Study On The Influence Of Mineral Composition On The Burning And Properties Of Alite-Sulphoaluminate Cement Clinker

This paper studied about the changes of the cement's hydration, setting properties and hardening behaviors caused by different content C₃S,C₄A₃(S|ˉ),C₄AF, using alite- sulphoaluminate cement made by pure chemicals and commercial raw materials in the laboratory. And the changes of the alite-sulphoaluminate cement's properties caused by different sintering temperature, sintering time, sintering atmosphere were also investigated.The results showed that, increasing the designed amount of C₃S, would harm the burnability of the clinker. When C₃S mineral content were 15%, 30%, 45%, 60%, the f-CaO content were about 0.23%, 0.23%, 0.29%, 1.95% respectively. In alite- sulphoaluminate cement mineral composition system, when the amount of C₃S designed was higher, it would restrain the formation of C₄A₃(S|ˉ), promote the strength development of the cement. Specificly, 3d's compressive strength were 18.50, 35.38, 43.94, 53.00 MPa, and the 28d's compressive strength were up to 70.69, 72.88, 83.88, 92.50 MPa, respectively. With the amount of C₃S increasing, the setting time of the cement were delayed remarkably. Specificly, the initial setting time were 47,82,94,98 minutes and the final setting time were 77,127,162,180 minutes.When the clinker with smaller content of C₄A₃(S|ˉ), the clinker becomes incompact and the burnability of the clinker was bad, when the designed amount of C₃S were 30%,45%,60%, with the amount of C₄A₃(S|ˉ) designed increasing, would form more C₃S. When the content of C₄A₃(S|ˉ) was smaller, the setting time of the cement was longer, with C₄A₃(S|ˉ) increasing, the setting time of cement changed to shorter. However, when the amount of C₄A₃(S|ˉ) was higher, the 3d's compressive strength was higher too, but the later compressive strength development was slowly.With the amount of ferrite phase increasing, the clinker was more compact and the burnability of raw mix improved, and that the formation of the major minerals C₃S and C₄A₃(S|ˉ) were promoted. If the amount of ferrite phase was too higher, the formation content of C₃S and C₄A₃(S|ˉ) decreased. Specificly, when the content of C₃S was 30%, 45%, a smaller amount of ferrite phase (<10%) could promote the formation of the major minerals C₃S and C₄A₃(S|ˉ). If the amount of ferrite phase was larger than 10%, C₃S and C₄A₃(S|ˉ) formation content decreased. However, the differences were, when the content of C₃S was 60%, a smaller amount of ferrite phase (5%) could promote the formation of the major mineral C₄A₃(S|ˉ); If the amount of ferrite phase was larger than 5.0%, C₄A₃(S|ˉ) formation decreased. With the amount of ferrite phase (<15%) increasing, the compressive strength of cement increased, the initial setting time and the final setting time would be delayed. While the amount of ferrite phase passed 15%, the compressive strength of cement would be lower.At the sintering temperature of 1320℃, the formation of the major mineral C₃S was better and the C₄A₃(S|ˉ) was at 1300℃. When the sintering temperature was 1320℃, the clinker with smaller C₃S designed would be form more C₄A₃(S|ˉ); In 1280℃, the major mineral C₃S and C₄A₃(S|ˉ) of clinker formed smaller. In higher temperature(1320℃,1300℃), the clinker with higher C4A 3S designed would form more C₃S mineral, while in the lower temperature, the results were on the contrary. In addition, with the temperature lowering, the setting time of the cement changed to shorter, the later 28d compressive strength lowed. When the C₃S content in less time (less than 30%), the 3d compressive strength of cement lowered gradually with increasing burning temperature. However, when the C₃S content was more than 30%, the early 3d compressive strength were higher when the burning temperature was 1300℃.In the oxidizing atmosphere, the main mineral of clinker can form better at 1300℃for 30 minutes, but in the reducing atmosphere and at higher sintering temperature and a longer sintering time were disadvantageous to the formation of main mineral. The compressive strength was higher and the final setting time was shorter that the cement clinker was sintered in oxidizing atmosphere than in reducing atmosphere.