Study On Cementitious Capillary Crystalline Waterproofing Materials

The leakage problem of ordinary concrete has plagued researchers in the field of civil engineering for many years.The traditional waterproof material is prepared mainly through the formation of waterproof layer by using flexible waterproof material to meet the need of waterproof,but the poor durability and low efficiencies limited their real practical application.In recent years,rigid waterproof material,namely,the cementitious capillary crystalline waterproof material,has shown irreplaceable advantages in the field of civil engineering own to its permanent waterproofing,simple construction and good waterproof effect.However,the preparation technologies and key components of the rigid waterproof material mainly rely on foreign imports,resulting in higher product costs,eventually seriously restricting the further development of these materials.The purpose of this project is to develop a kind of cementitious capillary crystalline waterproof material with good effect of penetrating and crystallizing to gain better waterproof performance by comparison with the same kind of domestic and foreign products,which was in accordence with national standard.This paper studies the internal structure of concrete and the mechanism of cementitious capillary crystalline waterproof material to explore the active substances that can penetrate into the concrete pores and produce stable crystal.Using orthogonal design to find the optimum mix ratio of active substances in cementitious capillary crystalline waterproof material.Testing various performance of the material and studying the effect of the different age on the waterproof performance.Analyzing the morphology,crystallized product,depth of penetration and performance of the as-prepared waterproof material by scanning electron microscopy and X-ray diffraction patterns.Through the experimental study to obtain cementitious capillary crystalline waterproof material with better performance indicators than the national standard GB18445-2012 and analyze the economic and social benefits of this materials.The results show: 1)Optimum mix ratio of active substances for magnesium calcium carbonate,sodium sulfate,sodium silicate,active material B and other additives is 13%,42%,3%,7% and 10%,respectively.The main factors affecting the waterproof performance of the material is magnesium calcium carbonate,followed by sodium silicate,active B and sodium sulfate.2)The appearance,moisture content,fineness,chloride ion content,construction,flexural compressive strength,wet base surface bond strength,impermeability and other performance indicators of self-developed waterproof material are all in line with national standards.3)The secondary impermeability of concrete with waterproof coating is large indicating the cementitious capillary crystalline waterproof material has a secondary repair effect on the concrete.We can also discover that the removal of the waterproof coating specimen has good impermeability,indicating that the active material in the waterproof material can penetrate into the inside of the concrete to produce insoluble crystals,which can clog the pores and cracks and make the concrete more dense.4)Through the study of the test block of different ages,it is found that the effect of the active substance on the 3 day test block is better than that of the 7 day,the 14 day and the 28 day.5)From the X-ray diffraction analysis,it is found that the main peak of the diffraction of the crystal product is mainly calcium carbonate.6)The results of scanning electron microscopy show that there are a large number of needle-like crystals in the pores and cracks of the waterproof coating test piece.The needle-like crystals may be comprised of calcium silicate hydrate,calcium carbonate or ettringite and other substance are formed by the reaction between the active substance in the waterproof material.The active substance can penetrate to the substrate at least 20 mm depth of the test piece.Through the analysis of the economic and social benefits of the cementitious capillary crystalline waterproof material,it is found that the material has high application value.