混凝土用有机硅渗透剂耐紫外老化性能研究

处于恶劣环境中不加以保护的钢筋混凝土会发生腐蚀破坏，从而影响结构物耐久性。有机硅渗透剂是钢筋混凝土表面防护常见的物质。有机硅渗透剂由烷基烷氧基硅烷（或硅氧烷）组成，分子结构中的碳碳键、碳氢键键能低，均会被紫外辐照的能量破坏而断裂，从而失去憎水性。对涂布3种有机硅渗透剂(LS-A(BS1701), LS-B(70% BS1701 &30% BS290)和LS-C(异辛基硅烷膏体)）的砂浆试块进行了2 600 h耐紫外老化试验，通过跟踪记录涂布有机硅渗透剂砂浆试块的吸水率和表面疏水性的变化过程，以此间接反映有机硅渗透剂的耐老化性能。另外，通过研究紫外老化后经打磨的混凝土表面憎水性变化，探明紫外辐照对混凝土毛细孔内的有机硅渗透剂的影响。结果显示:与LS-A和LS-C相比，LS-B有机硅渗透剂具有最好的憎水性和耐紫外老化性能；LS-A和LS-C在老化600 h内吸水率和接触角变化较小；吸水率的变化趋势与接触角的变化趋势存在相关性；紫外老化2 600 h后的试块经表面打磨处理后，接触角有一定程度的恢复。根据试验结果可推测得出，硅氧烷主链上较多的小烷基数目有助于提升有机硅渗透剂的耐老化性能；硅烷的较大烷基则有利于有机硅渗透剂的初期耐老化性能；混凝土毛细孔内部的有机硅渗透剂基本没有受到紫外线的辐照影响。

Resistance to ultraviolet-light aging property of organosilicon impregnating agents for protecting reinforced concrete

Without any protection treatment, reinforced concrete shall be corroded in harsh environment, and the durability of concrete structure must decrease significantly thereby. The organosilicon impregnating agent is a common method for protecting the reinforced concrete against damage. It consists of alkyl alkoxy silane and/or siloxane. In the UV irradiation conditions, C-C and C-H bonds in the molecular structure will be destroyed due to low bond energy, and thus concrete loses hydrophobicity. In the study, three organosilicon impregnating agents (LS-A(BS1701), LS-B(70% BS1701 and 30% BS290) and LS-C(isooctylsilane cream)) were selected as the test materials to carry out a research on their properties of resistance to 2 600 h UV aging. By tracking the water absorption and surface hydrophobicity process of the organosilicon penetranting specimen mortar, the test results indirectly reflected the anti-aging properties of the organosilicone impregnating agents. In addition, the anti UV aging properties of the organosilicon impregnating agent in concrete pores were studied by surface polishing. The test results show that LS-B has the best resistance to UV aging properties. The water absorption increased slightly and the concrete surface is contact angle after treated with LS-A and LS-C as almost unchanged in the initial 600 h test time. The whole tendency of the contact angle decay and the water absorption increase is almost synchronous. When concrete surface polished after 2 600 h UV aging tests, the surface contact angle has a certain degree of recovery. According to those results, it can be expected that numerous small alkyl groups will be favorable to improving the anti-aging properties of the silicone penetrant; a larger alkyl group is beneficial to the early anti-aging properties; and the UV aging has little influence on the organosilicon impregnating agents in the concrete pores.