Abstract

Seawater based bio-cementation through microbially-induced carbonate precipitation was proposed for the calcareous sand improvement in marine environment. The method used seawater instead of traditional fresh water to culture urease producing-bacteria (UPB) and prepare cementation solution (CS) for the bio-cement. A series of comparative bio-treatment tests using seawater based bio-cementation and traditional bio-cementation methods on three types of soil were conducted. Experimental results indicate that seawater based bio-cementation method has the ability to improve soil physico-mechanical properties, and performed better than traditional bio-cementation method. The dominant reason can be explained as that the mixture of the productions of calcite, monohydrocalcite and calcite magnesium produced during seawater based bio-cementation process have better cementation ability than the mixture of the productions of calcite and vaterite produced during bio-cementation process. UCS of coarse Ottawa sand blocks are smaller than that of medium Ottawa sand blocks is because the specific surface area of fine sand is higher and larger number of effective bondings can be formed. UCS of calcareous sand blocks are smaller than those of coarse Ottawa sand blocks can be attributed to the fact that calcareous sand has higher porosity and rougher surface, resulting in more carbonate crystals being precipitated on un-connected locations.

摘要

提出了通过微生物诱导碳酸盐沉淀的海水基生物胶结用于改善海洋环境中的钙质砂。该方法利用海水代替传统淡水培养产脲酶细菌（UPB）并制备生物水泥的固结液（CS）。使用海水生物胶结和传统生物胶结方法对三种类型的土壤进行了一系列生物处理对比试验。实验结果表明，海水基生物胶结法具有改善土壤物理力学性质的能力，且效果优于传统生物胶结法。主要原因可以解释为方解石产品的混合物，海水基生物胶结过程中产生的一水方解石和方解石镁比生物胶结过程中产生的方解石和球霰石产物的混合物具有更好的胶结能力。粗渥太华砂块的UCS比中渥太华砂块的UCS小，是因为细砂的比表面积更大，可以形成更多的有效粘结。钙质砂块的UCS比粗渥太华砂块小，可能是因为钙质砂具有较高的孔隙率和较粗糙的表面，导致更多的碳酸盐晶体在不相连的位置沉淀。粗渥太华砂块的UCS比中渥太华砂块的UCS小，是因为细砂的比表面积更大，可以形成更多的有效粘结。钙质砂块的UCS比粗渥太华砂块小，可能是因为钙质砂具有较高的孔隙率和较粗糙的表面，导致更多的碳酸盐晶体在不相连的位置沉淀。粗渥太华砂块的UCS比中渥太华砂块的UCS小，是因为细砂的比表面积更大，可以形成更多的有效粘结。钙质砂块的UCS比粗渥太华砂块小，可能是因为钙质砂具有较高的孔隙率和较粗糙的表面，导致更多的碳酸盐晶体在不相连的位置沉淀。