The Study On Recipe Optimization Of Cementitious Impermeability Composite Coating

Cementitious capillary crystalline impermeable coating characterized by its permanentwaterproofing effect, self-rehabilitating ability and environmental protection, was a new typeof cement-based waterproofing material which based on permeable crystallization action ofactive chemical substance to improved waterproofing effect of concrete. Bentonitecharacterized by its permanent waterproofing effect, resistance aging, lower cost,environmental protection and simple consturction and so on, was a kind of waterproofingmaterial high efficient which depend on water-welling property.In this thesis, the optimum dosage and mechanism of action of each component wereanalyzed which was based on the cementitious capillary crystalline impermeable coating ratioand parallel experiments. Cementitious capillary crystalline impermeable coating wasdeveloped by selected active chemicals and orthogonal experiments to optimize the dosage ofeach component to find the best ratio for performance testing, which compared to nationalstandards to finalize the formula. X-ray diffraction, scanning electron microscopy and otheradvanced testing method were used and explained from the micro to analysis cementitiouscapillary crystalline impermeable coating action mechanism, which can prove that capillarycrystalline improved the water impermeability of the substrate. According to the test resultsand microscopic analysis, the performance characteristics of the coating can be proved. Theoptimum contents of bentonite was detetmined by parallel experiments. The mechanism ofwater impermeability and the reason of strength drop are explanied from crystalline changeand microstructure.By analysis of eperimental dataes SEM and XRD, it show that the each componentoptimum active contents of Cementitious capillary crystalline impermeable coating are that:sodium silicate2%, ferric chloride1.5%, sodium dodecyl benzene sulfonate3%, aluminiummonostearate3%, Calcium hydroxide5%; Determined by parallel experiments, the1%bentonite was ideal dosage; The effect sequence of the component on performance and bestratio are that: cement55%, aluminium monostearate3%, sodium silicate2%, calciumhydroxide5%;28day impermeability pressure is1.5MPa and56day impermeability pressureis0.7MPa by performance testing.Water impermeability of the cementitious capillary crystalline impermeable coating wasbetter, strong penetration ability to the substrate specimen; Fibrous or needle-like crystals is formed in inside of the materials; The active substances can penetrate into the depth of50mmafter28days. Crystallization reaction can continue as long as the presence of water, thusmaking it self-healing capacity, long-term water impermeability, which can be proved by theimpermeability of the second pressure. The gel which was formed by water-swelling ofbentonite filled into gap lead to impermeability increasing and strength decreasing.