Water absorption behavior of hydrophobized concrete using silane emulsion as admixture

Abstract

Influences of silane emulsion as hydrophobic agent on pore structure of hardened cement paste (hcp), compressive strength and water absorption behavior of concrete were studied through pore structure analysis, water contact angle test and water/isopropanol absorption measurement. Results indicate that silane slightly inhibits early cement hydration and slightly reduces the 28-d compressive strength of concretes. The incorporation of silane significantly decreases the water sorptivity of concretes ascribed to the hydrophobization of capillary walls in hcps, whereas isopropanol absorption is not visibly affected by the addition of silane. The absolute water sorptivity decreases along with increasing water absorption amount for each group of concrete, which is believed to originate from swelling of C-S-H gel upon water absorption. However, the relative water sorptivity of the silane-modified concretes to the plain concrete remains constant during water absorption. A predicting method for long-term water absorption behavior of the silane-modified concrete is proposed.