微生物矿化沉积改善再生骨料性能的机理研究

Reuse of recycled concrete aggregates (RCA) in new concrete structures is of significance to the sustainable development of resource and environment. However, the quality and broad application of RCA is adversely affected by their high water absorption, porosity, crushing value and dispersion. Researchers have investigated various modification methods to improve the quality of RCA. Unfortunately, those methods are burdened with a number of disadvantages, such as high energy consuming, high cost and secondary contamination. In this project, a method of biodeposition of calcium carbonate through the participation of bacteria is used as an alternative method to modify the properties of RCA. Microbial carbonate precipitation (MCP) is a natural method and entire new approach, in principle, makes less severe to the environment and low energy consumption. The suitable bacteria and surviving environment are selected through various trials. The effect of homogeneous quality of RCA from different sources by MCP modification is achieved by aggregate tests. The theoretical relationship between the MCP and RCA is finally established through performance investigation on concrete with natural aggregate replaced by modified RCA combined with microstructural analyzation. The MCP modification seems to be a promising technique in the improvement of the quality of RCA. It is meaningful for improving the quality of RCP with high efficiency, low energy consumption and less environmental damage, as well as broadening the application prospect of RCA.

将建筑废弃物制成再生骨料代替天然骨料，对于资源、环境和可持续发展具有重要意义。但再生骨料具备吸水率高、孔隙率大、压碎指标值高、品质离散性大等特点，影响再生混凝土性能，限制了再生骨料的应用。国内外学者对再生骨料提出了若干改性方法，但是这些方法存在能耗大、成本高、容易造成二次污染等问题。本项目利用某些微生物自身新陈代谢产生碳酸钙沉积来改善再生骨料性能，低能耗，无污染，是一个全新的研究方向。通过在不同条件下试验分析，优选出最适宜的菌种和环境因素；通过对不同来源再生骨料试验研究，得出微生物矿化沉积改性对再生骨料品质均一化的效果；使用改性的再生骨料制备再生混凝土，研究其对再生混凝土性能的影响规律；结合微观测试分析，最终建立微生物矿化沉积与再生骨料之间的理论联系。实现高效率、低能耗、无污染地改善再生骨料性能，拓展再生混凝土应用，具备重要的研究意义与广阔的应用前景。

将建筑废弃物制成再生骨料代替天然骨料，对于资源、环境和可持续发展具有重要意义。本项目利用某些微生物自身新陈代谢产生碳酸钙沉积来改善再生骨料性能，低能耗，无污染，是一个全新的研究方向。通过为期4年的研究，本项目研究了不同菌种的微生物矿化活性的影响因素、比较了不同钙源下和不同骨料的矿化效果，采用了添加释氧剂和喷淋的方式增强微生物矿化沉积的效果。利用微生物矿化沉积处理的再生骨料，分别制备了砂浆和混凝土，通过对其力学性能、孔隙结构以及微观产物的研究和分析，最终建立微生物矿化沉积与再生骨料性能之间的理论联系，为高效、无污染地改善再生骨料性能提供了一条新的技术途径。