Study On Preparation And Mechanical Properties Of Composite Cementitious Material Of Converter Steel Slag And Electrolytic Manganese Slag

Steel slag is a solid industrial waste discharged in the process of steelmaking,which has a large amount of emissions and low utilization rate.From the chemical composition,the steel slag is rich in CaO,SiO₂,Al₂O₃ and Fe₂O₃ and so on,which is similar to that of clinker,but from the point of view of cementitious activity,the steel slag cementitious activity is much lower than that of clinker,which leads to the limited utilization of steel slag.The converter steel slag is the most common steel slag,and the converter steel slag is about 70%of the steel slag emission.Electrolytic manganese slag is from industrial solid waste emissions in electrolytic manganese production process,its emissions,low utilization rate,long-term storage of pollution of land,water and air and other natural resources.The main chemical composition of the electrolytic manganese slag is CaSO₄·2H₂O and SiO₂,and it is rich in sulfate minerals,such as calcium sulfate,which can be used as sulfate activator to improve the activity of the converter slag cementitious material.Therefore,the converter steel slag and the electrolytic manganese slag can be used to prepare the high activity cementitious material.This paper studied the effect of excitation effect conditions of heat treatment process of electrolytic manganese slag on sulfate,then to converter slag and process conditions in the best heat treated electrolytic manganese slag as the main raw material,adding auxiliary activators such as Ca?OH?₂,CaSO₄·2H₂O and clinker,the massive explorations in the early experimental foundation on the preparation of composite cementitious material by orthogonal experiment,analysis of electrolytic manganese slag dosage,Ca?OH?₂ influencing factors of dosage,CaSO₄ dosage of2H₂O and clinker admixture on the mechanical properties of composite cementitious materials,the optimum mix ratio of composite cementitious materials.The experimental results show that the electrolytic manganese slag heat treatment:the best condition of heat treatment process of electrolytic manganese slag is at 350?for 1h,under this condition,the soluble sulfate content in electrolytic manganese slag is higher,the activity of electrolytic manganese slag of converter slag better results.The results of orthogonal test showed that the optimal composite cementitious material with the ratio:the benchmark cement content:electrolytic manganese slag?at 350?for 1h?dosage:converter steel slag:Ca?OH?₂ volume:CaSO₄·2H₂O content:clinker admixture=315:25:110:6:4:12.The results of testing the mechanical properties of composite cementitious materials showed that:compared with the activity index of converter slag,the optimum proportion of 7d activity index of composite cementitious material was 88.2%,increased by 15.1%;the optimum proportion of 28d activity index of composite cementitious material was 89.5%,increased by 12.9%.By modern testing means of XRD and SEM to analysis the control ratio of mineral composition and microstructure of different age hydration products of compound cementitious materials with the experimental group,the experimental group and the optimal excitation mechanism of the composite cementitious material activity.Compared with the control group,the optimum proportion of hydration products of 7d composite cementitious material of the existence of a large number of C-S-H and CH,but also contains a certain amount of AFt and AFm;the existence of a large number of C-S-H and CH 28d in the hydration products,at the same time there is a certain amount of AFm,there is almost no AFt,and the microstructure is dense,the show that the hydration reaction of the early generation of AFt has been basically all into AFm,the hydration reaction of 28d is sufficient.