ENHANCING GEOPOLYMER CONCRETE: MECHANICAL BEHAVIOR ANALYSIS WITH NANO-SILICA

Abstract

The widespread use of Portland cement concrete contributes significantly to carbon emissions, creating a need for sustainable alternatives such as geopolymer concrete (GPC). Despite its potential, GPC often shows inconsistent mechanical properties, particularly in early-age strength, limiting its broader application. Nano-silica has proven effective in cementitious composites, yet its influence on GPC, especially in terms of dosage optimization and microstructural behavior, remains underexplored.

This study examines the effect of nano-silica (0–4% by fly ash weight) on the mechanical and microstructural properties of GPC. Mechanical tests (compressive, tensile, and flexural strength) and microstructural analyses (SEM, XRD) were conducted, supported by statistical evaluation using ANOVA, Tukey HSD, and regression. The results indicate that 3% nano-silica achieved the highest compressive strength (39.66 ± 0.91 MPa), a 24.2% increase over the control, while tensile and flexural strengths improved by 32.4% and 24.2%, respectively. Microstructural analysis revealed denser matrices with lower porosity (8.5% vs. 12.5% in control). Workability decreased with increasing dosage, with the optimum balance observed at 2–3%, beyond which agglomeration occurred.

Overall, nano-silica enhances the mechanical performance and microstructure of GPC, offering a cost-effective and sustainable pathway for low-carbon infrastructure.