海洋工程钢筋混凝土渗透型防护剂作用机理及纳米改性研究
发布时间：2018-08-13 19:23
【摘要】：在海洋环境中,钢筋混凝土因腐蚀破坏造成的经济损失难以估量,成为困扰全球海洋经济发展的难点问题,使得各国政府和企业投入大量资金用于钢筋混凝土耐久性与防护研究。在各类耐久性提升技术中,混凝土渗透型防护剂具有渗透成膜、有效防护、应用范围广等优势,受到极大关注。目前对渗透型防护剂的研究主要集中于混凝土宏观防护性能,在混凝土碳化、冻融及耐久性等方面作用机理仍不是十分完善,在实际应用中占有较大市场份额的硅烷防护剂还存在挥发量大、成膜时间长等问题。所以,针对渗透型防护剂作用机理及新型防护剂的研制开发显得尤为重要。本课题在综述海洋工程防腐技术及渗透型防护剂研究现状的基础上,首先通过混凝土湿度实验确定渗透型防护剂类型及混凝土基材处理要求；然后通过加速碳化实验和快速冻融实验丰富防护剂渗透成膜作用机理,并结合渗透型防护剂在混凝土碱性环境耐久性能研究,提出新型渗透型防护剂的技术需求；最后通过对硅烷渗透型防护剂进行溶胶凝胶酸碱两步法纳米改性,首次在混凝土防腐领域制备出快速成膜、有效防护的纳米改性硅烷渗透型防护剂。本课题主要工作及研究结论如下：(1)系统研究了不同混凝土湿度条件下渗透型防护剂成膜性能、渗透能力及防护性能的变化规律,研究发现：混凝土烘干处理时间越久则湿度越低,防护剂在混凝土中渗透深度越深、成膜时间越短,防护剂处理后混凝土氯离子电通量越低；随着烘干时间由6h延长到48h,防护剂在混凝土中的渗透深度增加1.8mm,成膜时间可缩短近36h,经防护剂处理混凝土的氯离子电通量值可以降低80%左右。(2)通过加速碳化实验研究了不同密实程度混凝土经渗透型防护剂处理后碳化深度的变化规律,研究发现：当混凝土密实程度较高时,渗透型防护剂可提高混凝土抗碳化性能,防护剂处理后混凝土碳化深度小于未处理试件；当密实程度较低时,渗透型防护剂会加速碳化进程,防护剂处理后混凝土碳化深度大于未处理试件。(3)通过快速冻融循环实验研究渗透型防护剂处理后混凝土质量损失和动弹性模量变化规律,研究发现：经渗透型防护剂处理的混凝土会在25次冻融循环时出现较大吸水增重过程,随着循环次数的继续增加,混凝土质量损失率会快速上升,并在125次冻融循环后混凝土出现2.7%的最大质量损失率；渗透型防护剂处理会加速混凝土相对动弹性模量下降,在125次冻融循环后混凝土相对弹性模量下降最大,达到51.3%。(4)通过户外服役实验研究了渗透型防护剂在早龄期混凝土上渗透深度和防护性能变化规律,研究发现：渗透型防护剂在早龄期混凝土碱性环境中渗透深度随着服役时间延长而小幅下降,其下降幅度会逐渐降低,最终使混凝土保持稳定的渗透深度值；尽管渗透深度会出现下降,所有渗透型防护剂处理砂浆都具备优异疏水效果,在整个户外服役阶段,24h表面吸水率都降低达90%以上。(5)采用溶胶凝胶酸碱两步法开展了纳米改性渗透型防护剂的合成与性能研究,研究发现：通过溶胶凝胶酸碱两步法实现酸性硅溶胶附着在碱性硅溶胶表面,制备出快速成膜、有效防护的纳米改性渗透型防护剂；以30nm碱性硅溶胶为原料按酸碱20：1比例在20℃C复合制备的纳米改性渗透型涂覆在混凝土试件4h后已基本成膜,比相同用量硅烷具有更好的降低氯离子电通量能力。
[Abstract]:In the marine environment, the economic loss of reinforced concrete caused by corrosion damage is hard to estimate, which has become a difficult problem to puzzle the development of the global marine economy. Many governments and enterprises have invested a lot of money in the durability and protection research of reinforced concrete. At present, the research on penetrating protective agent mainly focuses on the macro-protective performance of concrete. The mechanism of action in concrete carbonization, freeze-thaw and durability is still not perfect. Silane protective agent which occupies a large market share in practical application still has volatilization. Therefore, it is very important to study the mechanism of penetrating protective agent and the development of new type of protective agent. On the basis of reviewing the research status of marine engineering antiseptic technology and penetrating protective agent, the type of penetrating protective agent and concrete base material are determined by concrete humidity experiment. Physical requirements; then through accelerated carbonization experiments and rapid freeze-thaw experiments to enrich the mechanism of protective agent penetration film formation, and combined with the durability of permeable protective agent in alkaline environment of concrete durability study, put forward the technical requirements of new permeable protective agent; finally through the silane permeable protective agent sol-gel acid-base two-step method nanometer The main work and research conclusions of this subject are as follows: (1) The change rules of film-forming property, permeability and protective property of permeable protective agent under different concrete humidity conditions are systematically studied. The longer the soil drying time is, the lower the humidity is, the deeper the penetration depth of the protective agent in concrete, the shorter the film forming time is, and the lower the chloride ion electric flux of the concrete after the protective agent treatment is; with the drying time extending from 6 h to 48 h, the penetration depth of the protective agent in concrete increases by 1.8 mm, the film forming time can be shortened by 36 h, and the coagulation time after the protective agent treatment is shortened. The chloride ion electric flux of soil can be reduced by about 80%. (2) Through accelerated carbonization experiment, the change law of carbonization depth of concrete with different densities after