Effects of Compaction Temperature on Volumetric Properties of Rubberized Mixes Containing Warm-Mix Additives

Abstract

The warm-mix asphalt (WMA) refers to technologies that allow a significant reduction of mixing and compaction temperatures of asphalt mixes through lowering the viscosity of asphalt binders. Several studies have been carried out evaluating the properties of WMA, and it is found that warm mix additives work in different ways either in reducing the viscosity of the binder or allowing better workability of the mix at lower temperatures. In terms of rubberized asphalt mixtures, they are generally produced and compacted at higher temperatures than conventional mixtures, based on the field experience. If the technologies of warm-mix asphalt are incorporated, it is expected to reduce the mixing and compaction temperatures of rubberized asphalt mixtures to those of conventional mixtures. This study was initiated to investigate the effects of compaction temperature on rubberized mixes containing the warm mix additives. For this, four Superpave mix designs for two asphalt binders and two aggregate sources were conducted to determine optimum asphalt contents. Warm rubberized mixes were produced using two of the available processes. A total of 192 specimens (4 mix types: control mix, rubberized mix, warm rubberized mix 1, and warm rubberized mix $2\times 2$ aggregate sources $\times 4$ compaction temperatures: 97, 116, 135, and $154°\mathrm{C}\times 6$ repetitions) were fabricated using Superpave gyratory compactor. Volumetric properties of the specimens were evaluated. The results showed that the warm mix processes were effective to improve the volumetric properties of rubberized mixes at a certain range of compaction temperatures.