh medium to resuspend thallus (RF) in sand reinforcement and its mechanisms

a series of solution and sand column tests were conducted to analyze the abilities of four biological solutions with different compositions in urea hydrolysis

MICP

and sand reinforcement. Results show that the ability of the original bacterial solution (US) without any treatment after the completion of culture in urea hydrolysis and MICP mainly derived from the urease in thallus

and the other part came from the free urease released by lysis of bacteria. With high concentration of bacterial solution

the resuspension of thallus by fresh medium could promote the MICP ability of thallus of the biological solution to some extent

however

the removal of supernate (SS) in preparing RF led to urease loss

which resulted in the total MICP ability of RF basically the same with that of the original bacterial solution. The sand column reinforced by original bacterial solution had more calcium carbonate precipitation and higher shear strength

and the co-existence of SS and thallus led to more effective cementation contact. Compared with RF

US has the characteristics of simple

low cost

and high activity

which can be preferred selected in the application of MICP in solving the foundation problem that requires rapid reinforcement.