Synergistic mechanical and environmental performance of cow bone ash-brass dross hybrid composites for ceiling applications

This study investigates the synthesis of eco‑composite ceiling boards via valorization of brass dross and cow bone ash (CBA) in an epoxy matrix for enhanced thermal, mechanical, and fire-resistant behavior. Brass dross with 45.8 wt% Cu and 25.3 wt% Zn, and CBA with 26.0 wt% CaO, were wet‑ground to 300 µm and incorporated in the range 0–10 wt% into open-mould-fabricated panels (300 × 300 × 12 mm). Microstructural analysis by SEM/EDS proved porous dispersion pf CBA at 10 % wt% CBA, with agglomeration over higher loadings. Mechanical properties proved optimal flexural strength (2.415 MPa) and hardness (88 N/mm²) at 3.33 wt% and 6.67 wt% CBA, respectively, followed by small decreases at 10 wt% by virtue of particle clustering, partially compensated by metal reinforcement. Modulus of rupture and elasticity were greatest at intermediate CBA contents, implying an optimum stiffness-toughness trade-off. Water absorption displayed a non‑linear pattern with a peak at 0.23 % at 3.33 wt% CBA, afterward decreasing as improving brass dross ensured matrix integrity. Thermal conductivity enhanced up to 6.67 wt% CBA (0.138 W/mK) and reduced at 10 wt%, but specific heat capacity improved by 25.7 % at 6.67 wt%. These observations indicate that industrial and agricultural wastes hybridization has the potential to deliver ceiling panels of competitive performance and sustainability quality.