STUDYON THE EFFECT OF FINE TO COARSE AGGREGATE RATIO ON THE CONCRETEPROPERTIES

Abstract

Concrete is the most commonly used construction material in the world. It is basically composed of two components: paste and aggregate. Coarse and fine aggregates contain almost up to 75% of the total concrete volume therefore, balancing the usage of fine and coarse aggregate plays a vital role in determining the performance and strength of the concrete. However, there is limited literature available on the use of fine to coarse aggregate ratios for a mixed design for concrete. Consequently, further research is needed to ascertain the impact of a higher fine-to-coarse aggregate ratio on concrete.This research work was conducted to arrive at an optimum fine-to-coarse aggregate ratio in terms of the properties of both fresh and hardened concrete. The experimental research design approach was carefully designed to meet the stated objectives once the research problem was identified and the research objectives were specified. In order to investigate the performance of concrete, this study was used varying mix proportions with fine-to-coarse aggregate ratios increasing and decreasing, respectively, at percentages of 10, 20, 30, and 40% and the resultant concrete strength after 7, 14 and 28 days recorded. This study investigates the effect of varying fine-to-coarse (F/C) aggregate ratios on the mechanical and fresh properties of concrete. Seven different concrete mixes were prepared with F/C aggregate ratios of 0.306, 0.384, 0.475, 0.583, 0.872, 1.07, and 1.324, based on a reference mix with an F/C ratio of 0.713. Key findings indicate that increasing the sand content (i.e., higher F/C ratios) requires more cement paste for workability, leading to challenges in surface finishing. Concrete with higher F/C ratios exhibited lower workability and decreased fresh density, which ranged from 2083 to 2495 kg/m³. Specifically, a 30% increase in the F/C ratio resulted in a 9.45% reduction in fresh density compared to the control mix. The study also found that the compressive strength remained relatively constant for F/C ratios between 0.384 and 0.872, but a sharp decline of 40.37% occurred when the ratio reached 1.324. Similarly, the splitting tensile strength was significantly affected when the F/C ratio deviated from the reference mix. The results suggest that minor adjustments in the F/C ratio (between 0.384 and 0.872) do not significantly impact the concrete's design strength or workability. Based on these findings, it is recommended that concrete mix designers carefully consider the F/C aggregate ratio to optimize both the fresh and mechanical properties of concrete. Further research is needed to explore the long-term effects of aggregate ratios on durability, as well as the influence of admixtures and different water-to cement ratios.