Investigation of Silane Impregnation for Protection of Alkali-Activated Slag Mortar

This paper investigated the effects of silane impregnation on the protective properties of alkali-activated slag (AAS) mortars. The surface silane impregnation on water absorption, contact angle, and penetration depth were examined. The related protective mechanism regarding silane impregnation was analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier infrared spectroscopy (FT-IR). The results showed that the surface of the AAS mortar after silane impregnation was transformed from hydrophilic to hydrophobic with an increased contact angle of 80° from 36° to 116°. And the water absorption was significantly decreased by 74.42% to 97.79%. The penetration depth of the two-layer coating was dramatically higher than that of the one-layer coating. The optimal coating method and dosage of silane were two-layer coating and 200 g/m2. In addition, silane impregnation formed a stable Si-O bond with AAS mortars through a hydrolytic condensation reaction and the −CH2CH3 group of the silane acted on the surface of the AAS mortars.