| Since sulphoaluminate cement mass production, the annual output has been increasing in our country. As one of four varieties of special cement, it has been widely used in concrete expansion agent and repair engineering materials of concrete. Itself has many excellent properties, such as early strength, high strength, rapid hardening, low alkali, freezing-thawing resisting, low permeability, creep and corrosion resistance,etc.The raw material of sulphoaluminate cement is bauxite, limestone and gypsum, clinker minerals are mainly formed by anhydrous calcium sulphoaluminate, dicalcium silicate and iron phase after sintering. In the paper combining local businesses bauxite containing more Fe2O3, we can burn out of acceptable quality cement in the laboratory, so that enabling the use of low-grade bauxite, to reduce production costs and improve efficiency in the use of resources. Experiment with different Fe2O3 content and sintering temperature to burn sulfur cement clinker, we have analyzed and studied its effect on clinker burning system and mineral crystals. We made a preliminary exploration of the impact on the physical properties and the degree of hydration of cement, and to provide information and guidance for the actual production of cement companies.We can obtain the following conclusions from the appearance morphology analysis, petrographic analysis and XRD analysis of the sintered clinker. With the increase of Fe2O3 content, the color of clinker sample from gray or gray-black soil deepening to dark, the liquid phase and hardness increases.When the iron content is 12%, the crystal size of clinker mineral is the smallest and the crystallization degree is the poorest. The increase of iron content in clinker make sintering temperature drop and sintering temperature range does not change obviously. Reducing the 2C2S·C S and f-Ca O content in the clinker mineral with the increase of Fe2O3 content and promoting the absorption and conversion of unfavorable components in the clinker minerals.After adding 8% of gypsum and clinker grinding together, we have studied the iron oxide content and sintering temperature on the physical properties of cement and degree of hydration by the cement setting time, compressive strength, bound water content and p H, and carried out on the hydration products of XRD and SEM analysis. The results show that the early and late compressive strength are higher than the other components and the setting time can also meet the requirements when the iron content is 8% and sintering temperature is 1350?. With the increase of Fe2O3 content, bound water content of cement have a downward trend in all ages, and the hydration rate of cement is gradually decreased. After the cement hydration, p H is increased with the increase of Fe2O3 content in the material and showing a tendency to decrease the first and then increases. Microscopic analysis showes that the main material of cement hydration is the iron glue, ettringite, AFm and a small amount of calcium silicate hydrate gel flocculent,which cemented together with each other to form the space structure of cement paste. |
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