Given the amount of industrial waste produced and collected in the world today, a recycling and recovery process is needed. The study carried out on this subject focuses on the valorization of one of these industrial wastes, namely the fly ash produced by an ultra-supercritical coal power plant. This paper describes the use and recovery of fly ash as a high percentage reinforcement for the development of a new high-performance composite material for use in various fields. The raw material, fly ash, comes from the staged combustion of coal, which occurs in the furnace of an ultra-supercritical boiler of a coal-fired power plant. Mechanical compression, thermal conductivity, and erosion tests are used to study the mechanical, thermal, and erosion behavior of this new composite material. The mineralogical and textural analyses of samples were characterized using Scanning Electron Microscopy (SEM). SEM confirmed the formation of a new composite by a polymerization reaction. The results obtained are very remarkable, with a high Young’s modulus and a criterion of insulation, which approves the presence of a potential to be exploited in the different fields of materials. In conclusion, the composite material presented in this study has great potential for building material and could represent interesting candidates for the smart city.