Mechanical Properties and Environmental Impact of a Sustainable Ultra-High-Performance Concrete using High-Content Fly Ash

^1,3 Structural Eng. Res. Unit, Fac. of Eng., Mahasarakham Univ., Maha Sarakham, 44150, Thailand
² Water Resources and Envi. Eng. Res. Unit & Circular Resources and Envi. Protection Tech. Research Unit, Fac. of Eng., Mahasarakham Univ., Maha Sarakham, 44150, Thailand

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

This research aims to develop a sustainable Ultra-High-Performance Concrete (UHPC) by using high-volume Class F fly ash to replace cement at ratios of 20%, 40%, and 60% by weight to reduce cement usage primary source of CO2 emission, combined with mixed-sized steel fibers at 2% by volume. All mixtures incorporated 8-mm limestone aggregates and were cured under standard water curing conditions. The investigation of mechanical properties included compressive strength, splitting tensile strength and flexural strength. The evaluation encompassed carbon emissions and the cost evaluation of each mixture in comparison to a reference UHPC. Experimental results revealed that at 28 days, mixtures containing fly ash at 60% ratio exhibited the lowest compressive strength at 117.0 MPa but could reduce carbon dioxide emissions by up to 38% when compared to the reference mixture Regarding splitting tensile strength, the mixture incorporating 20% fly ash achieved the maximum value of 22.1 MPa, whereas the flexural strength of the mixture using 40% fly ash provided the highest value of 22.7 MPa, which exceeded the reference mixture. The findings demonstrate that utilizing an of fly ash combined with mixed-sized steel fibers facilitates the production of a sustainable UHPC with satisfactory mechanical properties and reduces costs.