Development of eco-friendly gypsum composite using gypsum binder and gypsum waste aggregates

Abstract

The development of sustainable building materials is increasingly focused on integrating regenerative resources and secondary raw materials obtained through industrial symbiosis. In this context, gypsum composites represent a promising solution for reducing environmental impact in the construction sec-tor. The raw materials used for gypsum composites include not only building gypsum (BG) but also gypsum-based demolition waste (GDW). In this study, gypsum composites were produced using BG binder combined with varying proportions of fine recycled fillers derived from GDW. The primary aim was to evaluate whether incorporating GDW can reduce environ-mental impact while maintaining mechanical performance comparable to reference gypsum composites without recycled material. BG was substituted with 10, 20, 30, and 40 wt% GDW, and the gypsum-to-water (G/W) ratio varied from 0.5 to 0.7. For each composition, nine samples were tested. The structural and mechanical behavior of the composites was assessed using X-ray diffraction (XRD), scanning electron microscopy (SEM), compressive strength tests, hydration temperature measurements, and loss-on-ignition analysis. The results showed that the proportion of recycled fillers significantly influenced the key material properties. Notably, a slight improvement in compressive strength was observed in the eco-friendly composites: the reference sample achieved 13.85 MPa, whereas the composite containing 10 wt% GDW reached 15.95 MPa. However, higher GDW content led to a reduction in com-pressive strength. This increase can be attributed to the micro-filler and nucleation effects of GDW, which produced denser microstructure and improved bonding characteristics.