UTILIZATION OF SPENT ANTHRACITE FILTER MEDIA IN CEMENT MORTAR: STRENGTH AND DURABILITY ASSESSMENT

Abstract

This study investigates the utilization of spent anthracite filter media (SAFM) as a sustainable fine aggregate to partially replace natural sand in cement mortar. The experimental program evaluated the effects of SAFM replacement at 10%, 20%, and 30% by volume on the flowability, density, mechanical properties, and chemical durability under aggressive environments (NaCl, MgSO₄, and H₂SO₄). Mortar mixtures were prepared following ASTM standards with a constant water-to-cement ratio of 0.43. The results revealed that increasing SAFM content reduced the flow value from 115% (control) to 100% (30SAFM) and slightly decreased the density from 2136.0 to 2028.0 kg/m³ due to the lower specific gravity of SAFM. In contrast, the compressive and flexural strengths increased significantly by approximately 46% and 21%, respectively, at 30% replacement, indicating improved interfacial bonding and pore refinement. Durability tests demonstrated that SAFM enhanced resistance to chloride and sulfate attack, particularly under MgSO₄ exposure, where compressive strength after 90 days increased by 48% compared with the control. Although all specimens deteriorated under acidic conditions (H₂SO₄), SAFM delayed surface damage and mass loss. The findings confirm that SAFM can serve as an effective and eco-friendly alternative to natural sand, offering enhanced strength and durability while promoting the circular economy through waste reuse in sustainable construction materials.