载体保护下诱导碳酸钙对水泥砂浆微裂隙的修复作用

Repair mechanism of induced calcium carbonate on microcracks of cement mortar under carrier protection

摘要:

微生物诱导碳酸钙沉淀可有效填补和修复水泥浆凝结过程中难以避免的水化裂隙，提高水泥石力学强度和抗渗性能，从而可减少诱发的水泥微裂缝质量问题。文章以矿化性能良好的枯草芽孢杆菌为研究对象，通过菌种的活化与扩大培养、向水泥浆中不同方式的添加，测试和评价了不同工艺配方与养护条件下的水泥石力学和抗渗性能。结果表明：环境温度、pH值、钙源浓度分别是影响杆菌矿化能力的主要因素，水泥浆的碱性环境（pH值11~13）对杆菌的活性有明显的抑制作用，最大降低矿化能力达15.1%。多孔、吸附性好的页岩陶砂载体可有效降低碱性环境对杆菌活性的影响，相比于直接添加，载体附菌的添加方式可使水泥石抗压、抗折强度和抗渗压力分别提升11.5%、14.8%和33.3%。当菌液吸附率从0%增加到35%时，微生物水泥石的抗压、抗折强度和抗渗压力分别增加10.8%、47.0%以及25.0%。由此可知，研究的微生物微裂隙修复方法可有效提升水泥环力学和抗渗性能，结论可为固井水泥石质量提升和微生物水泥浆应用推广提供良好的指导和借鉴作用。

Abstract:

Microbial-induced calcium carbonate precipitation can effectively fill and repair the inevitable hydration cracks during the cement slurry consolidation process， enhancing the mechanical strength and impermeability of cement stone， thereby reducing many induced well cementing quality issues. This paper focuses on Bacillus subtilis with good mineralization properties， investigating the mechanics and impermeability performance of cement stone under different process formulations and curing conditions， after activation and expansion cultivation of bacterial strains and their addition to cement slurries in various ways. The results indicate that environmental temperature， pH， and calcium source concentration are the main factors affecting the mineralization ability of the bacteria. The alkaline environment of the cement slurry （pH：11~13） has a significant inhibitory effect on bacterial activity， with a maximum reduction in mineralization ability of 15.1%. Porous and adsorbent shale ceramic sand carriers can effectively mitigate the influence of alkaline environment on bacterial activity. Compared to direct addition， the addition of carrier+bacteria can respectively increase the compressive strength， flexural strength， and impermeability pressure of cement stone by 11.5%，14.8%，and 33.3%. When the adsorption rate of the bacteria solution increases from 0% to 35%， the compressive strength， flexural strength， and impermeability pressure of microbial cement stone increase by 10.8%， 47.0%， and 25.0% respectively. Therefore， the microbial cement slurry studied can effectively improve the mechanical and impermeability properties of cement stone， providing valuable guidance and reference for enhancing well cementing quality and promoting the application of microbial cement slurries.