Concentration of cementation solution (CCS) is one of the key factors influencing the cementation effect on soil improvement through the microbially induced carbonate precipitation (MICP) process. To precipitate more calcium carbonate per treatment, a higher CCS is needed. However, the MICP process may be retarded or even terminated with an increase in CCS. This retarding effect can be a major limitation for the MICP-based soil treatment and thus needs to be understood properly. This paper presents a systematic study on the conditions causing retarding and its effect on biocementation. The test results of this study have identified that there is retarding effect of CCS on the MICP process, showing that the calcium conversion efficiency, which represents the amount of calcium that has been converted into calcium carbonate in each treatment, reduces with the increase in CCS, and the concentration of calcium is the control factor. The retarding effect will dominate increasingly when CCS is higher than 1.0 M and the amount of calcium carbonate precipitation will reduce for the given amount and type of bacteria used in this study and become zero with CCS of 2.5 M. For the same calcium carbonate content, the unconfined compressive strength is greater for sand treated using a lower CCS as the contribution to the bonding strength by the calcium carbonate generated under a lower CCS is greater than that under a higher CCS.

胶结溶液（CCS）的浓度是通过微生物诱导的碳酸盐沉淀（MICP）过程影响胶结作用对土壤改良的关键因素之一。为了使每次处理沉淀更多的碳酸钙，需要更高的CCS。但是，随着CCS的增加，MICP过程可能会延迟甚至终止。这种阻滞作用可能是基于MICP的土壤处理的主要局限性，因此需要正确理解。本文对引起阻滞的条件及其对生物胶凝作用的影响进行了系统的研究。这项研究的测试结果已经确定了CCS有延缓作用在MICP过程中的结果表明，钙转化效率随CCS的增加而降低，代表每次处理中已转化为碳酸钙的钙量，而钙的浓度是控制因素。当CCS高于1.0 M时，阻滞作用将越来越占主导地位，并且对于本研究中使用的给定数量和类型的细菌，碳酸钙沉淀的量将减少，而当CCS为2.5 M时，碳酸钙的沉淀量将为零。对于相同的碳酸钙含量，无侧限抗压强度是更大用于使用下处理过的砂子CCS作为被低级下产生的碳酸钙的粘结强度的贡献CCS大于CCS较高的情况。