5TH International Congress on Technology - Engineering & Science - Kuala Lumpur - Malaysia (2018-02-01)

Effect Of Hydrophobisation On Durability Related Properties Of Concrete With Expanded Perlite

The paper is devoted to assessing the effectiveness of surface hydrophobisation concrete with perlite. The following laboratory tests were performed: density, porosity, absorptivity, capability to diffuse water vapor, frost resistance, contact angle. The Wu method was used for determining the SFE [1]. The composition of the one mixture of concrete was prepared: concrete with a 20% perlite instead of sand. Surface hydrophobisation was produced on the concrete using a methyl silicone resin and alkyl-alkoxy-silane in organic solvents [2]. The highest absorptivity after 14 days of testing was shown by concrete without an hydrophobic agent (18.4%), while the lowest absorption was demonstrated by the samples with methyl silicone resin (10.5%). The supreme hydrophobising effect on the concrete surface was shown by methyl silicone resin. The value of diffuse water vapor was 2.5 times smaller compared with the standard concrete. The hydrophobised concrete are characterized by an insignificant mass change due to freezing and thawing processes in the case of the methyl silicone resin – 0.4%, in the case of the alkyl-alkoxy-silane – 1.1%, the samples without hydrophobisation – 7.8%. Contact angle of standard concrete was smaller average 3 times than the angle of hydrophobic material, which indicates a very good hydrophobicity of the concrete with perlite. In the research presented in this paper, contact angle was about 39° of standard concrete and 104-123° of hydrophobic concrete (Figure 1). Figure 1. Contact angle of concrete hydrophobised with the alkyl-alkoxy-silanes. For the standard samples, the SFE value was the highest and is 99.43 mJ/m2. The lowest SFE value were obtained for alkyl-alkoxy-silanes – 13.54 mJ/m2. Hydrophobisation protect concrete surfaces against water and corrosion [1-4]. In the case of concrete with perlite, the hydrophobic layers limit the possibility of crystallized ice to move in the structure of the concrete, causing a reduction in their mass. The highest efficiency was obtained for the surface hydrophobised with the methyl silicone resin. The contact angle and SFE determine the wetting and adhesion properties of concrete with expanded perlite [1, 2, 5].
Danuta Barnat-Hunek, Marcin K. Widomski