双功能铝酸钙改性硅溶胶钢筋涂层

Bifunctional Calcium Aluminate Modified Silica Sol Coating for Reinforced Bar

制备了一种用于混凝土结构中钢筋表面腐蚀防护的硅溶胶涂层,以水玻璃为前驱体,在涂层制备中引入铝酸钙填料,研究了铝酸钙(C3A)不同添加量对涂层防护性能的影响。采用XRD、FT-IR、SEM、离子色谱仪以及电化学测量技术对C3A及水化物的结构形貌、离子交换能力、涂层的结构形貌及腐蚀防护性能进行表征。结果表明,铝酸钙在涂料制备中可以水化形成LDH,且水化后的LDHs具有的阴离子交换功能,可吸附腐蚀介质中的侵蚀性Cl-。同时LDHs本身的片层状结构有助于缓解涂层固化过程中产生的内应力,消除涂层产生的开裂,且可有效提高涂层的阻隔性能,减缓Cl-等侵蚀性离子到达钢筋表面的速率,进而提升硅溶胶涂层对钢筋腐蚀的防护性能。

A silica sol coating for corrosion protection of reinforce bars in concrete structures was prepared via mechanical blending and ultrasonic dispersion with water glass as the film precursor and calcium aluminate as filler.Then the effect of different amounts of calcium aluminate addition on the protective performance of the coating was studied.The structural morphology and ion exchange ability of calcium aluminate and its hydrates,as well as the structural morphology and protective performance of the coating were characterized by XRD,FT-IR,SEM,ion chromatograph analysis and electrochemical measurement.The results indicate that calcium aluminate can be hydrated to form LDH during the coating preparation,thus due to their anion exchange function,LDHs can absorb corrosive chloride ions from corrosive media,meanwhile,the layered structure of LDHs may be benefit to alleviate the internal stress generated during the coating curing process,in turn,eliminate the cracking in the coating and improve effectively the barrier performance of the coating,while slow down the infiltration rate of chloride ions and other corrosive ions reaching the surface of the steel bar,eventually enhance the protective performance of the silica sol coating against the steel bar corrosion.