Study On Waterproofing Material Based Sulphoaluminate Cement

Because Portland cement has some shortcoming, such as slow hydration, shrinkage. Some admixtures are put in Portland cement in order to apply in waterproofing project. However, it leads to high cost and unstable quality. Sulphoaluminate cement has better properties than Portland cement, high strength, fast hardening, impermeability, corrosive resistance, frost resistance, expansive property and so on. It is suits for waterproofing building, but it is not sufficient for application with sulphoaluminate cement singly. Better impermeable effects are gained with mixing some agents.Sulphoaluminate cement mixing aluminum sulfate, ferric sulfate and ferrous sulfate or aluminum residue is studied in this paper. The main task and conclusion of this paper as follows:An optimal mixing amount of admixtures is confirmed through experiment. Some data are determined, which are setting time, compressive strength, expansion property, heat resistance, corrosive resistance, impermeability and frost resistance. With the help of XRD, SEM-EDS and DTA-TG, the cement hydration process is researched. Combing with the analysis of the porosity of hardening mortar, the reasons why the cement mixed agents is better than that without agents were explained further.The result shows that the optimal mixing amount of additives is 3%. They influence the early hydration process of sulphoaluminate cement clinker. The setting time of this material is shortened in 10 min. It has compressive strength in hours, and the 28d strength comes to 90MPa. Comparing with sulphoaluminate cement, the impermeability is improved. The height of permeable layer less than 2 centimeter after 120 hours under 2.0MPa water press. Simultaneously, some other properties are improved, such as corrosive resistance, frost resistance and heat resistance.Because the chemical composition of aluminum residue is so complex that some impurity, such as magnesium, can be found besides aluminum and ferric. The resultsof the cement mixing aluminum residue is worse than that mixing aluminum sulfate, even worse than sulphoaluminate cement.At the same time, through the study of the Interfacial Transition Zone in hardened mortar, we found take use of fine cement particle to coat the aggregate that can reduce the ITZ thickness and pore, increase dense effectively, optimize the structure that make compressive strength increasing and not make water after 150 hours under 1.0MPa water press, indicating excellent waterproof property.