混凝土用硅烷类防护材料的制备及其对混凝土耐久性影响

发布时间：2018-05-30 18:08

本文选题：硅烷 + 防水　；参考：《青岛理工大学》2014年硕士论文

【摘要】：钢筋混凝土被广泛使用的同时，其耐久性问题也越来越受到重视，，混凝土耐久性下降大多与水的作用有关。混凝土用防护材料种类甚多，其中的硅烷类材料自身表面张力低，有杰出的渗透能力，在涂覆于混凝土表面之后，能够舒展并渗透进入混凝土一定深度范围内，并在毛细孔壁表面形成烷基憎水薄膜，降低混凝土基材的表面能，使混凝土表面由亲水性变为疏水性，阻止水分的侵入，同时保持混凝土的透气性，赋予混凝土裂缝防护能力；而且硅烷类材料自身耐久性好、抗紫外线性能优秀，基材的外观在涂覆后几乎不受影响，其优秀的防护性能受到了广泛的关注。本文以乙烯基三乙氧基硅烷、乙烯基三甲氧基硅烷、甲基三乙氧基硅烷、辛基三乙氧基硅烷、异丁基三乙氧基硅烷等硅烷单体为原料，对制备过程进行了研究，主要包括制备硅烷聚合物的引发剂用量、反应时间、温度，以及制备硅烷乳液的方法、反应温度、乳化剂配比等。通过自由基聚合和硅烷乳化分别制备了硅烷聚合物和硅烷乳液，并研究了硅烷单体、硅烷聚合物、硅烷乳液对不同水灰比（0.4、0.5）的混凝土耐久性能的影响。试验项目包括：毛细吸水试验、毛细吸盐试验、氯离子渗透系数和渗透深度、加速碳化试验、快速冻融试验、硫酸盐侵蚀试验。结果表明，表面涂覆聚乙烯三乙氧基硅烷的混凝土，氯离子扩散系数仅为1.1×10-12m2·s-1，毛细吸水系数比未处理的混凝土降低了87%以上，硅烷单体也能使吸水系数降低85%以上，硅烷乳液效果较差，吸水系数降低77%~85%，在防护要求不苛刻的工程中，可以用硅烷乳液代替硅烷单体。同时硅烷聚合物在加速碳化实验、快速冻融试验、抗硫酸盐侵蚀试验中也有很好的效果，聚乙烯三乙氧基硅烷能将0.5水灰比的混凝土28天碳化深度降低88%，而且使混凝土有很好的抗冻性，抗硫酸盐侵蚀试验中有最稳定的效果；而硅烷乳液在不同的试验条件下的试验结果却很不稳定。试验结果为工程实际中对硅烷单体、乳液和聚合物的选择和使用提供了参考。硅烷材料能够不同程度地提高混凝土的耐久性，在国内外桥梁、公路等工程中得到了广泛的应用。硅烷单体渗透深度深，有效成分较高，有着较好的防护效果，但挥发性大、有毒性等缺点阻碍了其广泛应用。硅烷乳液的防水效果虽然稍逊于硅烷单体，但是其稳定性好、挥发率低、毒性小。硅烷聚合物虽然渗透深度较小，但是自身耐久性好，而且在各种试验中得出稳定、出色的防护效果。结果表明，本课题自主制备的硅烷材料能够明显降低混凝土的吸水系数，提高抗氯离子、抗硫酸盐、抗碳化与抗冻融的能力。
[Abstract]:With the widespread use of reinforced concrete, more and more attention has been paid to the durability of reinforced concrete. The deterioration of concrete durability is mostly related to the effect of water. There are many kinds of protective materials for concrete, among which silane materials have low surface tension and excellent permeability. After coating on concrete surface, they can spread and penetrate into a certain depth of concrete. The alkyl hydrophobicity film is formed on the surface of the capillary wall to reduce the surface energy of the concrete substrate, so that the surface of the concrete changes from hydrophilicity to hydrophobicity, which prevents the water from invading, and at the same time keeps the permeability of the concrete and endows the concrete with the ability of crack protection. Moreover, silane materials have good durability, excellent UV resistance, and the appearance of the substrate is almost unaffected after coating, and its excellent protective performance has been paid more and more attention. In this paper, the preparation process of silane monomers, such as vinyl triethoxy silane, vinyl trimethoxy silane, methyl triethoxy silane, octyl triethoxy silane and isobutyl triethoxy silane, was studied. It mainly includes the amount of initiator, reaction time, temperature, the method of preparing silane emulsion, reaction temperature, emulsifier ratio and so on. Silane polymer and silane emulsion were prepared by free radical polymerization and silane emulsification, respectively. The effects of silane monomer, silane polymer and silane emulsion on the durability of concrete with different water-cement ratio (0.4g / 0.5) were studied. The test items include capillary water absorption test, capillary salt absorption test, chloride ion permeation coefficient and penetration depth, accelerated carbonization test, rapid freeze-thaw test and sulfate erosion test. The results show that the chloride diffusion coefficient of the concrete coated with polyethylene triethoxy silane is only 1.1 脳 10-12m2 s-1, the capillary water absorption coefficient is more than 87% lower than that of untreated concrete, and silane monomer can also reduce the water absorption coefficient by more than 85%. The effect of silane emulsion is poor, the water absorption coefficient is reduced by 77% and 85%. In the engineering with low protection requirements, silane emulsion can be used instead of silane monomer. At the same time, silane polymers also have good results in accelerated carbonation test, rapid freeze-thaw test and sulfate corrosion resistance test. Polyethylene triethoxy silane can reduce the carbonation depth of 0.5 water-cement ratio concrete in 28 days by 88%, and make the concrete have very good frost resistance, and it has the most stable effect in the sulfate corrosion resistance test. However, the test results of silane emulsion under different experimental conditions are very unstable. The experimental results provide a reference for the selection and application of silane monomers, emulsions and polymers in engineering practice. Silane materials can improve the durability of concrete in varying degrees, and have been widely used in bridges, highways and other projects at home and abroad. Silane monomer has deep permeation depth, high effective component and good protective effect, but it is widely used because of its high volatility and toxicity. The waterproofing effect of silane emulsion is inferior to that of silane monomer, but its stability is good, volatilization is low and toxicity is small. Although the penetration depth of silane polymer is small, its durability is good, and stable and excellent protective effect is obtained in various tests. The results show that the self-made silane material can obviously reduce the water absorption coefficient of concrete and improve the ability of resisting chloride ion, sulfate, carbonation and freezing and thawing.
【学位授予单位】：青岛理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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