Aggregates breakage introduction to optimize gradation of multi-supporting skeleton asphalt mixtures

摘要

This research provides a method for introducing the broken rate of the coarse aggregates to optimize gradation of multi-supporting skeleton asphalt mixtures (MSSAM). The MSSAM was designed and then verified by comparing the measured volume parameters with designed criterion. Single Marshall tests were performed on single and multiple sized aggregates to find the boundary of coarse and fine aggregates. The tamping method replaced the Marshall compaction to measure accumulated density of the coarse aggregates. The broken rate of the coarse aggregates was introduced to optimize gradation of MSSAM. The wheel-tracking and low-temperature bending tests were finally performed to evaluate the pavement performances of the modified MSSAM. The results indicated that the gradation degeneration of MSSAM introduced by the crushed coarse aggregates resulted in the volume parameters to deviate from the designed criterion. The grain size of 4.75 was identified as the boundary of coarse and fine aggregates. Introduction of the broken rate of the coarse aggregates neutralized the gradation degeneration in the Marshall compaction, and brought the measured volume parameters nearer to the designed criterion. The modified MSSAM had a high dynamic stability and met requirements of low-temperature performance at minus 9 degrees C, was a good choice for the southeast China with heavy traffic. (C) 2018 Elsevier Ltd. All rights reserved.