一种生物水泥的研制

Development of a biological cement

膨润土改性水泥具有良好的抗渗性能,但膨润土的掺入会导致水泥的力学性能下降。针对这一问题,文中研究了微生物诱导碳酸钙沉淀对膨润土改性水泥力学性能的改良。通过室内实验,在胶结液浓度一定时,研究了不同菌浓度对水泥抗压强度的影响。结果表明:当菌浓度(用OD_(600)表示)为2.0时,20%膨润土改性水泥的抗压强度在28 d后增加了74%;水泥中掺入的膨润土占比分别为0,10%,20%,30%,40%时,水泥的强度显著降低,但是加入菌悬液和胶结液养护28 d后,微生物诱导碳酸钙沉淀使膨润土改性水泥的抗压强度分别提高了12%,6%,74%,54%,26%。通过扫描电镜-能谱进行了测试,分析了微生物诱导碳酸钙沉淀对膨润土改性水泥的作用机理,结果表明,碳酸钙的产生和水泥水化膜的破裂是改性膨润土水泥强度提高的主要原因。现场应用显示,生物水泥具有良好的应用价值。由此可见,微生物诱导碳酸钙沉淀是一种绿色环保,可提高膨润土改性水泥强度的有效方法。

Bentonite modified cement has good impermeability. However, the addition of bentonite will lead to the decline of the mechanical properties of cement. In view of this problem, this paper studies the improvement of mechanical properties of bentonite modified cement by microbial induced calcium carbonate precipitation. Based on the laboratory experiment, the influence of different bacteria concentration on the compressive strength of cement was studied when the concentration of cementing solution was constant. The results show that when the bacterial concentration is OD_(600)=2.0, the compressive strength of bentonite modified cement(20% bentonite) increases by 74% after 28 days. When the proportion of bentonite in cement is 0, 10%, 20%, 30% and 40%, the strength of cement decreases significantly. However, the calcium carbonate precipitation induced by microorganism increases the compressive strength of bentonite modified cement by 12%, 6%, 74%, 54%, 26% respectively after 28 days of curing by adding bacteria suspension and cementing solution. The mechanism of calcium carbonate precipitation induced by microorganism on bentonite modified cement was analyzed by SEM-EDS test. The results show that the formation of calcium carbonate and the rupture of cement hydration membrane are the main reasons for the strength improvement of bentonite modified cement. Field application shows that bio-cement has good application value. It can be seen that microbial induced calcium carbonate precipitation is a green and effective method to improve the strength of bentonite modified cement.