treatment with penetrating protective agent is studied. It is found that penetrating protective agent can improve the carbonization resistance of concrete when the densities of concrete are high, and the concrete treated with protective agent can improve the carbonization resistance of concrete. Carbonation depth is less than untreated specimens; when the compactness is low, the permeable protective agent will accelerate the carbonization process, and the carbonization depth of concrete treated with protective agent is greater than untreated specimens. (3) The mass loss and dynamic elastic modulus of concrete treated with permeable protective agent are studied by rapid freeze-thaw cycles. The concrete treated with permeable protective agent will have a large water absorption and weight gain process during 25 freeze-thaw cycles. With the increase of the number of cycles, the mass loss rate of concrete will rise rapidly, and the maximum mass loss rate of concrete will be 2.7% after 125 freeze-thaw cycles. The permeable protective agent treatment will accelerate the relative dynamic elasticity of concrete. The relative elastic modulus of concrete decreases to 51.3% after 125 freeze-thaw cycles. (4) The penetration depth and protective performance of penetrating protective agent on early age concrete are studied by outdoor service experiments. The results show that penetrating depth of penetrating protective agent in alkaline environment of early age concrete changes with clothing. The decrease will gradually decrease with the prolongation of service time, and eventually the concrete will maintain a stable penetration depth. Although the penetration depth will decrease, all the penetration protective agents have excellent hydrophobic effect on the mortar. During the whole outdoor service period, the surface water absorption rate will be reduced by more than 90% after 24 hours. The synthesis and properties of nano-modified penetration protective agent were studied by two-step method of colloidal acid-base. The results showed that: acid silica sol was adhered to the surface of alkaline silica sol by two-step method of sol-gel acid-base, and nano-modified penetration protective agent was prepared quickly and effectively; 30 nm alkaline silica sol was used as raw material, and the acid-base ratio was 20:1. The nano-modified permeable coating prepared at 20 C for 4 hours has basically formed a film, which has better ability to reduce chloride ion flux than the same dosage of silane.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV33
本文编号：2181946
[Abstract]:In the marine environment, the economic loss of reinforced concrete caused by corrosion damage is hard to estimate, which has become a difficult problem to puzzle the development of the global marine economy. Many governments and enterprises have invested a lot of money in the durability and protection research of reinforced concrete. At present, the research on penetrating protective agent mainly focuses on the macro-protective performance of concrete. The mechanism of action in concrete carbonization, freeze-thaw and durability is still not perfect. Silane protective agent which occupies a large market share in practical application still has volatilization. Therefore, it is very important to study the mechanism of penetrating protective agent and the development of new type of protective agent. On the basis of reviewing the research status of marine engineering antiseptic technology and penetrating protective agent, the type of penetrating protective agent and concrete base material are determined by concrete humidity experiment. Physical requirements; then through accelerated carbonization experiments and rapid freeze-thaw experiments to enrich the mechanism of protective agent penetration film formation, and combined with the durability of permeable protective agent in