Effects of finer gradation, temperature, warm mix additives, and compaction methods on density and performance of asphalt mixtures

The pavement service life can be extended by producing asphalt mixes that are easier to compact and are more likely to result in higher in-place density during construction. Some potential strategies to improve compactibility and increase density include finer gradation, warm-mix asphalt (WMA) additives, increasing binder content, and increasing the asphalt mixing and compaction temperatures. In this study, the cracking and rutting performance of a more economical mix design method with finer gradation was quantified and compared with the standard mixes. The effect of using WMA chemical additives on the compactibility and performance of HMA mixes was also determined. Besides, the impact of temperature and high binder content were investigated on both gyratory compacted, and roller compacted samples in the laboratory. The results indicated that WMA mixes provided significantly higher (1.5 to 2 times higher than the HMA levels in some cases) cracking resistance than the corresponding HMA mixes.