The effect of warm additive on the properties and behavior of an asphalt binder

Use of warm asphalt mix has been recently receiving a great attention because it allows decreasing production and distribution temperatures about 30–40°C by either reducing bitumen viscosity or enhancing mixture performance. These mixes also have other advantages such as a low pollution, reduced fuel consumption, and more implementation seasons. Despite these benefits, there is a constant concern about the performance of these mixes under the conditions such as permanent deformation, fatigue cracking, and low-temperature cracking. In the present study, two types of bitumen modifiers including liquid additive and Sasobit were used to adjust rheological properties of bitumen. After conducting the required tests on bitumen specimens prepared using these two additives and comparing the results obtained from two common and Strategic Highway Research Program tests under aged and nonaged conditions, it was revealed that, considering the viscosity of bitumen, these additives improve bitumen performance at ambient temperatures. Besides, the results indicate the improvement in rutting criteria (G^*/sinδ) and fatigue criterion (G^*×sinδ).