The effect of Mount Sinabung volcanic ash and the addition of silica fume as a partial substitution of cement weight on the compressive strength of concrete

Abstract

The use of concrete continues to grow due to its superior performance compared to alternative construction materials; however, rising cement costs significantly increase production expenses. This study investigates the use of Mount Sinabung volcanic ash and silica fume as partial cement replacements to improve cost efficiency, reduce cement consumption, and enhance sustainability and mechanical properties. This approach not only contributes to the development of eco-friendly concrete technology but also provides a potential solution for managing volcanic ash waste from volcanic eruptions in Indonesia. Previous studies have primarily evaluated volcanic ash and silica fume separately, whereas their combined effects in concrete mixtures remain insufficiently explored, particularly in terms of compressive strength and mixture performance. Therefore, this study aims to evaluate the influence of incorporating both materials simultaneously. A total of 18 cylindrical concrete specimens (150 mm in diameter and 300 mm in height) were prepared with a target compressive strength of 25 MPa, consisting of six mix variations with three specimens each. The results showed that normal concrete achieved an average compressive strength of 25.16 MPa, while mixtures containing volcanic ash alone exhibited lower strengths, although an increasing trend was observed with higher replacement levels. However, the combination of volcanic ash and silica fume demonstrated improved performance compared to volcanic ash-only mixtures. These findings indicate that silica fume enhances the pozzolanic reaction and improves the concrete microstructure, suggesting that the combined use of these materials offers a promising approach for producing sustainable and cost-effective concrete with acceptable mechanical performance in practical construction applications.