Effects of Aggregate Packing on Concrete Strength and Consistency

Designing concrete based on aggregate packing and optimized gradations can result in 25 % less cement content to reach a targeted compressive strength and less water-reducing admixture to obtain a required consistency. In this research, two studies were conducted: (1) an experimental analysis to determine the effects of aggregate packing on concrete strength and consistency; and (2) an investigation of the relationship between the traditional dry-rodded and the vibrated aggregate packing. Excellent correlation was found between 240 packing results, which can be applied to the modified mixture design method presented. Also, 40 slump and 120 compressive strength standard tests were performed to evaluate the effects of reducing cement content by 7.5, 15, 20, and 25 % to slump and compressive strength of concrete mixtures. The compressive strength of the optimized mixture demonstrated less susceptibility to variations due to cement content reductions when compared to nonoptimized mixtures. The Modified Coarse Factor Chart can be used to design an optimized concrete mixture efficiently in conjunction with aggregate gradation and packing, cement content, and concrete consistency.