MICP改良灰浆物理性能的实验研究

Experimental Study on the Physical Properties of MICP Improved Mortar

灰浆是近代文物建筑本体安全的重要组成材料,由于灰浆内部盐分析出,泛碱破坏频发,且受外界环境反复作用,灰浆物理性能逐渐衰减,使近代文物建筑破损严重.如何有效抑制泛碱破坏,提高灰浆物理性能,成为近代文物建筑修复的难点问题之一.基于微生物诱导方解石沉积(Microbially Induced Carbonate Precipitation,MICP)原理,以近代灰浆组成为依据配置实验灰浆,通过分析微生物脲酶活性影响因素,开展MICP改良灰浆物理性能实验,测试矿化后灰浆的电导率、盐度、质量和无侧限抗压强度,分析矿化作用对灰浆物理特性的影响规律,并对比分析矿化灰浆的矿物成分和微观结构特征.实验结果表明,灰浆经过MICP 3次浸泡处理后,电导率及盐度值分别降低了62.5%、67.4%,减少了盐分析出的可能性,减弱了泛碱破坏;MICP矿化处理可以有效改良灰浆的物理性能,3次矿化为最佳矿化周期,灰浆试块的质量和无侧限抗压强度同比增长1.09%、9.92%;SEM和EDS从矿物成分和微观结构特征方面证实了灰浆中阳离子得到固定,生成的碳酸钙沉淀填充了结构孔隙,改善了灰浆内部结构.研究成果为近代文物建筑灰浆修复提供了新方法.

Mortar is an important component for the safety of modern cultural relics.Due to the analysis of the internal salt of the mortar,efflorescence damage occurs frequently,and the physical properties of the mortar are gradually attenuated by the repeated effects of the external environment,causing serious damage to the modern cultural relics.How to effectively suppress efflorescence damage and improve the physical properties of mortar has become one of the difficult problems in the restoration of modern cultural relics.Based on the Microbially Induced Carbonate Precipitation(MICP),the test mortar is configured based on the composition of modern mortar,and the physical properties of the MCP modified mortar are tested by analyzing the influencing factors of microbial urease activity to test the electrical conductivity,salinity,quality and unconfined compressive strength of the mineralized mortar.The influence of mineralization on the physical properties of mortar is analyzed,and the mineral composition and microstructure characteristics of mineralized mortar are compared and analyzed.The test results showed that the conductivity and salinity of the mortar were reduced by 62.5%and 67.4%after three times of MICP immersion treatment,which reduced the possibility of salt analysis and weakened efflorescence damage.The MICP mineralization treatment can effectively improve the physical properties of the mortar.The 3 times of mineralization is the best mineralization cycle.The quality and unconfined compressive strength of the mortar test block have increased by 1.09%and 9.92%year-on-year.SEM and EDS confirmed the fixation of cations in the mortar from the aspects of mineral composition and microstructure characteristics,and the formed calcium carbonate precipitate filled the structural pores and improved the internal structure of the mortar.The research results provide a new method for mortar restoration of modern cultural relics.