微生物水泥胶结砂体的界面及其对性能的影响

发布时间：2018-03-10 10:27

本文选题：微生物水泥　切入点：胶结性能　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：基于微生物诱导沉积矿化的微生物水泥能够固结松散颗粒,且能耗低、污染少,在地基加固、扬尘治理等领域可以解决传统材料的一些弊端,如生产能耗高、化学毒性大等,是一种新型的可持续发展的胶凝材料。目前,生物碳酸钙水泥研究最为广泛,但主要针对其制备与应用方面,而本课题通过筛选、培育出一种适合胶结用的磷酸盐微生物,对特定底物作用并矿化沉积出生物磷酸盐胶凝材料。同时从宏观胶结性能、胶结界面性质以及胶结物质与颗粒间的微观作用等方面对比了生物碳酸盐水泥与生物磷酸盐水泥的差异,并进一步揭示了微生物水泥胶结作用的本质。本文的主要研究成果如下：利用一种磷酸盐矿化微生物,对特定底物作用并矿化合成出生物磷酸盐沉积产物,分析表明产物为羟基磷灰石,微观形貌呈纳米球形颗粒的团聚体。通过溶液体系内生物磷酸盐的沉积条件优化研究,确定了生物磷酸盐基本配方。对比研究不同微生物水泥胶结砂体可知,在砂体强度相近的条件下,生物碳酸钙胶结砂体渗透系数与孔隙率均明显高于其它实验组,而砂体内的胶结物质含量却低于其它实验组,表明单位质量的生物碳酸钙的强度要高于其它微生物水泥。同时,砂体内部微观分析表明,各胶结物质的沉积量与沉积分布方式均存在明显差异。超声振荡脱粘实验结果表明,生物碳酸钙在玻璃片上沉积明显,颗粒分布均匀且与玻璃片的界面结合作用较强,其余依次为生物鸟粪石、生物磷酸钡以及化学碳酸钙,而生物磷酸钙沉积效果最差,划痕实验结果进一步验证了上述规律。由界面结合强度与胶结物质沉积量的关系可知,单位质量的生物碳酸钙的界面结合强度最大,这也与砂体的胶结强度规律吻合。利用X射线光电子能谱和核磁共振分析方法,研究了生物胶结物质与松散砂颗粒间的作用,结果表明：在微生物矿化沉积中,石英砂颗粒中的Si原子所处的化学环境发生明显改变,使其电子密度降低,表明生物胶结物质与石英砂颗粒间形成了新的作用,而这种作用正是微生物水泥胶结的本质,而这种微观作用的大小导致了不同微生物水泥胶结砂体的宏观性能差异。
[Abstract]:Microbial cement based on microorganism induced deposition and mineralization can consolidate loose particles, low energy consumption and less pollution. In the fields of foundation reinforcement and dust treatment, some disadvantages of traditional materials can be solved, such as high energy consumption in production, high chemical toxicity and so on. It is a new kind of cementitious material for sustainable development. At present, the research of biological calcium carbonate cement is the most extensive, but it mainly aims at its preparation and application. Through screening, a phosphate microorganism suitable for cementation has been developed. Biophosphate cementitious materials are deposited on specific substrates and mineralized. At the same time, macroscopical cementing properties, The differences between biocarbonate cement and biophosphate cement were compared in terms of the properties of the cementation interface and the microcosmic interaction between the cementing materials and the particles. The main research results are as follows: using a phosphate mineralized microorganism, the biophosphate deposition products are synthesized by the interaction and mineralization of a specific substrate. The results showed that the product was hydroxyapatite, and the microcosmic morphology was nano-spherical agglomerate. The deposition conditions of biophosphate in solution system were optimized. The basic formula of biophosphate was determined. By comparing and studying different microbial cement cemented sand bodies, the permeability coefficient and porosity of biological calcium carbonate cemented sand body were obviously higher than those of other experimental groups under the condition of similar sand body strength. However, the cement content in sand is lower than that in other experimental groups, indicating that the strength of biocalcium carbonate per unit mass is higher than that of other microbial cement. The results of ultrasonic oscillation debonding experiment showed that the calcium carbonate deposited on the glass was obvious, the particle distribution was uniform, and the interface between the calcium carbonate and the glass was strong. The others are biological guano stone, biological barium phosphate and chemical calcium carbonate, while biocalcium phosphate deposit is the worst. The scratch test results further verify the above rule. The relationship between the interface bonding strength and the amount of cemented material deposition can be seen. The interfacial bonding strength of biocalcium carbonate per unit mass is the highest, which is consistent with the cementation strength of sand body. The interaction between biological cemented substance and loose sand particles is studied by means of X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) analysis. The results show that the chemical environment of Si atoms in quartz sand particles is changed obviously in microbial mineralized deposition, which results in the decrease of electron density, which indicates that there is a new interaction between biocynthesis and quartz sand particles. This kind of action is the essence of microbial cement cementing, and the microcosmic effect leads to the difference of macroscopic properties of different microorganism cement cementing sand bodies.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ172.1

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