Effect Of Sintering Condition On High Cementing Property Cement Clinker And Alite Crystal Structure

Cement, as the major component, is the critical material that can determine concrete performance. Nowadays, concrete is developing in the trends which are high property, low energy consumption, fine durability and answering for the development of ecology well, etc. Only when cement is provided with the properties—high strength and fine durability and low environment loading, it can come up with this trend of concrete development. There are so many influencing factors can affect cement clinker, and the burning condition is one important factor among them. In order to research the relation between burning condition and the mineral composition and properties, structure and performance of clinker, the effect of burning condition on burning of high cementing property cement clinker was studied in this thesis.The results of research show that, enhancing burning temperature and extending holding time properly is in favor of Alite generation, and it can reduced the content free-calcium (abbreviate to f-CaO). In C₃S doped foreign substance properly, in particular, doped with fluorine and phosphorus or slag of phosphorus, free-calcium (abbreviate to f-CaO ) content could be reduce further and Alite crystal is more regular. Reducing atmosphere and cooling slowly were harmful to clinker burning. In the clinker burn in reducing atmosphere and cooling slowly, compared to the clinker burn in oxidizing atmosphere and cooling quickly, Alite content was reduced and its crystal was irregular, a large number of foreign substances were encapsulated in the Alite crystal, and f-CaO content rose at the same time.C₃S and its solid solution were prepared by Sol-Gel method. The pure C₃S crystal is T structure in room temperature. Foreign substance can make the crystal high temperature structure stabilized in room temperature. If doped 1.5% CaF₂ in pure C₃S, the C₃S crystal became M structure. When the CaF₂ content more than 2.0%, the C₃S crystal became R structure in room temperature. When the content of CaF₂ was 0.7¹.4% and CaHPO₄ was 0.4⁰.8%, the C₃S crystal was R structure in room temperature. When the Al₂O₃, Fe₂O₃, MgO, K₂O, Na₂O were introduced into pure C₃S at the same time, the C₃S crystal became M structure. If doped 0.7%CaF₂ and 0.4%CaHPO4 in this C₃S crystal, the C₃S crystal was R structure in room temperature. In the clink, none doped, Alite crystal was M structure in room temperature. When clinker doped with fluorine and phosphorus or slag of phosphorus, Alite crystal were M structure and R structure concomitant in room temperature.Burning system could affect the crystal structure of C₃S solid solution and its hydration activity. C₃S solid solution, in the clinker cooled quickly, present as R structure, M structure or the two structures concomitant, and its hydration activity was high. When clinker cooled slowly, C₃S solid solution stability is reduced and changed to T structure, partial C₃S solid solution decomposed to and f-CaO. This lead the C₃S solid solution content reduce and hydration activity deteriorate. If the clinker was burn in reducing atmosphere, it could aggravate this change of the structure.Cement clinker property was related to the content of Alite and its microstructure. The higher Alite content was, the strength was higher. On the contrary, the strength was debased (3days, 28days). When the Alite was present as R structure and M structure or the two structure concomitant, the clinker hydration activity is high. When C₃S structures present as T structure, the hydration activity debased.The C₃S structures were analyzed with the Rietveld method, the results shows that structural parameters of pure C₃S with T structure were a=11.637(?), b=14.213(?), c=13.687(?),α=105.3°,β=94.6°,γ=89.9°, V=2177(?)3; Z=18. In clinker, structural parameters of C₃S with M structure were a=33.089³3.166(?), b=7.045⁷.057(?), c=18.536¹8.581(?),β=94.1⁹4.3°, V=4310⁴336(?)3; Z=36, structural parameters of C₃S with R structure were a=7.057⁷.078(?), c=24.984²5.074(?), V=1078¹088(?)3; Z=9, and structural parameters of C₃S with T structure were a=11.647¹1.650(?), b=14.248¹4.250(?), c=13.740¹3.748(?),α=105.6¹05.7°,β=94.3⁹4.4°,γ=90.2°, V=2189²192(?)3; Z=18.