Characterization and Mechanical Performance of Geopolymer Concrete Incorporating Industrial Waste Materials

This study examines the effect of incorporating incinerated biomedical waste ash (IBWA) as a partial substitute for ground granulated blast furnace slag (GGBS) in geopolymer concrete. The replacement of GGBS with IBWA was carried out at levels of 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50% by weight of the binder. An alkaline activating solution comprising sodium hydroxide (NaOH) and sodium silicate (Na2SiO2) in a ratio of 1:2.5 was employed, with an alkaline-tobinder ratio of 0.61. The fresh properties of the concrete were evaluated using slump and compaction factor tests, while hardened properties were assessed through water absorption, compressive strength, splitting tensile strength, and flexural strength tests. The results showed an improvement in workability up to 20% IBWA replacement, followed by a decline at higher replacement levels. Maximum mechanical performance was achieved at 20% IBWA, with compressive strength, splitting tensile strength, and flexural strength values of 53.62 MPa, 4.81 MPa, and 6.74 MPa, respectively, at 28 days. Water absorption initially decreased and reached its lowest value of 2.46% at 20% IBWA before gradually increasing with further additions. These results demonstrate that IBWA can replace GGBS effectively up to 20% without adversely affecting structural performance, offering a viable and sustainable alternative material for geopolymer concrete production.