Preparation And Performance Of Calcium Sulpho-aluminate Modified Portland Cement

MgO exists in the clinker as minor component. The addition of MgO with proper amount can lower the formation temperature of liquid phase, decrease the liquid phase viscosity and surface tension. Inaddition, the amount of liquid phase increases. MgO is beneficial to the formation of clinker. However, free periclase appears when the addition is exceeded. Delayed expansion of periclase can impair the soundness of cement.Calcium sulpho-aluminate modified Portland cement is the compound of the mineral of calcium sulpho-aluminate and the mineral system of Portland cement clinker, which has the main excellences both of alite and calcium sulpho-aluminate minerals. The sintering temperature of Calcium sulpho-aluminate modified Portland cement is low. The SO₃ can decrease the pernicious effect of MgO when the content of MgO is higher. In this paper, emphasis is payed on the study of the burnability of raw meal, the shaping of clinker mineral and the performance of the clinker. MM, XRD, DTA, ESEM and EDAX are used to investigate the role of MgO in calcium sulpho-aluminate modified Portland cement clinker formation and performance.The results show that CaF₂ can improve the burnability of raw meal, and benefit to the coexistence of the minerals of C3S and C₄A₃(S|ï¿£). Within the content of CaF₂ in this test, the optimal addtion content is 0.5%. MgO can decrease the formation temperature of liquid phase, but it can not make the minerals of C3S and C₄A₃(S|ï¿£) coexist in the clinker.The amount of periclase increases with the increase of MgO content. Periclase in the clinker exists mainly around the hole. Periclase generally growth with the intermediate phase, the most size of the periclase is 1⁴μm. With the increasing content of MgO in clinker, cement setting time, strength is decreased.