2018 Volume 29 Pages 11-19
In order to inhibit water penetration into concrete, hydrophobic surface impregnation is generally used to protect concrete, but there is concern that water repellency may decrease greatly when cracks occur. This study aims to develop an internal hydrophobic cementitious material by mixing several hydrophobic agents. Two mixing methods of the agents, direct mixing and sand spraying, were carried out. It was found that mortar with sand sprayed with silicone-based agent had a relatively high contact angle and hydrophobicity under wetting and drying cycles even if cracks occurred, although compressive strength decreased to some extent. Further, mortar with the addition of an alkyl-modified siloxane agent could greatly inhibit the water penetration after partial drying, and drying shrinkage was also found to be smaller than that of normal mortar.
