微生物诱导碳酸钙沉积修复混凝土裂缝的试验研究
发布时间：2019-04-11 20:02
【摘要】：混凝土作为当前应用最为广泛的建筑材料,其开裂后造成的渗漏问题一直困扰着工程界。渗漏问题会影响到混凝土的抗渗性和耐久性,导致混凝土构件的承载能力降低。目前,混凝土渗漏的修复方法有很多,但大都存在着粘结性及耐久性差、污染环境等缺点。近年来随着科技的发展,微生物诱导碳酸钙沉积修复技术以其修复效果好、绿色环保等优点逐步成为科研人员的研究重点。该技术利用微生物新陈代谢活动中产生的尿素酶将尿素分解出碳酸根离子,然后与环境中的钙离子结合生成碳酸钙晶体沉积于开裂部位,从而实现对混凝土裂缝的修复。本试验利用巴氏芽孢杆菌诱导碳酸钙沉积进行混凝土裂缝的封堵,通过设定不同的影响因素及抗渗试验来检验其修复效果。试验的主要内容和结论有：1、研究了菌液中提前加入尿素对碳酸钙早期产率的影响。结果表明：在菌液中提前加入尿素可以促使碳酸钙的生成速率爆发区间提前,有效提高碳酸钙的早期产率。2、试验发现微生物的活性是影响微生物封堵速度的重要因素。在一定范围内,微生物的活性越强,诱导产生的碳酸钙越多,封堵混凝土裂缝的速度越快。3、研究了不同因素(缝宽、缝深、介质、钙源)对微生物灌浆封堵混凝土裂缝的影响。结果表明：微生物灌浆封堵混凝土裂缝速度的影响因素从大到小依次是缝宽、缝深和介质、钙源；在其它条件不变的情况下,缝宽越小,缝深越大,或在较宽的裂缝中填充介质后灌菌等方法可加快裂缝封堵速度。钙源可以选择对钢筋无腐蚀作用的醋酸钙或硝酸钙。4、通过冲压试验研究了微生物封堵完成后混凝土裂缝的抗渗效果。结果表明：采用微生物修复技术封堵的混凝土裂缝具有较好的抗渗性能。裂缝宽度、裂缝深度等都是影响封堵后混凝土裂缝抗渗效果的重要因素。在其它条件不变的情况下,缝宽越小,缝深越大,或在较宽的裂缝中采用先填充介质后灌菌等方法,可有效提高封堵后混凝土裂缝的抗渗性能。5、由微生物灌浆封堵混凝土裂缝的机理可知：裂缝宽度越小越有利于碳酸钙晶体的捕获、架桥和沉积。裂缝深度越大,意味着碳酸钙晶体流经裂缝的距离和时间越长,增加了其在混凝土裂缝内架桥和沉积的几率。在宽的裂缝中填充介质后,可将裂缝分割为多个小裂缝,同时摩擦力也增加。因此,缝宽越小,缝深越大,或在较宽的裂缝中采用先填充介质不仅加快了裂缝封堵速度,而且提高了其抗渗性能。
[Abstract]:Concrete, as the most widely used building material, has been perplexing the engineering field because of the leakage caused by its cracking. Leakage will affect the impermeability and durability of concrete and reduce the bearing capacity of concrete members. At present, there are many repair methods for concrete leakage, but most of them have some disadvantages such as poor adhesion and durability, environmental pollution and so on. In recent years, with the development of science and technology, microbial-induced calcium carbonate deposition remediation technology has gradually become the research focus of researchers because of its advantages such as good remediation effect, green environmental protection and so on. The technology uses urease from microbial metabolism to decompose urea into carbonate ions, and then combine with calcium ions in the environment to form calcium carbonate crystals deposited on the cracking site, so as to repair concrete cracks. In this experiment, calcium carbonate deposition induced by Bacillus pasteurium was used to seal the cracks of concrete, and the repair effect was tested by setting different influencing factors and impermeability test. The main contents and conclusions of the experiment are as follows: 1. The effect of urea on the early yield of calcium carbonate was studied. The results showed that adding urea in the bacterial solution ahead of time could advance the interval of calcium carbonate formation and effectively improve the early yield of calcium carbonate. 2. It was found that the activity of microorganism was an important factor affecting the rate of microbial plugging. Within a certain range, the stronger the activity of microorganisms, the more calcium carbonate induced, and the faster the rate of sealing concrete cracks. 3. Different factors (crack width, seam depth, medium, etc.) Effect of calcium source on microbe grouting to seal concrete cracks. The results show that the influencing factors of microbe grouting sealing concrete crack velocity are crack width, seam depth, medium and calcium source in order from large to small. Under the same other conditions, the smaller the width of the crack, the greater the depth of the seam, or the method of filling the medium with the medium in the wider crack can speed up the sealing speed of the crack. Calcium source can be selected as calcium acetate or calcium nitrate which has no corrosion effect on steel bars. The impermeability of concrete cracks after microbe plugging is studied by stamping test. The results show that the concrete crack sealed by microbial repair technology has better impermeability. Crack width, crack depth and so on are the important factors that affect the anti-seepage effect of concrete cracks after sealing. Under the same other conditions, the smaller the width of the joint, the greater the depth of the joint, or if the medium is filled first and then the bacteria is filled in the wider crack, the impermeability of the concrete crack after sealing can be improved effectively. 5, According to the mechanism of plugging concrete cracks by microbe grouting, the smaller the crack width is, the more favorable it is to capture, bridge and deposit calcium carbonate crystal. The greater the crack depth, the longer the distance and time of calcium carbonate crystal flowing through the crack, which increases the probability of bridging and depositing in the concrete crack. When the medium is filled in a wide crack, the crack can be divided into several small cracks, and the friction force can also be increased. Therefore, the smaller the joint width, the greater the seam depth, or the use of pre-filled medium in the wider cracks not only accelerates the fracture sealing speed, but also improves its impermeability.
