Predictive modeling of glass powder and activator effects on slag-based geopolymers via central composite design

Abstract

This study investigates the effects of glass powder (GP) content and activator-to-precursor (Ac/Pr) ratio on the properties of slag-based geopolymer mortars using a central composite design approach. GP content ranging from 0% to 30% and Ac/Pr ratios between 0.65 and 0.75 were examined. Response surface methodology was utilized to construct predictive models for slump, 28-day compressive strength, and porosity. Scanning electron microscopy and energy dispersive X-ray spectroscopy were utilized to analyze the microstructure and chemical composition of the geopolymer matrices. Results indicate that both GP content and Ac/Pr ratio significantly influence mortar properties. Increasing GP content and Ac/Pr ratio generally improved workability, while optimal mechanical performance was achieved at moderate levels of both factors. The optimal formulation, determined through desirability analysis, consisted of 18.2% GP content and 0.72 Ac/Pr ratio, yielding predicted outcomes of 16.53 cm slump, 46.64 MPa compressive strength, and 15.85% porosity. This study demonstrates the potential of incorporating waste glass in slag-based geopolymers and provides a framework for optimizing mix designs to achieve desired performance characteristics.