Action mechanism for improving water impermeability of concrete surface based on deep penetrating sealer

Deep penetrating sealer (DPS) is water-based permeable crystalline waterproofing coating, and it is widely used to improve the impermeability and durability of cement-based materials. This study investigated the action mechanism of DPS on cement-based materials, especially the microstructure of the newly generated substances and pore evolution in concrete that DPS treated. To explore the action mechanism and permeability of DPS on cement-based materials, experimental specimens were fabricated in this experiment. The specimens included concrete, cement paste, dried DPS, and the product reacted by DPS mixed with saturated calcium hydroxide solution. To test the microstructure, chemical composition, pore structure, and macroscopic permeability of the specimens, scanning electron microscopy, x-ray diffraction, energy dispersive spectrometer, nitrogen absorption, and AutoClam equipment were employed. The experimental and analytical results showed that the calcium silicate hydrate content was increased by the chemical reaction between DPS and cement-based materials. The microstructure of concrete surface then became more densified. The volume of pore with a pore size ranging from 20 to 130 nm inside concrete was decreased, and the water penetration of the concrete was reduced by approximately 75%. This study revealed the action mechanism of DPS and cement-based materials, providing reference for the improvement of DPS and practical engineering application.