cement based permeable crystalline waterproof coating is a kind of gray powder waterproof coating, which is composed of 42.5 or more p.i or p.ii silicate rock cement and quartz sand as the base material and mixed with high active chemical substances. when it is applied on the concrete surface, the highly active substance contained in the product will rapidly free the unique active group r2 - under the excitation of free water, and dissolve and disperse in the water, in the presence of water a high concentration region of active group r2 - was formed on the surface of concrete. due to the existence of concentration gradient, the reactive r2 - group diffuses into the concrete matrix along the moisture content. due to the fact that there are a large number of hexagonal sheet ca (oh) 2 crystals in the hardened concrete paste, when the active r2 group meets the ca2 ions near the ca (oh) 2 crystal, the water-soluble complex ca2 - r2 - is formed, which increases the solubility of ca2 and promotes the dissolution of ca (oh) 2 crystal, the hydration product of cement.
the complex ca2 - r2 - will diffuse with water in concrete defects (such as pores and cracks). when sio32 - ions in the silicon rich area are encountered, sio32 - will replace the active group r2 - in the complex ca2 - r2 - and precipitate to form calcium silicate hydrate crystals. these crystals are constantly generated and grow, thus filling the cracks and pores in concrete. the unique active group r2 - is reduced to free radical again, and then circulates to complexate with ca2 and migrates to produce precipitation and crystallization.
once there is water, the above process can be cycled, and the osmotic crystallization activity will be activated, which can repair the concrete defects repeatedly and achieve permanent waterproof effect. in addition, the formation of complex ca2 - r2 - increases the apparent solubility of ca2 , thus further dissolving c3s and c2s in the unhydrated cement in the concrete matrix, continues to produce hydration reaction, and further blocks water seepage channels such as capillary pores and cracks, so as to further improve the impermeability of concrete matrix.