DETERMINATION ON PORE STRUCTURE OF MICROBIAL INDUCED MINERALIZATION MATERIALS IN SALT ENVIRONMENT BY NMR
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摘要: 微生物矿化岩土材料是利用微生物新陈代谢中的矿化行为来诱导生成碳酸钙沉淀,填充岩土材料孔隙、胶结基质颗粒而形成的一种类岩石的新型绿色土工材料。通过核磁共振方法得到了不同类型溶液环境下不同干湿循环周期后材料的孔径分布曲线, 分析了不同大小孔径的变化与孔隙度之间的联系,研究了这种材料在盐环境下经历多次干湿循环后微观孔结构的变化规律。研究结果表明:当盐蚀和干湿作用共同作用时,材料会发生破坏,表现为颗粒剥落和流失,且复合盐的情况会加剧这种破坏。矿化材料在经历盐蚀-干湿作用侵蚀的过程中,孔隙度与材料破坏剥落的程度相关,并且内部不同孔隙的孔径分布量随着循环周期的增加持续变化,矿化材料中大孔(100~1 000 μm)的孔径分布量最多,且随着循环周期的增加而不断增多;微孔(<1 μm)的累积变化与表征材料破坏程度的孔隙度呈显著相关性。研究成果从微观孔隙结构变化的角度,为微生物矿化岩土材料在盐环境的工程应用提供了参考依据。
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关键词:
- 微生物诱导碳酸钙沉淀 /
- 微生物岩土固化材料 /
- 盐蚀-干湿循环 /
- 低磁场核磁共振 /
- 孔隙分析
Abstract: 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. -
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