Laboratory evaluation of the mechanical properties of plant-produced warm-mix asphalt mixtures

This paper presents a laboratory evaluation of plant-produced asphalt mixtures containing the control hot-mix asphalt (HMA) and four warm-mix asphalt (WMA) technologies: an organic additive (Sasobit®) and three foaming processes (Advera®, low-emission asphalt, and Gencor). These asphalt mixtures were produced using a single binder performance grade (PG 64-22) and 9.5-mm nominal maximum aggregate size Superpave mix design compacted to 75 design gyrations. Dynamic modulus (E*), flow number, and Hamburg wheel–track tests were utilised to evaluate the mechanical properties of the asphalt mixtures. The PG of the asphalt binders containing the WMA technologies was also verified. In addition, their rheological properties were evaluated using shear modulus master curves and multiple stress creep recovery tests. It was found that the asphalt binder containing Sasobit® technology increased the continuous high-temperature binder grade by 6°C and measured higher elastic properties. In general, the asphalt mixture prepared with Sasobit® technology and the control HMA mixture measured higher stiffness than those prepared with the other WMA technologies and measured the highest dynamic modulus rutting parameter and fatigue cracking parameter. In addition, these mixtures demonstrated increased resistance to rutting and moisture damage. Statistical analysis indicated that the binder rheological properties, WMA dosage rates, and production temperatures influenced the performance of the WMA mixtures.