Studies On The Hybrid Of Organic Silicon-Inorganic Silicon As Concrete Surface Impregnating Agent

Almost all forms of concrete deterioration are caused by the ingression of the external corrosive media. Based on the principle of surface protection, if the water tightness and air tightness of surface layer concrete are improved and the internal transmission path of external erosion medium will be cut off. The method of concrete surface protection has become the key measure to improve the durability of concrete structure. The research and preparation of surface protective materials with excellent performance has great significance to improve the durability of concrete structure.In this study, TEOS sol and TEOS-PDMS hybrid sol were prepared respectively with sol-gel method under the effect of tartaric acid(TA) and dibutyltin dilaurate(DBTL) as the two kinds of catalytic system when ethyl silicate(TEOS) was used as inorganic precursor and hydroxyl silicone oil(PDMS) was used as organic hybridization agent. With two kinds of sol used as the concrete surface impregnating agents to deal with the cementitious materials, the stable performance and water resistance of two impregnating agents were characterized by the gel time, absorption and contact angle of cement base material; the hybrid process and water resistance mechanism of sol-gel were analyzed with FTIR spectra; according to the change rule of contact angle of treated cement base material that withstand ultraviolet aging and repeated washing, the weathering performance of hybrid impregnation agent was evaluated; The influence of the hybrid impregnation agent on the durability of concrete was studied through carbonation, freeze-thaw cycles and other durability tests. The research results show that:(1) The effect of catalysts on the water resistance after gel of TEOS sol impregnating agent is significant. Under the catalysis of TA acid catalyst, the hydrolysis degree of TEOS sol is bigger, the stable performance is better, the viscosity is smaller, and the permeability is better. When TEOS:TA=1:0.02, TEOS:H2O=1:2(molar ratio, the same below), the performance of TEOS sol is the best. The contact angle of the cement paste sample after treated by the TEOS sol is 76°, the water absorption rate decrease by 14.92%; under the catalysis of neutral catalyst DBTL, the degree of hydrolysis of the sol is smaller, the gel is more complete, and the water resistance is better. When TEOS:DBTL=1:0.02、TEOS:H2O=1:2, the performance of sol is the best. The contact angle of the cement paste sample after treated by the TEOS sol is 109°, the water absorption is decrease by 79.30%.(2) Compared with the TEOS sol, the introduction of hydrophobic groups, making the water resistance effect after gel of TEOS-PDMS hybrid sol has a significantly enhanced. Under the catalysis of TA, when add 30% PDMS, the cement paste specimen contact angle after impregnation treatment of TEOS-PDMS hybrid sol is 127°, water absorption rate decrease by 88.29%; Under the catalysis of DBTL, when add 40% PDMS, the cement paste specimen contact angle after impregnation treatment of TEOS-PDMS hybrid sol is 137°, water absorption rate decrease by 76.08%.(3) The penetration depth of TEOS-PDMS hybrid sol in concrete base material increases with the increase of the number of brushing times, and decreases with the increase of concrete strength. Compared with the DBTL, the initial viscosity of TEOS-PDMS sol under the TA catalyst is lower, and the penetration depth is greater. Ultraviolet aging and repeated washing test results show that the TEOS-PDMS sol under the TA catalyst has more excellent weather resistance.(4) TEOS-PDMS hybrid sol under the two catalytic systems can significantly improve the anti carbonization capability of Cement mortar specimen and the frost resistance of concrete. Under the catalysis of TA, TEOS-PDMS hybrid sol can show some anti water penetration ability when filling 0.3~0.9mm micro crack.