Permeation properties of concrete made with fly ash and silica fume: Influence of ureolytic bacteria
Permeation properties of concrete made with fly ash and silica fume: Influence of ureolytic bacteria
复制标题
DOI：
10.1016/j.conbuildmat.2013.08.023
复制
发表时间：
2013-12-01
影响因子：
7.4
通讯作者：
Siddique, Rafat
中科院分区：
文献类型：
--
作者：
Chahal, Navneet;Siddique, Rafat
通过使用涉及细菌诱导方解石沉淀的新技术可以提高混凝土的耐久性。细菌能够通过在过饱和 CaCO3 溶液中提供异质晶体成核位点来沉淀碳酸钙。研究工作的最初目标涉及从碱性土壤中分离产生脲酶的细菌。通过在水泥/混凝土的碱性环境中维持自身的能力来鉴定细菌。通过 DNA 测序对细菌分离株进行分析，该细菌被鉴定为巴氏孢子八叠球菌，当其在脲酶琼脂和肉汤上生长时，显示出最大的脲酶产量。该研究工作的重要目标还涉及在混凝土中使用尿素分解细菌（巴斯德酵母），使其能够自我修复。混凝土中存在的细菌通过方解石的生产迅速密封了新形成的裂缝。细菌浓度优化为10(3)、10(5)和10(7)细胞/ml。在混凝土混合物中，水泥被粉煤灰和硅粉代替。粉煤灰和硅粉的替代百分比以水泥重量计。粉煤灰的使用比例为0%、10%、20%和30%，硅粉的使用比例为0%、5%和10%。通过实验评估巴氏酵母对粉煤灰和硅粉混凝土抗压强度、吸水率、孔隙率和快速氯离子渗透性的影响，直至龄期为 91 天。试验结果表明，掺入巴氏酵母提高了粉煤灰和硅灰混凝土的抗压强度，降低了孔隙率和渗透率。抗压强度的提高是由于孔内细菌细胞表面的沉积，通过电子显微镜扫描并通过 XRD 证实，显示碳酸钙沉淀。这种沉淀降低了含有飞灰和硅灰的混凝土中氯离子的渗透性。细菌通过改善混凝土的孔隙结构来提高混凝土的渗透性，从而提高混凝土结构的寿命。 (C) 2013 Elsevier Ltd. 保留所有权利。
Durability of concrete can be enhanced by using a novel technique which involves bacterial-induced calcite precipitation. Bacteria are capable of precipitating calcium carbonate by providing heterogeneous crystal nucleation sites in super-saturated CaCO3 solution. The initial objective of the research work involved the isolation of urease producing bacteria from alkaline soil. The bacteria were identified by the ability to sustain itself in alkaline environment of cement/concrete. The bacterial isolate was analyzed through DNA sequencing and the bacteria was identified as Sporosarcina pasteurii, which showed maximum urease production when it was grown on urease agar and broth. The significant objective of the research work further involved the use of ureolytic bacteria (S. pasteurii) in concrete which would make it, self-healing. The bacteria present in the concrete rapidly sealed freshly formed cracks through calcite production. The bacterial concentrations were optimized to 10(3), 10(5) and 10(7) cells/ml. In concrete mix, cement was replaced with fly ash, and silica fume. The percentage replacement of fly ash and silica fume was by weight of cement. The percentage use of fly ash was 0%, 10%, 20% and 30%, and that silica fume were 0%, 5% and 10%. The experiments were carried out to evaluate the effect of S. pasteurii on the compressive strength, water absorption, water porosity and rapid chloride permeability of concrete made with fly ash and silica fume up to the age 91 days. The test results indicated that inclusion of S. pasteurii enhanced the compressive strength, reduced the porosity and permeability of the concrete with fly ash and silica fume. The improvement in compressive strength was due to deposition on the bacteria cell surfaces within the pores which was scanned by electron microscopy and confirmed by XRD which revealed calcium carbonate precipitation. This precipitation reduced the chloride permeability in concrete with fly ash and silica fume. The bacteria improve the permeability of concrete by improving its pore structure and thereby enhancing the life of concrete structures. (C) 2013 Elsevier Ltd. All rights reserved.