Fundamental property evaluation of styrene monomer modified warm-mix asphalt concrete

Recently, many warm-mix asphalt (WMA) mixtures are produced at approximately 120 degrees C, which is 40 degrees C lower than normal HMA processing temperature. This heat reduction is considered as a big achievement in asphalt paving industry. They used normal asphalt binders and WMA additives to make the mixes less at warm temperatures. However, this paper deals with a different WMA concept by using a styrene monomer (SM) for melting down the asphalt, making liquid asphalt beforehand. The objective of this study is to make the SM-modified WMA mixtures at 95 degrees C, which is more than 60 degrees C reduction of HMA temperature, and show strength properties of WMA concrete, as a new asphalt technology, in comparison with normal HMA mixes at 160 degrees C or higher. The 6% of SM was selected as the optimum content at which the mix was blended well using a normal lab mixer and compacted well by gyratory and roller-press compactors at 95 degrees C. Various property test results of the 6% SM-modified bitumen mixture were similar to those of conventional bitumen mixtures. Therefore, it was possible to use SM-modified bitumen for WMA production at much lower temperature than normal WMA.