2022 Volume 76 Issue 1 Pages 365-371
This paper deals with the effect of surface treatment by water-absorption-controlling materials on the carbonation resistance of polymer-modified mortar coated concretes. Two types of the polymer-modified mortars are prepared with the polymer-cement ratios of 0 and 5％ as coating mortars for base concretes. The base concretes with water-cement ratio of 57.9％ are also prepared, and cured under prescribed conditions for 28d. The base concrete surface is treated by wetting and the water-absorption-controlling materials with the application quantity of 20, 25 and 30g/m2 as solids. Then the base concretes are coated by the polymer-modified mortars with coating thickness of 2.5mm, and cured under prescribed conditions for 28d. The polymer-modified mortar, base concrete, water-absorption-controlling material coated concrete, and polymer-modified mortar coated concrete specimens are stored in the carbonation chamber with 30℃, 60％（RH） and CO2 concentration of 5％. Except for the polymer-modified mortar coated concrete specimen, the carbonation depth of the specimens is measured at storage periods of 28, 56 and 84d. The carbonation depth of the base concretes of polymer-modified mortar coated concretes are also measured at storage periods of 28, 56 and 84d after complete carbonation of the coated polymer-modified mortar layer. As a result, the carbonation resistance of the base concrete is improved by applying the water-absorption-controlling material to the base concrete. The polymer-modified mortar layer still inhibits CO2 penetration after the layer is completely carbonated. Such carbonation resistibility of the polymer-modified mortar layer and by the application of the water-absorption-controlling materials improve the carbonation resistance of the base concrete coated with the polymer-modified mortar.
