The Research of Hydrolysis Test of Silicone Water Repellent for Protecting Reinforced Concrete

Abstract

It is one of the measures of improving durability of concrete structure that apply silicone water repellent on concrete surface. The characteristic of silicone water repellent is to keep the respiratory function of concrete, not to change the original appearance of the concrete, have good hydrophobic performance and can resist to chloride ion penetration. This paper studies the hydrolysis of silicone water repellents solutions with different pH by measuring the electrical conductivity, pH value, and surface tension of the solution. The results show that silicone water repellent is hydrolyzing quickly very much. The hydrolysis time will extend with the increase of the concentration of silicone water repellent. By means of impregnating sand, rubble, cement pieces and calcium carbonate (CaCO3) powder with silicone water repellents, the water absorption at different temperature and humidity are studied and compared with the same material but not impregnated. The results indicate that the water absorption of impregnated material decreases and the silicone water repellent has hydrophobicity. The higher humidity can help hydrolysis and adhesion of silicone water repellent. The higher temperature may increase water absorption of base materials impregnated with low molecule weight silicone water repellent. Low molecule weight silicone water repellent liquid is residue on the calcium carbonate powder surface.