Clinkering process and microstructure research on alite-sulfoaluminate portland cement clinker

Clinkering process and basic microstructure of Alite-sulfoaluminate Portland cement clinker had been studied. The result showed that Alite-sulfbaluminate Portland clinker can be clinkered at 1280 similar to 1320 degrees C. As well as C3S, beta-C2S, C(4)A(3)(S) over bar and C(4)AF formed, there will be some other minerals such as C(3)A, alpha'-C2S, CaSO4 and C(11)A(7).CaF2 formed in the clinker and the amount of Alite formed actually in the clinker will be much lower than that designed. During the burning, C(4)A(3)(S) over bar canbe formed below 1200 degrees C and the formation of C3S canbe nearly complete at 1300 degrees C. The temperature of liquid emerged at a great mass is about 1250 degrees C. When the burning temperature is higher than 1250 degrees C, C(4)A(3)S will decompose remarkably which is related to the volatilization of SO3. The emerging of liquid in the burning will accelerate volatilization Of SO3. In this kind of clinker, Alite crystals are with relatively large sizes and there are many inclusions of not only Belite crystals but also Alite in it. Crystals of C(4)A(3)(S) over bar emerged as a kind of greyish particles with hexangular or short pillar shape. Crystals of C(4)A(3)S lids a low Al2O3 content and a high Fe2O3 content, which indicated that C-4(A,F)(3)S has been formed actually in the clinker.