好氧混菌矿化能力与增强再生粗骨料性能研究

Mineralization Capacity of Aerobic Mixed Cultures of Bacteria and Performance Enhancement of Recycled Coarse Aggregates

微生物矿化沉积方法利用矿化微生物代谢生成的碳酸钙能够对混凝土裂缝或再生骨料缺陷进行有效地修复,然而目前基于微生物矿化修复材料缺陷研究大多数采用单一类型的微生物,其培养成本高并且矿化鲁棒性不足。筛选了一种适用于增强再生混凝土骨料性能的好氧嗜碱混菌,以提高矿化鲁棒性并显著降低培养成本。首先考察矿化沉积时间、钙离子浓度、乳酸和菌液浓度对该混菌矿化效率的影响,并将其矿化效率与科氏芽孢杆菌进行对比;然后采用该混菌对再生粗骨料进行矿化增强以验证其有效性。试验结果表明,随着矿化时间的延长,混菌矿化沉淀量呈现出先增大后趋于稳定的变化规律;钙离子浓度过高反而会抑制混菌矿化效率,提高菌液浓度能够有效地改善混菌矿化效率;相同环境条件下混菌的矿化效率明显优于科氏芽孢杆菌。经混菌矿化增强的再生粗骨料吸水率和压碎指标降低幅度可分别达到44.6%和30%,验证了筛选混菌的有效性。

Microbially induced carbonate precipitation can effectively heal the concrete cracks or recycled aggregate defects. However, previous studies mostly use pure cultures of bacteria, leading to the problems of high cost and low robustness of pure cultures. Aerobic alkaliphilic mixed cultures of bacteria for enhancing the performance of recycled concrete aggregate were screened to improve the mineralization robustness and reduce the overall cost. The effects of mineralized time, calcium ion concentration, lactic acid concentration, bacterial solution concentration and calcium source on the mineralization efficiencies of the mixed cultures were firstly investigated. Its mineralization efficiency was also compared with that of Bacillus cohnii. Then, the effectiveness of the mixed cultures on the performance enhancement of recycled coarse aggregate was verified. It shows that the precipitation amounts of mixed cultures exhibited first increasing and then stable variation trend with the time extension. Higher calcium ion concentration would inhibit the mineralization efficiency of mixed cultures. Increasing concentration of bacterial solution can effectively improve the mineralization efficiency of mixed cultures. Moreover, the mineralization efficiency of mixed cultures was significantly higher than that of Bacillus cohnii under the same environmental conditions. In addition, the water absorption and crushing index of the enhanced recycled coarse aggregates decreased by 44.6% and 30%, respectively. The effectiveness of screened mixed cultures of bacteria was verified.