微生物自修复水泥基材料的护筋性及作用机理

论文总字数：49303字

摘 要

混凝土作为最常用的土木工程材料，被大量运用在各类实际工程当中。但混凝土开裂之后，裂缝为侵蚀物质的传输提供了便捷通道，加速了内部钢筋的锈蚀过程。微生物自修复水泥基材料能够实现裂缝的自修复，且具有成本低，操作简单，纯天然无污染的特点，因此成为最近的研究热点。而目前对微生物自修复水泥基材料的研究主要集中在矿化机理，裂缝修复效果和强度恢复等方面，对护筋性研究较少。所以本课题通过将微生物自修复水泥基材料与普通水泥基材料进行对比，比较二者在氯离子侵蚀环境、碳化环境和杂散电流环境中的护筋性差异，还将试件开裂前、开裂修复前和修复后的护筋性进行对比，研究护筋性的变化过程。

研究发现，在试件开裂前，微生物自修复水泥基材料的护筋性优势并不明显，自修复剂的加入使得基体抗氯离子侵蚀、抗碳化以及抗杂散电流等性能方面略有降低，试件内部钢筋的电化学测试结果以及实际的锈蚀情况均比对照组的也要略严重一些。主要原因在于微生物自修复剂具有一定的引气效果，使得基体的大孔结构增多，降低结构的密实程度。但通过对钢筋锈蚀差异的分析发现，自修复组所造成钢筋锈蚀的加重并不会对钢筋的力学性能产生多大的影响，所以其对基体的影响可以忽略不计。而微生物自修复水泥基材料的主要优势在于能够实现更好的裂缝自修复效果，修复后裂缝区域的透水系数明显降低，能够更好地阻碍侵蚀物质向裂缝内部的传输，所以试件内部氯离子含量较普通水泥基材料内部氯离子含量更低，钢筋的腐蚀电流和自腐蚀电位负值更低且钢筋失重率更低，所以微生物自修复剂水泥基材料对裂缝进行修复后具有更好的护筋效果。

关键词： 微生物自修复；护筋性；氯离子侵蚀；碳化；杂散电流；

The Property and Mechanism of Protecting Reinforcing Steel Bar in Microbial Self-healing Cement-based Materials

Abstract

Concrete as the most popular civil engineering materials, have been widely used in all kinds of practical engineering. But when concrete cracks, those cracks can provide a convenient channel for aggressive substances to accelerate the process of internal corrosion of steel. The microbial self-healing cement-based materials can make cracks self-healing, and because it is simple, low cost, natural pollution-free, so there are more and more attention on it. At present, the study of microbial self-healing cement-based materials mainly focused on the mechanism of mineralization, the effect of crack repair and restoration of strength, but less study of the protection effect of steel bar. So the main study is focus on the property of protecting reinforcing steel bar in microbial self-healing cement-based materials and ordinary cement-based materials in chloride ion erosion environment, carbonation environment and stray current environment. Also with the test in condition of before cracking, before repair and after repair to compare the change of the property of protecting reinforcing steel bar.

The study found that the property of protecting reinforcing steel bar in microbial self-healing cement-based materials is not good as that of ordinary cement-based materials for the crack-free specimen, the microbial self-healing agent added to the substrate can weaken the resistance to chloride ion corrosion, anti-carbonation and anti-stray current slightly and also the worse electrochemical test results, so the actual corrosion conditions is more serious than that in the control group. The main reason is that the microbial self-healing agent has a certain air-entraining effect, so makes the macroporous matrix increase and reduces compaction rate of structure. But through the analysis of steel corrosion difference, we can find that the steel corrosion caused by self-healing group can’t have too much impact on the mechanical properties of steel, so its impact on the substrate is negligible. However the microbial self-healing cement-based materials can achieve better crack self-healing effect, the permeability coefficient of the repaired area decreased significantly and hinder the transmission of caustic substance to internal cracks better. So in the interior chlorine test, there are lower ion content than that of ordinary cement-based material and the corrosion current and negative corrosion potential are lower and the weight loss of reinforcement bars are less, so the microbial self-healing cement-based materials have better protection effect of steel bar after cracks been healed.

Key words: Microbial self-healing; Property of protecting steel bar; Chloride ion penetration; Carbonization; Stray current;

目录

摘 要 I

Abstract II

第一章 绪论 1

1.1混凝土开裂危害与裂缝修复方法 1

1.2混凝土自修复技术 1

1.3微生物自修复水泥基材料研究现状 3

1.3.1自修复机理研究现状 3

1.3.2混凝土环境中微生物活性研究现状 4

1.3.3微生物自修复剂对水泥基材料影响研究现状 6

1.3.4自修复效果研究现状 6

1.3.5护筋性研究现状 7

1.4本文主要研究内容与研究路线 8

第二章 试验原材料与测试方法 10

2.1 试验原材料 10

2.1.1 水泥 10

2.1.2 砂 10

2.1.3 钢筋 10

2.1.4 微生物自修复剂 10

2.2 电化学测试 10

2.2.1 试验设备 10

2.2.2 线性极化法 11

2.3 氯离子含量测定 12

2.3.1 试验设备 12

2.3.2 试验方法 12

2.4 标准碳化试验 13

2.4.1 试件制备 13

2.4.2 试验设备与方法 13

2.5 钢筋失重率测定 13

2.6 砂浆含气量测定 14

2.6.1 试验设备 14

2.6.2 试验方法 14

2.7 孔结构微观分析 15

2.7.1 试验设备 15

2.7.2 试验方法 15

第三章 裂缝制备与护筋性试验方法探究 16

3.1 裂缝制备方法探究 16

3.1.1 试件制备 16

3.1.2 三点抗弯法制裂缝 16

3.1.3 拉伸法制裂缝 17

3.1.4 钢片预置法制裂缝 18

3.2 氯离子侵蚀环境护筋性试验方法探究 19

3.2.1 试件制备与养护 19

3.2.2 氯离子侵蚀方法探究 20

3.3 碳化环境护筋性试验方法探究 22

3.4 杂散电流环境护筋性试验方法探究 22

3.4.1 试件制备与养护 23

3.4.2 杂散电流试验方法探究 23

第四章 护筋性对比试验结果与分析 24

4.1 氯离子侵蚀环境护筋性对比 24

4.1.1 电化学测试结果与分析 24

4.1.2 试件内部氯离子含量测定与分析 26

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