Building on the work performed under NCHRP Projects 4-20 and 4-20A, this project proposed a plan for a laboratory study to further evaluate potential aggregate tests and to recommend a set of aggregate tests that relate to performance of portland cement concrete used in pavement construction that can thus be used as predictors of pavement performance.

The properties of coarse and fine aggregates used in portland cement concrete mixtures are very important to the performance of the highway pavements in which they are used, and proper aggregate selection is necessary for attaining desired performance. However, many of the currently used aggregate tests were developed empirically to characterize an aggregate without necessarily understanding the direct relationship to the performance of the final product. Because widespread use, familiarity, and a historical database have perpetuated the popularity of some tests, there is a need to evaluate existing aggregate tests, to identify new tests that relate to performance, and to develop better procedures for testing and for selection of aggregates used in portland cement concrete pavements. This project provided a step in the process for achieving this objective. Further research will be performed under NCHRP Project 4-20C.

Research included a review of relevant domestic and foreign literature, an evaluation of potential aggregate tests, and the development of a preliminary plan for a laboratory study.