三合土表面微生物诱导碳酸钙沉淀耐水性试验研究

Experimental study on water resistance of tabia surface with microbially induced carbonate precipitation

水害是引起土遗址表面侵蚀的最主要因素之一,利用微生物诱导碳酸钙沉淀(MICP)技术在三合土材料表面形成耐水保护层,以达到提高三合土材料耐水性的目的。通过静态接触角试验、毛细吸水试验、Karsten管试验、耐久性试验、耐酸性试验、水蒸气渗透性试验和表面颜色变化试验评估碳酸钙保护层对三合土材料的保护效果,并分析细菌和胶结液浓度对保护效果的影响。试验结果表明,微生物诱导的碳酸钙沉淀通过改变土样表面的微观结构,可大幅度提高其耐水性;较高的细菌和胶结液浓度可以使沉淀层起到较佳的保护作用,但其影响并不是线性的,细菌溶液存在一个适宜浓度,小于该浓度时,细菌浓度的改变对处理试样的耐水性影响较大,当超过该浓度时,细菌浓度的改变对处理试样的耐水性影响并不明显,细菌适宜浓度的发现可以在保证MICP技术工程实际应用效果的同时,提高其经济性;微生物诱导的碳酸钙沉淀保护层不仅耐久性良好,而且对样品本身的透气性和颜色影响较小。MICP技术可作为缓解土遗址表层风化的有效方法。

Water is one of the most important factors causing surface erosion of earthen sites. In this study,microbially induced carbonate precipitation(MICP) technique was used to form a water-resistant layer on the surface of tabia,and the applicability of MICP for tabia surface erosion control was examined by the static contact angle test,capillary water absorption test,Karsten tube test,durability test,acid resistance test,water vapor permeability test and surface color change test in the laboratory. The effect of the concentration of bacteria and cementation solution on the surface erosion control was analyzed. The test results show that MICP can significantly improve the water resistance of soil samples by changing the microstructure of the surface. A higher concentration of bacteria and cementation solution can make the sediment layer play a better protection in a non-linear form. There is a suitable concentration value of the bacterial solution. When the bacterial concentration is less than the value,the change of the concentration has a great influence on the water resistance of the treated samples. However,the change of the bacterial concentration greater than the value has no obvious effect. The discovery of suitable concentration value can improve the economics of MICP technology on the premise of successful application of MICP in practice. The MICP protection layer not only has good durability,but also has little negative impact on the air permeability and color of the samples. MICP can be used as an effective method to relieve surface erosion of earthen sites.