Microbial concrete has high potential for superior strength and durability, provided the optimal combination of bacterial cell concentration and water/cement (w/c) ratio is used. Despite there being a considerable volume of the literature on microbial concrete, no work has so far dealt with the prediction of compressive strength and water absorption, the most essential properties of concrete, at different levels of bacterial concentrations and w/c ratios. In addition, there has been no investigation on the optimization of bacterial concentration and w/c ratio with respect to these properties, which is very important from the microbial concrete mix design point of view. The present work addresses these issues and develops models to predict the compressive strength and water absorption of mortar mix within a range of commonly used w/c ratios, namely 0.40, 0.45 and 0.50, and cell concentrations of Bacillus subtilis, namely 10³, 10⁵ and 10⁷ cells/ml of water, to circumvent detailed case-specific experimental investigation. This is achieved by applying response surface methodology using the Design-Expert software to experimental data obtained for nine combinations of w/c ratios and bacterial cell concentrations. Analysis of variance (ANOVA) is carried out to acquire simplified updated models. Optimal values of cell concentration and w/c ratio that maximize mortar compressive strength and minimize its water absorption are obtained, which lies between 10^5.719 and 10^5.8 cells/ml at w/c ratio of 0.40. Further, the optimal cell concentration for a preset w/c ratio is provided, which is highly pertinent from the practical application point of view. Finally, a microstructure analysis is carried out to offer insight into the obtained optimal cell concentrations.

微生物混凝土具有优异的强度和耐久性，如果使用细菌细胞浓度和水/水泥（w / c）比的最佳组合，则具有很高的潜力。尽管学生相当体积上的微生物的具体文献中的，没有工作迄今处理的抗压强度和吸水率，混凝土的最本质的属性的预测，在不同级别的细菌浓度和瓦特/ Ç比率。此外，还没有关于优化细菌浓度和w / c的研究。相对于这些性能的比率，这从微生物混凝土配合比设计的角度来看非常重要。本工作解决了这些问题，并开发模型来预测的范围内混合砂浆的抗压强度和吸水性的常用瓦特/ Ç比率，即0.40，0.45和0.50，并且细胞浓度枯草芽孢杆菌，即10 ³，10 ⁵和10 ^7个细胞/毫升的水，以规避针对具体案例的详细实验研究。这是通过使用Design-Expert软件将响应面方法应用于针对w / c的九种组合而获得的实验数据来实现的比和细菌细胞浓度。进行方差分析（ANOVA）以获取简化的更新模型。获得了使灰浆抗压强度最大化和其吸水率最小的泡孔浓度和w / c比的最佳值，该值介于10 ⁵之间^。719和10 ^{5 。}w / c比为0.40时为^8个细胞/ ml 。此外，预设w / c的最佳细胞浓度提供了比率，这从实际应用的角度来看是高度相关的。最后，进行微结构分析，以深入了解获得的最佳细胞浓度。