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The effects of two kinds of graphite powders with different particle sizes and their contents on the fluidity, setting time, mechanical strength and thermal conductivity of phosphogypsum based self-leveling mortar were studied. The results show that the fluidity of mortar decreases, the setting time shortens, the strength decreases, and the thermal conductivity increases linearly with the increase of the mass fraction of cementitious material replaced by graphite powder. At the same dosage, the fluidity and mechanical strength loss of mortar mixed with 1200 mesh graphite powder are smaller, while the setting time of mortar with 325 mesh graphite powder is shortened more slowly and the thermal conductivity rises faster; The hydrophobic and agglomeration effects of graphite powder will reduce the fluidity of mortar, while its surface nucleation and micro aggregate effect will shorten the setting time of mortar and can make up part of the strength loss. Besides, the addition of graphite powder with high thermal conductivity will reduce the internal thermal resistance, form thermal conduction channels, and improve the thermal conductivity of self-leveling mortar. The optimized phosphogypsum based self-leveling mortar mixed with 6% 1200 mesh graphite powder meets the requirements of the standard JC/T1023-2021 "Gypsum based self-leveling motor", and its thermal conductivity is increased by 37.1%. [ABSTRACT FROM AUTHOR]

The glass-ceramics were prepared by using MgO to replace part of CaO in the R2O-SiO2-CaO-Al2O3-F (RSCAF) system, and the effect of MgO content on the crystallization behavior of the glass-ceramics was investigated systematically. The results show that the main crystalline phase of the glass-ceramics is canasite after heat treatment when the RSCAF system without MgO (CaO content is 16.5%, mass fraction, the same below). Then, the crystalline phase in the microscopic morphology of the glass-ceramics presents a indented appearance and the density of the glass-ceramics is less than that of the basic glass. As the content of MgO in the RSCAF system is in the range of 0% to 3%, the crystallinity of the glass-ceramics reduces with the decrease of CaO content. Along with the further increase of MgO content and the decrease of CaO content in the system, the main crystalline phase of the glass-ceramics transforms gradually from canasite into diopside, and the crystalline diopside phase with columnar and flake-shaped appearance increases in the microscopic morphology and the density of glass-ceramics increases gradually. When the content of MgO in the system increases to 4% (CaO content decreases to 12.5%), the main crystalline phase of the glass-ceramics completely changes to diopside, and the crystallinity of diopside increases compared with that of the main crystalline canasite phase glass-ceramics, and the density of the glass-ceramics is higher than that of the basic glass. [ABSTRACT FROM AUTHOR]