Fukue Masaharu, Lechowicz Zbigniew, Mulligan Catherine N, Takeuchi Seiichi, Fujimori Yuichi, Emori Kentaro
Japanese Geotechnical Association for Housing Disaster Prevention, 1622, Oshikiri, Shimizu-ku, Shizuoka 424-0008, Japan.
Department of Geotechnical Engineering, Institute of Civil Engineering, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland.
Materials (Basel). 2025 Feb 12;18(4):809. doi: 10.3390/ma18040809.
Research on MICP technology for ground improvement began in the early 2000s, and since then, it has been considered as innovative research. The field of applications is showing signs of expanding from sandy soil stabilization to remediation. However, the research has not always progressed, because it is extremely difficult to evaluate the ability (viability rate) related to microorganisms and how to handle them quantitatively. In fact, this problem hinders the consensus of research results in terms of quantitative evaluation of microorganisms and the cross-comparison (evaluation) and use of MICP technology research. The crucial disadvantage of using bacteria is that their properties are not constant due to changes over time and in the surrounding environment. Therefore, for engineering purposes, we used the carbonate formation rate (CPR), instead of urease activity, as a function of the microbial mass (OD) with viable bacteria. Thus, the standard OD-CPR relationship was defined experimentally, and the estimation method of viability was established. The required amount of microorganisms for testing was given by OD*, and the relationship "OD = Rcv OD*" was defined to convert from OD* to OD. Rcv was defined as the viable bacterial rate. It was found that the Ca/OD ratio controls the inhibition behavior in MICP. At a Ca/OD ratio of >8.46 M, then inhibition occurs, while at Ca/OD = 8.46 M, CPR = 8.46 OD and the CPR is proportional to the viable OD, Rcv, and OD*. We show that it is possible to perform an experiment using OD* with aged bacteria, obtain Rcv from the standard OD-CPR and OD*-CPR relationships, convert OD* to OD and to perform a unified evaluation without actually determining the viability rate.
微生物诱导碳酸钙沉淀（MICP）技术用于地基处理的研究始于21世纪初，自那时起，它就被视为创新性研究。其应用领域正显示出从砂土稳定扩展到修复的迹象。然而，该研究并非一直顺利进行，因为评估与微生物相关的能力（存活率）以及如何对其进行定量处理极其困难。事实上，这个问题阻碍了在微生物定量评估以及MICP技术研究的交叉比较（评估）和应用方面达成研究结果共识。使用细菌的关键缺点在于，由于随时间和周围环境的变化，它们的特性并不稳定。因此，出于工程目的，我们使用碳酸盐生成速率（CPR）而非脲酶活性，将其作为具有活性细菌的微生物量（OD）的函数。由此，通过实验定义了标准的OD-CPR关系，并建立了存活率的估算方法。测试所需的微生物量由OD给出，定义了“OD = Rcv OD”的关系以从OD转换为OD。Rcv被定义为活性细菌率。研究发现，Ca/OD比值控制着MICP中的抑制行为。当Ca/OD比值>8.46 M时，会发生抑制，而当Ca/OD = 8.46 M时，CPR = 8.46 OD，且CPR与活性OD、Rcv和OD成正比。我们表明，使用老化细菌的OD进行实验、从标准OD-CPR和OD-CPR关系中获取Rcv、将OD*转换为OD并进行统一评估而无需实际测定存活率是可行的。
