Multifunctional Aggregate-Gypsum Composites Combining Mechanical, Thermal, and Pollutant-Removal Functions: A Critical Overview

This study presents a data-driven evaluation of recycled-aggregate gypsum composites by examining the relationships between dry density, mechanical performance, thermal conductivity, and formaldehyde adsorption. Analysis of published experimental data shows that dry density is the primary parameter governing overall material performance. Compressive strength increases with density, whereas lower-density composites provide superior thermal insulation. An optimal multifunctional performance range was identified at 900–1100 kg/m3, where a favorable balance between strength and insulation efficiency is achieved. Aggregate type also influences performance: polymer-based aggregates produce the greatest density reduction, biomass-derived aggregates offer a balanced combination of properties, and mineral-based aggregates generally maintain higher stiffness. Assessment of environmental functionality indicates that conventional gypsum composites possess limited formaldehyde and CO2 adsorption capacity, although biochar and other bio-based modifications can significantly enhance adsorption performance. These findings provide a practical framework for designing sustainable gypsum composites with balanced structural, thermal, and indoor air quality benefits.