Water Repellent Treatment on Surface of Cement-based Materials

摘要

In many cases, service life of reinforced concrete structures is severely limited by chloride penetration until the steel reinforcement or by carbonation of the covercrete. Water repellent treatment ( WRT) on the surfaces of the cement-based materials has often been considered to protect concrete from these deteriorations. In this contribution three different types of water repellent agents have been applied, i. e. liquid silane, silane cream and si-lane gel, on the surfaces of concrete specimens. Penetration profiles of silicon resin in treated concrete have been determined by means of FT-IR spectroscopy. Water capillary suction, chloride penetration, carbonation and reinforcement corrosion tests have been conducted for the treated and untreated concrete samples. It turns out that surface impregnations reduce the coefficient of capillary suction of concrete by higher than 90 %. Consequently it restrains chloride ions from penetrating into concrete substantially. An efficient and reliable chloride barrier can be established by deep impregnation only. Water repellent treatments on the surface of concrete also lower the carbonation action under 70 % of relative humidity in this research. In addition it also has been found that surface impregnation with liquid silane can provide effective corrosion protection to reinforcing steel in the concrete with migrating chloride. The improvement of durability and extension of service life for reinforced concrete structures, therefore, can be expected through the applications of appropriate water repellent treatment.