Advocates of mixtures containing well graded combined aggregates argue that such mixtures have optimized packing and minimal voids and therefore minimize the cementitious paste required for a given workability. Opponents of well graded combined aggregates argue that they don’t necessarily lead to optimized performance, but might actually cost more. In an effort to resolve the controversy, a study was conducted at the National Ready Mixed Concrete Association Research Laboratory to determine whether well graded combined aggregates improve aggregate packing density and concrete performance. A summary of the research report is provided in this article.

Two sessions at the ACI 2008 Spring Convention will pay tribute to 13 landmark papers in concrete materials research and recognize the importance of materials innovations to the concrete community. The papers will be presented by noted experts that will describe each paper and its impact on the concrete community. A special publication associated with the sessions will be published, presenting each landmark paper in its original form along with a foreword from each presenter. "Proportioning Concrete Mixtures" by Duff A. Abrams is presented here with an abbreviated version of V.M. Malhotra’s foreword.