【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528
本文编号：2456707
[Abstract]:Concrete, as the most widely used building material, has been perplexing the engineering field because of the leakage caused by its cracking. Leakage will affect the impermeability and durability of concrete and reduce the bearing capacity of concrete members. At present, there are many repair methods for concrete leakage, but most of them have some disadvantages such as poor adhesion and durability, environmental pollution and so on. In recent years, with the development of science and technology, microbial-induced calcium carbonate deposition remediation technology has gradually become the research focus of researchers because of its advantages such as good remediation effect, green environmental protection and so on. The technology uses urease from microbial metabolism to decompose urea into carbonate ions, and then combine with calcium ions in the environment to form calcium carbonate crystals deposited on the cracking site, so as to repair concrete cracks. In this experiment, calcium carbonate deposition induced by Bacillus pasteurium was used to seal the cracks of concrete, and the repair effect was tested by setting different influencing factors and impermeability test. The main contents and conclusions of the experiment are as follows: 1. The effect of urea on the early yield of calcium carbonate was studied. The results showed that adding urea in the bacterial solution ahead of time could advance the interval of calcium carbonate formation and effectively improve the early yield of calcium carbonate. 2. It was found that the activity of microorganism was an important factor affecting the rate of microbial plugging. Within a certain range, the stronger the activity of microorganisms, the more calcium carbonate induced, and the faster the rate of sealing concrete cracks. 3. Different factors (crack width, seam depth, medium, etc.) Effect of calcium source on microbe grouting to seal concrete cracks. The results show that the influencing factors of microbe grouting sealing concrete crack velocity are crack width, seam depth, medium and calcium source in order from large to small. Under the same other conditions, the smaller the width of the crack, the greater the depth of the seam, or the method of filling the medium with the medium in the wider crack can speed up the sealing speed of the crack. Calcium source can be selected as calcium acetate or calcium nitrate which has no corrosion effect on steel bars. The impermeability of concrete cracks after microbe plugging is studied by stamping test. The results show that the concrete crack sealed by microbial repair technology has better impermeability. Crack width, crack depth and so on are the important factors that affect the anti-seepage effect of concrete cracks after sealing. Under the same other conditions, the smaller the width of the joint, the greater the depth of the joint, or if the medium is filled first and then the bacteria is filled in the wider crack, the impermeability of the concrete crack after sealing can be improved effectively. 5, According to the mechanism of plugging concrete cracks by microbe grouting, the smaller the crack width is, the more favorable it is to capture, bridge and deposit calcium carbonate crystal. The greater the crack depth, the longer the distance and time of calcium carbonate crystal flowing through the crack, which increases the probability of bridging and depositing in the concrete crack. When the medium is filled in a wide crack, the crack can be divided into several small cracks, and the friction force can also be increased. Therefore, the smaller the joint width, the greater the seam depth, or the use of pre-filled medium in the wider cracks not only accelerates the fracture sealing speed, but also improves its impermeability.
【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528
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