Evaluation of the performance of warm mix asphalt in Washington state

Study of Surfactant Additives for the Manufacture of Warm Mix Asphalt: From Laboratory Design to Asphalt Plant Manufacture

“…In addition, it is clear that the lower the manufacturing temperature, the lower the stiffness modulus. Whilst this could be associated with lower compaction of the specimens (particularly in the case of the mixtures manufactured at 120 °C), the decrease in modulus could also be due to lower ageing of the bitumen during the manufacturing process, since the temperature is reduced by 20-45 °C in reference to the case of the HMA, and therefore, the short-term stiffening of the bitumen is lower [14,19]. Thus, the mixtures manufactured at 120 °C showed higher reduction in stiffness modulus, obtaining quite similar values for the different additives, while in the case of the mixtures manufactured at 145 °C, the additive A2 led to a slight increase in bearing capacity, which could also be influenced by higher density values, according to the results described previously.…”

“…The additive A2 was therefore selected as the most appropriate for studying the optimization of the WMA design, with a view to its later use in a real asphalt plant. Figure 5 compares the workability of WMA with 0.5% of additive As the decrease in stiffness modulus in the WMA could be due to lower stiffening of the bitumen, lower resistance to rutting could be also obtained [14]. Figure 4 displays the resistance to permanent deformation for each mixture in order to show the effectiveness of these chemical additives in reducing the stiffening of the asphalt mixture whilst avoiding higher rutting deformations.…”

“…Thus, the mixtures manufactured at 120 • C showed higher reduction in stiffness modulus, obtaining quite similar values for the different additives, while in the case of the mixtures manufactured at 145 • C, the additive A2 led to a slight increase in bearing capacity, which could also be influenced by higher density values, according to the results described previously. As the decrease in stiffness modulus in the WMA could be due to lower stiffening of the bitumen, lower resistance to rutting could be also obtained [14]. Figure 4 displays the resistance to permanent deformation for each mixture in order to show the effectiveness of these chemical additives in reducing the stiffening of the asphalt mixture whilst avoiding higher rutting deformations.…”

“…This indicates the ability of these chemical additives to reduce the manufacturing temperature of asphalt mixtures, which decreases stiffening whilst allowing the WMA to maintain a bearing capacity and resistance to permanent deformations that is comparable to conventional HMA. As the decrease in stiffness modulus in the WMA could be due to lower stiffening of the bitumen, lower resistance to rutting could be also obtained [14]. Figure 4 displays the resistance to permanent deformation for each mixture in order to show the effectiveness of these chemical additives in reducing the stiffening of the asphalt mixture whilst avoiding higher rutting deformations.…”

“…Therefore, in-depth studies are required to provide useful knowledge about the suitability of these additives for application in pavement construction as well as their capacity to improve the mechanical performance of asphalt mixtures manufactured at low temperatures [3]. Moreover, most of the work on WMA with chemical additives has focused on laboratory analysis, with relatively few studies conducted in a real life field setting [14][15][16][17]. The latter type of study is essential to demonstrate the effectiveness of reproducing these WMAs in real asphalt plants for their application in pavements for roads.…”