Present Aggregate Gradation Control Practices and Alternative Test Methods

摘要

Under current highway construction practices, aggregate gradation must be controlled to help insure the production of good pavements. This study was undertaken to determine what control procedures are being used in the United States and how incorporation of alternative testing methods would effect the adequacy of the control and the amount of time devoted to doing it. A survey of control practices currently being used was conducted under Phase 1 of this study. The results of that survey are summarized herein. Alternatives to the standard test methods of gradation determination were evaluated in Phase 2. They were compared with the standard tests in terms of total testing time required and the accuracy of the gradation results. The sources of variation in test results and the relative importance of each were also investigated. Recommendations are given as to the frequencies of sampling and gradation testing based on the study findings.