Environmental-friendly high-strength concrete using hydraulic cement and river gravel residue

This research investigated the use of hydraulic cement (HC) and river gravel residue for the manufacture of high-strength concrete. HC with fly ash (FA) replacement at levels of 0%, 10%, 20%, and 30% was used as a binder, whilst a cost-effective mid-range water-reducing admixture (MRWR) was used to improve workability and enhance compressive strength of the mix. The river gravel residue from the construction sand production process was used as coarse aggregate. The concrete mix design followed ACI 211.4R-93, targeting a compressive strength of 60 MPa at 28 days. Effects of FA content and MRWR content on workability, compressive strength, and temperature variations during hydration were investigated in this research. The optimum FA replacement for the highest compressive strength was achieved at 20% and the MRWR was at 1.5%. The river gravel residue was proven to be an effective aggregate, improving workability and contributing to steady strength development. The novelty of this study lies in the use of river gravel, a locally available aggregate, in combination with HC containing pozzolanic constituents. With the addition of an appropriate level of FA and a cost-effective MRWR, high-strength concrete can be produced without relying on expensive high-range water-reducing admixture, providing a sustainable and practical solution for engineering applications.