Investigation of Long-term Performance of Warm Mix Asphalts Containing EAF Steel Slag

Due to sustainable development, environmental concerns caused by air pollution, expansion of development projects, and limitations of mineral aggregates, reduction of construction temperature of asphalt mixtures and use of secondary materials as substitute for aggregate materials is inevitable. In this research, long-term performance of warm asphalt mixtures containing steel slag was investigated. Limestone aggregates and steel slag of Electric Arc Furnace (EAF) were the main materials and Sasobit was used as an additive in manufacturing warm asphalt mixtures. Using 1.5% Sasobit, with respect to bitumen’s weight, decreased temperature of the asphalt mixtures by 20 °C. In order to simulate short-term and long-term aging of asphalt samples, AASHTO R35 and AASHTO R30 standards were used. Sasobit was mixed with asphalt by conventional mixer and high-shear mixer. Traditional and SHRP tests conducted on mixtures indicated that Sasobit is insensitive to mixing conditions. Performance of asphalt samples was evaluated by Marshall stability test, resilient modulus test, indirect tensile strength test, moisture susceptibility test and dynamic creep test. Finally, quantitative growth of the results for each sample, with respect to hot calcareous asphalt mixture, was presented. In general, using slag as calcareous substitute caused higher aging of asphalt mixtures. Also, hot asphalt samples, as compared to warm asphalt mixtures, were more sensitive to aging. As warm asphalt mixtures containing EAF steel slag, with respect to other asphalt mixtures, have shown long-term and short-term performance, therefore, they are recommendable.