Biologically-Inspired Silicification of Fine-Grained Soils

细粒土壤的生物启发硅化

• 批准号: 1301124
• 负责人: Joseph Dove
• 金额: $ 38.77万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-03-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1301124&HistoricalAwards=false
• 关键词: Biologically; Inspired; Silicification; Fine; Grained

Many organisms mineralize tissues to produce structures that serve diverse functions such as skeletal support and protective composite layers. These structures are formed through biomineralization processes that have low metabolic cost to the organism. Of particular interest is the process of biosilicification -- the ability of organisms to direct the nucleation and growth of mechanically efficient silica skeletal materials. Advances in biosilicification research present an opportunity for cross-fertilization between the seemingly disparate disciplines of biomineralization and geotechnical engineering to advance ground improvement technology. The goals of this project are to: 1) Uncover new pathways for silica polymerization in fine-grained soil, 2) Use insights from biosilicification research to develop new processes for forming amorphous silica cements at natural pH levels using environmentally benign chemical materials, and 3) Reduce the life cycle impacts associated with ground improvement. To achieve the project goals, laboratory experiments will be conducted to model the geotechnical construction practices of subgrade stabilization using wet and dry soil mixing. Lime and cement stabilized samples will be used as control treatments. Soil materials that consist of pure clay minerals, mixtures of the clay minerals, mine tailings, and natural soils will be silicified with a polycation and sodium silicate. Adsorption and silicification-caused changes in soil geochemical properties will be assessed by x-ray diffraction, zeta potential, surface area, cation exchange capacity and pH. Changes in geotechnical index properties due to treatment will be determined and used to optimize the experiments. Strength of silicified soil will be measured by unconfined compression, consolidated undrained triaxial compression tests. Consolidation and creep tests will be used to evaluate strength and compressibility changes. The potential for the silicification process to reduce the volume changes associated with expansive soil will be determined. Pilot scale field tests will guide development of field implementation methods and to improve treatment effectiveness. Findings from this project will benefit society by reducing the life cycle environmental impacts of geotechnical construction, and training of the next generation of geotechnical engineers. Current ground treatment processes can possess relatively high embodied energy, and they rely on resources that cannot be renewed on human time scales. There can also be impacts to soil and groundwater and significant releases of CO2 to the atmosphere. The silicification process offers the potential for using reduced amounts of environmentally friendly input materials to achieve engineering performance that is comparable to or better than current technologies. By reducing the environmental impact, this new process has the potential to lower the cost of infrastructure projects. The findings also have the potential to benefit the resource recovery industries in managing fine-grained tailings. Graduate students will receive interdisciplinary training and will have the unique opportunity to develop expertise in the rapidly growing areas of applied biogeochemistry and biologically inspired materials.

许多生物矿化组织，以产生结构，服务于不同的功能，如骨骼支持和保护复合层。 这些结构是通过生物矿化过程形成的，对生物体具有低代谢成本。 特别令人感兴趣的是生物硅化的过程-生物体的能力，以指导成核和生长的机械有效的二氧化硅骨架材料。 生物硅化研究的进展为生物矿化和岩土工程这两个看似不同的学科之间的交叉施肥提供了一个机会，以推进地基加固技术。 该项目的目标是：1）揭示细粒土壤中二氧化硅聚合的新途径，2）利用生物硅化研究的见解，开发使用环境友好的化学材料在自然pH值水平下形成无定形二氧化硅水泥的新工艺，以及3）减少与地面改良相关的生命周期影响。 为了实现项目目标，将进行实验室试验，模拟使用干湿土混合进行路基稳定的岩土工程施工实践。 石灰和水泥稳定样品将用作对照处理。 由纯粘土矿物、粘土矿物混合物、尾矿和天然土壤组成的土壤材料将用聚阳离子和硅酸钠进行硅化。 吸附和硅化引起的土壤地球化学性质的变化将通过X射线衍射，zeta电位，表面积，阳离子交换容量和pH值进行评估。由于处理的岩土工程指标特性的变化将被确定，并用于优化实验。 硅化土的强度将通过无侧限压缩、固结不排水三轴压缩试验来测量。 固结和蠕变试验将用于评估强度和压缩性变化。 将确定硅化过程减少与膨胀土相关的体积变化的潜力。 试点规模的实地测试将指导制定实地实施方法，并提高治疗效果。 该项目的研究结果将通过减少岩土工程建设的生命周期环境影响和培训下一代岩土工程师来造福社会。 目前的地基处理过程可以拥有相对较高的能量，并且它们依赖于在人类时间尺度上不能更新的资源。 还可能对土壤和地下水产生影响，并向大气中排放大量二氧化碳。 硅化工艺提供了使用减少量的环保投入材料以实现与当前技术相当或更好的工程性能的可能性。 通过减少对环境的影响，这种新工艺有可能降低基础设施项目的成本。 这些发现也有可能使资源回收行业在管理细粒尾矿方面受益。研究生将接受跨学科的培训，并将有独特的机会，在应用地球化学和生物启发材料的快速增长领域发展专业知识。