Based on MICP technology

the loose sandy soil was improved into microbial mineralized material.The changing rules of freeze-thaw properties of microbial mineralization materials

such as the apparent morphology

mass loss ratio

saturated water content

and unconfined compressive strength

with freezing and thawing cycles were studied through indoor freeze-thaw cycles experiment.Four different freeze-thaw solutions were used in this study.The results show that mineralized material appears spalling phenomenon in aqueous solution and salt solution with the increase of freeze-thaw cycles.Unconfined compressive strength decreases in the whole process of experiment.The loss of mass and the increase of saturated water content heavily affect the anti-frost properties of material.In 5% Na2 SO4 solution

mineralization material’s pulverization rate is faster and the quality loss rate is the largest

the damage is the fastest and most serious;in the NMR spectrum

when the relaxation time is longer than 200 ms

the change of the unfrozen water content is the largest in the freeze-thaw process

which is the main reason for the loss of the quality of the specimens and the destruction of the strength.The frost resistance of the specimens in the deionized aqueous solution is also weaker than in Na2 SO4 solution.The freezing point of the mineralization material reduces and the freezing resistance prolongs due to the presence of NaCl in the 3% NaCl solution and the mixed solution.This research provides basic experimental evidence for the engineering application of microbial mineralized material in cold regions.