Novel development of affordable composite eco-cool roof tiles from waste materials: an experimental study

Roofing materials are essential to building energy efficiency, particularly in hot climatic regions; however, cement-based conventional tiles have environmental drawbacks, and advanced cool roof technologies remain economically impractical for widespread use in developing areas. Limited research has explored facilitating affordable and efficient thermal solutions, especially utilizing construction, demolition and industrial waste. The study aims to develop novel Composite Eco-Cool Roof Tiles (CECTs) using a synergistic mix design that integrates cement with recycled waste materials including Terrazzo Waste Powder (TWP), Glass Waste (GW), Marble Chip Waste (MCW), and Silica Fume (SF) as Eco-Aggregates (EA). A structured four-phase framework was utilized in the experimental method to develop and evaluate eighteen CECT formulations. Phase 1 included raw material selection, design optimization for the synergistic mix, and tile specimen manufacture. Experiments in Phase 2 included thermal characterization (thermal conductivity, solar reflectance, and specific heat capacity), physico-mechanical evaluation (compressive strength and water absorption), and SEM analysis of microstructure. Phase 3 assessed overall performance across all criteria, whereas Phase 4 summarized key findings from the experimental program. The M10-(GW) optimal mix design achieved a thermal conductivity of 0.209 W/m·K, outperforming conventional tiles by 63.13%. It also demonstrated a specific heat of 0.966 J/kg·K, reflectance of 0.69, the lowest water absorption rate at 2.809%, and a high compressive strength of 43.6 MPa, suggesting a potential cooling energy reduction of 33–54%. CECT enhances thermal performance and mechanical strength while meeting ASTM and ECP 204 standards, promoting sustainability and the circular economy through effective waste material use.