EVALUATION OF COMPRESSIVE STRENGTH, WATER ABSORPTION, AND THEIR INTERRELATIONSHIP IN GLASS WASTE POWDER-MODIFIED CONCRETE EXPOSED TO AN ACIDIC ENVIRONMENT

Abstract

Acidic deterioration in sewage and industrial infrastructure poses a critical durability challenge for conventional concrete. Incorporating ultra-fine Glass Waste Powder (GWP) as a pozzolanic supplementary cementitious material consumes vulnerable calcium hydroxide and refines the pore structure to restrict fluid ingress. This study evaluated the compressive strength and water absorption of concrete with GWP replacing Portland limestone cement (Grade 42.5N) at 0% (control), 5%, 10%, and 20% by weight, with a water/cement ratio of 0.50. Compressive strength and water absorption tests were in accordance with BS EN 12390-3 and BS 1881-122:2011, respectively, and were correlated using linear regression. Standard 100 mm cubical specimens were cured in water for 28 days, then immersed in 3% sulfuric acid (H₂SO₄, ~0.55 M, pH of 0.85 ± 0.15) for 3, 7, 21, and 28 days. After 28 days of acid exposure, control concrete lost 17.4%  compressive strength (24.2 to 20.0 MPa). The 5% GWP mix achieved the highest 28-day residual strength (22.1 MPa, 10.5% above control; 11.9% loss), while 20% GWP recorded the lowest fractional strength loss (9.7%). The 10% GWP mix minimized water absorption at all ages, reaching 4.55% at 28 days (35.9% lower than the control's 7.10%). Regression analysis showed a good negative linear correlation between compressive strength (S) and water absorption (W) (S = 28.01 - 1.10W, R² = 0.862). Pozzolanic reaction of fine glass particles generates secondary calcium-silicate-hydrate (C-S-H) gel, restricting aggressive ion ingress. Hence, GWP is a highly effective, sustainable alternative binder for enhancing concrete durability in aggressive acidic environments.