Laboratory investigation of compaction characteristics and performance of warm mix asphalt containing chemical additives

This paper focuses on the compaction characteristics and performance of warm mix asphalt containing chemical additive. Viscosity tests indicated the used chemical additive had a limited effect on viscosity reduction. Investigation into the ease of compaction showed that asphalt mixtures containing 2% chemical additive allowed compacting at lower temperatures and mixture compactability was less dependent on bitumen viscosity. It was demonstrated that the compactability of warm mix asphalt could be well ranked by using various indicators including the number of gyrations to achieve a design void content, the slope of accumulated compaction energy against the number of gyrations as well as compaction energy indices at various compaction phases. Data obtained from immersion wheel tracking tests indicated that warm mix asphalt containing chemical additive did not have a performance comparable to that of hot mix asphalt. Rutting and stripping were found to be the main causes resulting in poor performance.