Associate professor of civil engineering, Lakehead University, Thunder Bay, Ontario
Existing aggregate blending methods can be used to provide the optimum proportions based on either gradation or cost requirements. The purpose of this paper is to present an analytical method that allows a trade-off between gradation and cost requirements in determining the optimum proportions. Only three aggregates are considered, but the method can be extended to any number of aggregates. The method provides the entire feasible region of proportions that satisfies the gradation specification limits along with the mean deviation and cost of every point in that region. The mean deviation can be based on mid-point specifications or the maximum density gradation curve. The optimum proportions for the minimum mean deviation, minimum cost, or a trade-off between the two are determined. The method was applied to two examples of aggregate blending. The first example illustrates the trade-off analysis of gradation and cost requirements, and the second example illustrates a special advantage of the method. In addition to considering both gradation and cost requirements, the method has other advantages. Unlike existing methods, this method automatically eliminates negative solutions and can handle any type of the cost function of aggregates.
Paper ID: CCA10041J