In this study, three types of concrete surface penetrant materials were studied in the laboratory environment, including two kinds of silicate solutions (modifying and reaction type), and another hydrophobic impregnating material silane. They were painted on two different cement-based (Normal Portland cement and Blast furnace slag) concrete. During the experiment, there were three sorts of painting schemes, consist of two kinds of silicate applied separately and a compound application of silicate reaction type and silane type. Five kinds of painting dosage were designed, which were the recommended dosage, and 0.25, 0.5, 1.0 and 2.0 times of the recommended dosage. The surface air permeability and water absorption rate of the concrete before and after painting penetrants were tested and compared. It found that all of them have little effect on air permeability, however, the air permeability of the concrete surface decreased with the increase of the surface water content. But the water absorption rate was not affected by surface water content obviously when it was 4 - 5%. The composite coating method could significantly reduce the surface water absorption rate of concrete, and the dosage was also much more economical.
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