Preparation and properties of novel multi-component refractory cementitious materials

Abstract

In order to improve the high-temperature resistance of cementitious materials and further improve their high-temperature resistance theory, this thesis studies a new type of refractory cementitious material. Through systematic research, the material composition of multi-component cementitious materials was optimized. The changes of basic properties such as mass loss, water absorption and strength of composites after high-temperature treatment at 300 °C, 550 °C, 850 °C, 1200 °C and 1300 °C were studied, and the microscopic characteristics such as phase composition, apparent morphology and thermal stability of the composites were analyzed by XRD, SEM and TG-DSC test methods. The results showed that the synergistic effect of iron tailings powder/fly ash/metakaolin (ITP/FA/MK) could significantly improve the residual strength of the material after high-temperature treatment at 1200–1300 °C. On the basis of FA, 11% MK was added to reduce the quality loss after high-temperature treatment. Based on the M0 test block, 10.7%∼32.2% ITP can significantly reduce the quality loss of materials after high-temperature treatment. The XRD results showed that the material phase contained sanidine and mullite before the high-temperature treatment at 850 °C. After the high-temperature treatment at 1200–1300 °C, there was anorthite and gehlenite in the material phase, which was the key to maintaining the strength of the material. The SEM results showed that many hydration products were attached to the surface of FA beads in the sample slurry mixed with MK, FA and ITP at room temperature, making the combination of FA beads and hydration products closer. After the material is treated at a high temperature, the “skeleton” of the material becomes denser. The research on this topic plays a guiding role in the study of the performance of cementitious materials under higher temperature treatment. It reveals the influence and mechanism of admixtures such as ITP, FA and MK on cementitious materials' high-temperature mechanical properties and microstructure. Finally, the M0 test block was not damaged, the strength did not decrease, the mass loss was not significant after high-temperature treatment, and the mass loss rate after high-temperature treatment at 1300 °C was only 10.5%, which met the needs of new refractory cementitious materials.