Investigation of the Effect of Micro-Silica Replacement on the Mechanical Behavior of Slag-Based Geopolymer Concrete

Document Type : Research Paper

Authors

1 Professor, Department of Civil Engineering, Faculty of Engineering, University of Guilan, Rasht, Iran

2 PhD Student

10.22124/jcr.2025.29870.1693

Abstract

This study examines the effect of replacing slag with micro-silica on the mechanical behavior of slag-based geopolymer concrete. Four different mix designs were prepared with varying percentages of micro-silica replacement (0%, 5%, 10%, and 15%), and the compressive and tensile strengths were evaluated at different curing ages (7, 28, 56, and 90 days). The results showed that at 7 days, the incorporation of micro-silica led to a reduction in both compressive and tensile strengths. However, this reduction was compensated for at later ages, with the mix containing 10% micro-silica showing the greatest improvement in mechanical properties. At 28 days, the 10% micro-silica mix exhibited the highest increase in compressive and tensile strengths, and continued to demonstrate significant improvements at 56 and 90 days. The findings suggest that the optimal amount of micro-silica to replace slag in geopolymer concrete is 10%, which notably enhances the material’s mechanical performance over time. This study highlights the potential of micro-silica as an effective additive for improving the long-term mechanical properties of slag-based geopolymer concretes.

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