Enhancing physical, mechanical, and durability properties of slag-based geopolymers through ceramic waste incorporation: A comprehensive optimization study

Abstract

Background: The demand for sustainable construction materials has driven research into geopolymer mortars (GPs) as an alternative to cement-based materials. This study explores the use of ceramic waste powder (CWP) as a partial replacement for ground blast furnace slag (GBFS) in GPs, optimizing mix design to enhance workability, mechanical performance, and durability. The influence of CWP content and activator-to-precursor (Ac/Pr) ratio was systematically evaluated. Methods: Nine GP mixtures were formulated using a central composite design (CCD), varying CWP content (0–25 %) and Ac/Pr ratio (0.7–0.75). Workability was assessed via slump test, compressive strength at 7 and 28 days, and water absorption to evaluate porosity. Sulfuric acid resistance was tested after 60-day immersion in a 3.5 % acid solution. Phase composition was analyzed using FTIR and SEM/EDX, and desirability optimization identified the optimal mix. Significant Findings: Increasing CWP content improved workability and long-term compressive strength, with the optimal mix (21.693 % CWP, Ac/Pr = 0.725) achieving 86.343 MPa at 28 days and 6.093 % water absorption. CWP enhanced acid resistance, reducing strength loss to 35.531 % due to a stable aluminosilicate network. FTIR confirmed degradation mechanisms, including decalcification and dealumination. The study highlights CWP's potential in GPs, balancing workability, strength, and durability. Its enhanced resistance to acidic environments makes it a promising material for sustainable construction, particularly in wastewater treatment infrastructures and industrial flooring exposed to harsh chemical conditions.