Influence of the size of the coarse and fine aggregates on the compressive strength of concrete

Abstract

In this study, the influence of aggregate sizes on the compressive strength (CS) of concrete system has been assessed. Accordingly, the fine aggregates (FA) and coarse aggregates (CA) with fixed gradation sizes were considered and the prepared conventional concrete samples were assessed for their 7th and 28th day compressive strength. Thereby, three different types of FA were selected for FA particle size gradation. Striking variations in the CS values were noted for the concrete samples with a particular combination of FA and CA sizes, and for a fixed choice of the water-to-cement ratio. Further investigations for the CS modelling are conducted with the response surface methodology (RSM). Considering overall specific gravity (FA Sp.Gr.) as a parameter but not a factor, the experimental design considered the FA size (in µm) and CA size (in mm) as independent variables. The best-fit RSM model analysis inferred the quadratic model with good relevance (p < 0.001) for the prediction CS in the defined factor space and for three alternate FA types. The Pareto plots revealed that while the FA size was the influential factor for both responses for the case of the FA Sp.Gr. value of 2.59, while CA size was the highest contributor for the other two FA Sp.Gr. types. Thereby, the role of the type of FA and the aggregate sizes were assessed to be very important to achieve the high CS. The adopted methodology is generic for selecting the best-fit control sample for further research into advanced concrete composite materials.