Study on carbon reduction of Ultra High-Performance Concrete using fly ash as an admixture instead of hydraulic cement

Abstract

This research investigates the properties of Ultra-High-Performance Concrete (UHPC), which exhibits superior strength and durability compared to conventional concrete. However, UHPC has higher costs and environmental impacts due to the significant use of cement and silica fume. Therefore, this study focuses on developing UHPC by reducing cement consumption through partial replacement with fly ash at 0%, 10%, 20%, 30%, and 40%. Additionally, silica fume and steel fibers were incorporated to enhance strength. The compressive strength test results at 28 days revealed an average compressive strength of 1,631 kg/cm². The UHPC mix with 40% fly ash replacement achieved the highest compressive strength of 1,480 kg/cm², which is approximately 20.41% lower than that of the control mix containing only cement. However, the strength remains within acceptable standards, making it suitable for civil engineering applications. Furthermore, replacing cement with fly ash in UHPC significantly reduces carbon dioxide (CO₂) emissions from the construction industry while minimizing industrial waste from power generation. Additionally, UHPC has a service life exceeding 100 years, reducing the need for repairs and new materials, thereby promoting sustainable construction practices.