DETERMINATION ON PORE STRUCTURE OF MICROBIAL INDUCED MINERALIZATION MATERIALS IN SALT ENVIRONMENT BY NMR

Microbial mineralized geotechnical materials are new kinds of rock-like green materials, which matrix particles are cemented and pores are filled with calcium carbonate precipitation induced by mineralization properties of microbial metabolism. The curves of pore-size distribution for the material after enduring drying-wetting cycles and corroded by different salt solutions were obtained by NMR, the relationships between the pore size and porosity were analyzed, and the change rule of the micro-pore structure for the material was studied. The results showed that under the combined action of corrosion and dry-wet cycling, the material would be destroyed sooner, which was characterized by spalling and loss of particles, and the damage would be aggravated under the condition of compound salt. During the process of salt corrosion and dry-wet cycling, the porosity of materials was related to the degree of material damage and exfoliation, and the pore-size distribution of different pores in the materials changed continuously with the increase of cycles. The pore-size distribution of macropores (100 to 1 000 μm) was the most and increasing with the increase of cycles. The cumulative changes of micropores (<1 μm) were significantly correlated with the porosity which characterized the degree of material damage. The research results could provide references to the engineering practices of the materials in the salt environment from the perspective of micro-pore structure changes.