Implementation of concrete aggregate optimization

• A method to determine an optimized combined gradation is described.
• An ideal aggregate gradation is developed and modeled using two cubic polynomials.
• The ideal gradation plots as a “haystack” on the percent retained chart.
• The optimization process is iterative and depends on the available aggregates.

The implementation of a step-by-step concrete mixture design procedure to determine an optimized aggregate gradation is described. The procedure uses both the modified coarseness factor and percent retained charts to establish an optimal blend of user-selected aggregates, criteria that are usually not implemented simultaneously. The design process is iterative and depends on the gradations of available aggregates, the cementitious material content of the concrete mixture, and the maximum aggregate size. The procedure can be implemented using a spreadsheet and, unlike traditional approaches, is capable of blending aggregates with significantly different specific gravities.