EFFECT OF SURFACE TREATMENT OF CONCRETE BY WATER-ABSORPTION-CONTROLLING MATERIALS ON CHLORIDE ION PENETRATION RESISTIBILITY OF POLYMER-MODIFIED MORTAR COATED CONCRETES

<p>This paper deals with the effect of the surface treatment of a base concrete by water-absorption-controlling material （WACM） on the chloride ion penetration resistibility of polymer-modified mortar （PCM） coated concretes. PCMs using the EVA and AME emulsions are prepared with the polymer-cement ratios （P/C） of 0 and 5％ as coating mortars for the base concrete. The specimens of the base concrete with water-cement ratio of 57.9％ are prepared, and cured under prescribed conditions for 28d. For preparing the WACM coated concrete specimens, the surface of the base concrete specimens is treated by the EVA- and AE-WACM with the application quantity of 20, 25 and 30g/m² as solids which are the range of the recommended application value of productors. Then the specimens are subjected to dry curing for 1d. For preparing Plain and PCM coated concrete specimens, the surface of the base concrete specimens is treated by wetting with the water or the WACMs with the application quantity of 20, 25 and 30g/m² as solids. After such treatment of the concrete surface, the base concrete specimens are coated by PCM with coating thickness of 2.5mm, and cured under prescribed conditions for 28d. The specimens of base concrete, WACM coated concretes, PCM coated concretes are immersed in salt water. The chloride ion penetration depth of the base concrete and WACM coated concrete specimens is measured at immersion periods of 28, 56 and 84d. In PCM coated concrete specimens, the measurement of the chloride ion penetration depth of the base concretes is started after the complete penetration of chloride ion into the coated layer of PCM during the immersion. The chloride ion penetration depth measurement of PCM coated concrete specimens is conducted at the immersion periods of 28, 56 and 84d from such starting point. As a result, the chloride ion penetration resistibility of the base concrete is improved by the surface treatment by WACM coating. After the chloride ion is completely penetrated into PCM coated layer of PCM coated concrete specimens, the layer still inhibits the chloride ion penetration into the base concrete. The ability of the surface treatment by WACM and PCM coating is increased with an increase in the application quantity of WACM. The chloride ion penetration resistibility of the concrete is considerably improved by the synergy of the application of WACM as the concrete surface treating material and PCM coating for the concrete.</p>