Study On Synthesis, Composition, Structure And Performance Of Alite-C_2.75B_1.25A₃(?) Cement Material

With development of society, more and more shortcoming and flaw is emerged out using large number of Portland cement. For example, Portland cement has lower early strength and shrinkage flaw at the hardening course, which affecting process of the engineering, stability or durability of the concrete and application range of the Portland cement. Additionally, producing Portland cement cost lots of energy, consume a great deal of limestone resource, letting out large number of CO₂ and NO_x polluting atmosphere greatly. Synthesizing new type of high property cement material by mineral compounding is one of the measures to solve problem listed above.Since a single constituent mineral named barium calcium sulphoaluminate (3CaO·3Al₂O₃·BaSO₄) has been synthesized in laboratory successfully, many scientists concern the mineral. Result indicates that the mineral constituted C₂.75B_1.25A₃ S has optimal strength, its compressive strength at 1d, 3d, 28d comes to 35.1MPa, 59.3MPa and 72.1MPa respectively. Therefore, barium calcium sulphoaluminate as main mineral of barium bearing sulphoaluminate cement has prominent early strength, fast hydration rate and short setting time, but its improving rate of the late strength is small. On the contrary, Alite as dominant mineral of Portland cement has lower early strength and longer setting time, its improving rate of the late strength is higher than barium bearing sulphoaluminate cement. The experiment is to establish higher adhesive mineral phase system, which named Alite - barium calcium sulphoaluminate cement at the base of the two minerals.Clinker composition and sintering technology were picked out and optimized by using orthogonal test design and theory of material thermodynamics. Because material thermodynamics can only solve trend of mineral phase reaction, when clinker composition was been optimizing, mechanics performance of cement, current industrial producing practice and Gibbs free energy of mineral phase reaction were integrative considered. At the base of the optimizing composition, excessive amount of SO₃ and BaO was mixed into the clinker system to compensate SO₃ and BaO volatilization or solid phase dissolution. According to the analysis of f-CaO and mechanics performance, suitable amount of CaF₂ in the clinker system was chosen out. Finally, utilizing industrial raw material to prepare the optimal constituent cement clinker. With help of modern test techniques, such as XRD, SEM-EDS, DTA-TG and Lithofacies analysis, the clinker composition, structure and...