Study of the relationship between scaling resistance and sorptivity of concrete

The aim of this study is to analyze the relationship between scaling resistance and sorptivity of concrete surfaces. Five types of air-entrained concretes containing cementitious materials (25%–35% fly ash, 25–35 slag, 1%–2% silica fume) were submitted to scaling tests according to ASTM C672 procedure, after 14 and 28 days of moist curing. These concretes were also submitted to sorptivity testing. Results show a clear correlation between scaling test results and sorptivity measurements. Low surface sorptivity (<0.1 mm/min1/2) always indicates satisfactory scaling resistance. These results show that to obtain adequate scaling resistance, curing conditions and mix design must be optimized to promote the development of a dense and impervious concrete skin that resists external water penetration. Lengthening of the moist-curing period of concrete incorporating cementitious materials systematically decreases sorptivity and improves its scaling resistance, especially for concrete containing fly ash.