Heat-resistant cementitious composites based on binders derived from cement and metallurgical waste.

One of the main aspects of consideration in building safety and durability in fire and extreme conditions is the high-temperature performance of cementitious composites. The paper is concerned with the construction of alumina-rich binder systems using industrial by-products like bauxite residue and perlite to enhance the thermal stability as well as sustainability. The primary goal was to develop and test composites that could sustain mechanical integrity at exposure levels up to 1380o C. The experimental program included the preparation of three mixtures that were mixed using various ratios and proportions of reactive alumina and bauxite residue with water. The size distribution of all the granular parts was also analyzed in order to determine packing density. Tests were done on compressive strength, porosity, and thermal resistance, and SEM analysis were done to determine any changes in the microstructure post-heating. This hybrid method allowed for correlating the mixture design, physical properties, and performance at high temperatures. The findings showed that optimized formulation (F3) was able to reach compressive strength over 52 MPa at ambient temperature, and it could withstand a compressive strength higher than 70% even when subjected to 1200o C. Reduced water to binder ratios and a greater proportion of fine reactive alumina were key factors in enhancing the density and mechanical strength of the composites, while bauxite residue promoted the formation of stable crystalline phases during heating. SEM analysis confirmed the densification of the matrix, and the chemical composition suggests the development of thermally stable phases upon heating. These results provide a positive relationship between mix design parameters, microstructural evolution, and macroscopic performance. Finally, the research offers evidence that cementitious composites with a controlled mixture design that are composed of alumina can be used to achieve a high compressive strength with outstanding thermal stability. This emphasizes their applicability in construction and infrastructure vulnerable to intense thermal loads and hostile to fire-resistant materials, as well as encourages the valorization of industrial waste materials.