Feasible use of titanium slag in improving properties of low carbon fire-resistive cementitious composites at elevated temperatures

The dumping of titanium slag (TS) and fly ash (FA) could lead to the occupancy of abundant land resources and the pollution of air, soil and underground water. The meso-regulatory function of the lightweight and thermally stable porous TS makes it a feasible material as the fire-resistive cementitious composites (FRCCs). This paper proposed a novel low-carbon FRCC with favorable high-temperature resistance by using TS and FA. Then, the mechanical properties and mechanism improving the heat resistance were systematically studied. The results revealed that the addition of TS with proper quantity decreases the mass loss by 19.6% and degradation degree of mechanical strength by 31.8% after 800 ℃ heating. The thermally stable perovskite and akermanite phases in TS are conducive to improving the stability of mineral phases during high-temperature heating. Meanwhile, the porous structure of TS enhances the thermal insulation of FRCC, which postponed the mineral phase decomposition. In addition, the secondary hydration effect of FA consumes a large amount of Ca(OH)2, which effectively weakens the deterioration caused by the decomposition of Ca(OH)2 after 600 ℃ heating. Based on the CT results, the variations of internal pore structure including pore distribution, porosity, and fractal dimensions, were systematically analyzed. It is found that the TS particles can effectively optimize the internal pore distribution and limit the generation and deterioration of macro-pores. Moreover, the thermal damage model of the prepared FRCC was established by combining the pore structure deterioration degree and residual mechanical strength. Finally, compared with traditional fire-resistive fillers, the low carbon emission of the prepared FRCC was verified.