Investigating the Performance Characteristics of Asphalt Binder and Asphalt Concrete Mixes Containing Waste Iron Powder

A strategy that has significant positive effects on the environment and economy is the addition of waste materials to new roads and highways. The purpose of this study is to investigate how adding the Waste Iron Powder (WIP) affects concrete mixes and asphalt binder. WIP was used as an additive of asphalt cement and asphalt concrete mixtures with different percentages (0, 2.5, 5, 7.5, 10%) by volume of asphalt. Conventional asphalt binder tests were conducted, including penetration, ductility, softening point, flash and fire point, and specific gravity. Also, Superpave performance grading (PG) tests were carried out: Rotational viscosity (RV), Rolling thin-film oven (RTFO), Pressure aging vessel (PAV), Dynamic shear rheometer (DSR), and Bending beam rheometer (BBR). Marshall stability and flow, dynamic creep, and fatigue (indirect tensile modulus test) were conducted on the modified asphalt concrete mixtures. The conventional tests indicate an improvement when WIP is incorporated. Superpave tests that were conducted on the modified asphalt binder showed an improvement in rutting resistance. Moreover, the dynamic creep test showed that the resilient modulus and creep stiffness have been enhanced compared to conventional asphalt concrete mixtures and they reached their optimum values at 7.5% WIP content. The fatigue test showed an enhancement in the fatigue cracking resistance of the modified asphalt concrete mixture by increasing the resilient modulus values and decreasing the total horizontal recoverable deformation, thus resulting in pavement life improvement. As a result, it can be concluded that adding (5–7.5%) of WIP to asphalt cement improves the performance of road pavement structures. Using 7.5% WIP by volume of binder resulted in enhancement in both asphalt binder and asphalt concrete mixes. This WIP content agrees with the Marshall specifications. WIP mostly improves the asphalt cement and asphalt concrete mixture properties which are related and influenced by moderate to high temperatures.