alkaline environment of concrete durability study, put forward the technical requirements of new permeable protective agent; finally through the silane permeable protective agent sol-gel acid-base two-step method nanometer The main work and research conclusions of this subject are as follows: (1) The change rules of film-forming property, permeability and protective property of permeable protective agent under different concrete humidity conditions are systematically studied. The longer the soil drying time is, the lower the humidity is, the deeper the penetration depth of the protective agent in concrete, the shorter the film forming time is, and the lower the chloride ion electric flux of the concrete after the protective agent treatment is; with the drying time extending from 6 h to 48 h, the penetration depth of the protective agent in concrete increases by 1.8 mm, the film forming time can be shortened by 36 h, and the coagulation time after the protective agent treatment is shortened. The chloride ion electric flux of soil can be reduced by about 80%. (2) Through accelerated carbonization experiment, the change law of carbonization depth of concrete with different densities after treatment with penetrating protective agent is studied. It is found that penetrating protective agent can improve the carbonization resistance of concrete when the densities of concrete are high, and the concrete treated with protective agent can improve the carbonization resistance of concrete. Carbonation depth is less than untreated specimens; when the compactness is low, the permeable protective agent will accelerate the carbonization process, and the carbonization depth of concrete treated with protective agent is greater than untreated specimens. (3) The mass loss and dynamic elastic modulus of concrete treated with permeable protective agent are studied by rapid freeze-thaw cycles. The concrete treated with permeable protective agent will have a large water absorption and weight gain process during 25 freeze-thaw cycles. With the increase of the number of cycles, the mass loss rate of concrete will rise rapidly, and the maximum mass loss rate of concrete will be 2.7% after 125 freeze-thaw cycles. The permeable protective agent treatment will accelerate the relative dynamic elasticity of concrete. The relative elastic modulus of concrete decreases to 51.3% after 125 freeze-thaw cycles. (4) The penetration depth and protective performance of penetrating protective agent on early age concrete are studied by outdoor service experiments. The results show that penetrating depth of penetrating protective agent in alkaline environment of early age concrete changes with clothing. The decrease will gradually decrease with the prolongation of service time, and eventually the concrete will maintain a stable penetration depth. Although the penetration depth will decrease, all the penetration protective agents have excellent hydrophobic effect on the mortar. During the whole outdoor service period, the surface water absorption rate will be reduced by more than 90% after 24 hours. The synthesis and properties of nano-modified penetration protective agent were studied by two-step method of colloidal acid-base. The results showed that: acid silica sol was adhered to the surface of alkaline silica sol by two-step method of sol-gel acid-base, and nano-modified penetration protective agent was prepared quickly and effectively; 30 nm alkaline silica sol was used as raw material, and the acid-base ratio was 20:1. The nano-modified permeable coating prepared at 20 C for 4 hours has basically formed a film, which has better ability to reduce chloride ion flux than the same dosage of silane.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV33
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，本文编号：2181946
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