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In this paper, modified cementitious powders with different doping amounts of calcium carbide slag (0,0.5 wt%,1.0 wt% and 1.5 wt%) were prepared with 32.5 grade ordinary portland cement, II grade fly ash and mirabilite as raw materials and industrial waste calcium carbide slag as additive materials. The effects of calcium carbide slag doping on the crystal structure, micro morphology, mechanical properties, setting time and combined water content of modified cementitious powder were analyzed.The results show that the doping of carbide slag doesn’t produce new products, but accelerates the consumption of C2S and C3S and improves the rate of hydration reaction.When the doping amount of carbide slag is 1.0 wt%, the hydration products are most closely combined.With the increase of calcium carbide slag doping, the setting time of the modified cementitious powder gradually decreases, and the compressive strength and chemical binding water content at 28 d first increase and then decrease.When the doping amount of carbide slag is 1.0 wt%, the compressive strength and chemical binding water content at 28 d reach the maximum, which are 2.98 MPa and 6.8% respectively.This is because the addition of appropriate amount of calcium carbide slag accelerates the hydration reaction of cementitious powder, increases its structural compactness, and improves the mechanical properties of cementitious powder.It can be seen that the optimum doping amount of carbide slag is 1.0 wt%. [ABSTRACT FROM AUTHOR]

A series of SiC porous ceramic powders with different sintering temperature (1 600,1 630,1 660 and 1 690 ℃) are prepared by reactive sintering process. The phase structure, microstructure, porosity and mechanical properties of SiC porous ceramics are characterized by XRD, SEM, porosity test, compressive strength test and oil-water separation test. The results show that the characteristic diffraction peak intensity of SiO2 increases with the increase of sintering temperature, and the characteristic diffraction peak intensity of SiO2 is the highest at 1 690 ℃. With the increase of temperature, the porosity of SiC porous ceramics first decreases and then increases, and the lowest porosity is 32.1% at 1 660 ℃. SEM analysis shows that the SiC porous ceramics sintered at 1 600 and 1 630 ℃ contain more small particles, and the particles are dispersed. With the increase of sintering temperature, the small particles decrease gradually, and the SiC porous ceramics shrink and grow up gradually. The analysis of mechanical properties shows that the compressive strength of porous SiC ceramics increases firstly and then decreases slightly with the increase of sintering temperature, and the maximum compressive strength is 25.6 MPa at 1 660 ℃. The oil-water separation test shows that with the increase of sintering temperature, the membrane flux of SiC ceramics decreases first and then increases slightly, and the rejection rate increases first and then decreases slightly. When the sintering temperature is 1 660 ℃, the membrane flux is 553.8 L/(m²·h) and the rejection is 91.5%. [ABSTRACT FROM AUTHOR]