内掺微生物水工混凝土的抗渗性能试验研究

有效改善水工混凝土防渗体的抗渗性能是提高其耐久性的关键。本文通过开展内掺科氏芽孢杆菌的水工混凝土抗渗试验，分析内掺不同浓度科氏芽孢杆菌对水工混凝土抗渗性能的影响规律；通过氮吸附试验，分析水工混凝土试样的微观孔隙特征，揭示内掺科氏芽孢杆菌对水工混凝土抗渗性能的影响机制。结果表明：内掺矿化微生物可显著提升水工混凝土的抗渗性能；随着内掺微生物浓度的增大，混凝土28 d水渗透性系数降幅呈先大后小的趋势，当内掺微生物浓度为9.8×10⁷ cells/mL时，混凝土的水渗透性系数降幅最大，28 d混凝土水渗透性系数减小了92%；氮吸附微观分析可知，混凝土内掺微生物可减少中大孔数量、细化孔隙，最可几孔径峰值降幅达47.65%，有效改善了混凝土内部的孔隙结构，降低了孔隙连通性，致使水工混凝土的抗渗性能有效提高。

Experimental study on impermeability of hydraulic concrete with microorganisms

Effective improvement of the impermeability of hydraulic anti-seepage concrete structures is the key to durability enhancing. In this work, we conduct impermeability tests on hydraulic concrete mixed with Bacillus Coriolis, and analyze the influence of the additive concentration on impermeability. Through nitrogen adsorption tests, we examine the micro-pore characteristics of concrete samples, and reveal the influencing mechanism of Bacillus Coriolis on impermeability. The results show the impermeability of concrete can be significantly improved by adding mineralized microorganisms. With the increase in microbial concentration, the water permeability coefficient of the 28 d concrete samples tends to decrease sharply and then slowly; at a microbial concentration of 9.8×107 cells/mL, the decrease of 92% is the largest. Micro-analysis of nitrogen adsorption shows that adding microorganisms into concrete reduces the number of medium- and large-size pores and refines the concrete pore size, and that the peak diameters of the most probable holes are reduced by up to 47.7%. This improves effectively the pore structure in hydraulic concrete and reduces its pore connectivity, thus enhancing its impermeability significantly.