Mix design optimization of high-performance concrete using local materials

Abstract

In this paper, twelve different concrete mixes made from local materials were studied with a view to determining which of the mix designs will produce high-performance concrete. Varied water-cement ratios (w/c) of 0.3, 0.35, and 0.4 were studied with different combinations of particle sizes of coarse aggregates. Twelve concrete mixes were then produced, cast, and cured for 7, 14, 21, 28, 45, and 90 days. Superplasticizer was used to facilitate the workability of the concrete mixes. A slump test was first conducted on the fresh concrete to determine its workability, while compressive, flexural, and tensile strength were determined at the end of each curing age in accordance with relevant standards. The results shows that slump value increased with an increase in w/c ratio, while the concrete with 100% 10 mm particle size coarse aggregate had a minimum slump of 24, 37, and 50 mm at w/c of 0.3, 0.35 and 0.4 respectively, but higher slump values of 70, 76 and 83 mm were obtained with concrete containing larger particle sizes combination i.e. 25% of each of 10, 12, 15 and 19 mm sizes. But strengths reduced with an increase in w/c and aggregate particle sizes. Concrete produced with w/c of 0.3 and 10 mm coarse aggregates had a strength of 52.22N/mm2 at 28 days, which was about 126% of other strengths obtained from other mixes. Statistical models were then proposed to predict the strength of the best-performed concrete mix. The study concluded that it was possible to produce high-performance concrete using local materials, if the mix is properly optimized.