Micro-experiment on MICP-treated Aeolian sandy soil under ultraviolet erosion environment

Based on the MICP technology and the aeolian sandy soil of Ulan Buh desert as geotechnical substrate materials, the ultraviolet erosion characteristics of mineralization aeolian sandy soil induced by MICP are studied. In addition, the total effective time of outdoor ultraviolet irradiation in winter in Ulan Buh desert area is equal to the total effective time of indoor ultraviolet irradiation, and the ultraviolet irradiation time of indoor UV-erosion tests is determined. Through the scanning electron microscopyand nuclear magnetic resonance technology, the pore characteristics of the mineralization samples are analyzed with the irradiation period under the same ultraviolet radiation intensity. The results show that after UV-erosion, the microscopic electron microscope scanning indicates the that the MICP-mineralized specimen has pores in the calcium carbonate crystal under the ultraviolet erosion for a long time, which proves that the long-term irradiation erosion of ultraviolet weakens the property of calcium carbonate. When the ultraviolet erosion time is 1046 h, the porosity rate of MICP-mineralized aeolian sandy soil is 23.6%. In the nuclear magnetic resonance (NMR) tests, the T₂ spectra of the specimens before ultraviolet erosion have multiple peaks and the pore distribution is uneven. The porosity of the specimen increases with the increase of irradiation time. With the increase of irradiation time, the pores are developed and expanded constantly, the large pores were decrease and the medium-sized pores increase. However, the small pores gradually develop and connect with the medium-sized ones, although there are residual macropores, most of them are converted into medium-sized ones, and the ultraviolet erosion resistance of mineralization materials gradually decreases. The pores of the three specimens are mostly distributed in the range of 0.1~8 μm, and the radius of small pores is mainly 1 μm. The study of ultraviolet erosionof bio-mineralization Aeolian sandy soil in the laboratory may provide a basic researchand favorable experimental basis for the application of this technique in the in-situ microbial crust of desert.