Semnan University Press Journal of Transportation Infrastructure Engineering 2423-5350 11 2 2025 06 22 Investigating Mode I and Mode II of Fracture Toughness of Asphalt Concrete Containing Steel Slag Powder at Low Temperature Investigating Mode I and Mode II of Fracture Toughness of Asphalt Concrete Containing Steel Slag Powder at Low Temperature 21 42 9571 10.22075/jtie.2025.36844.1714 FA Shahin Shabani Associate Professor in Road and Transportation, Department of Civil Engineering, Payame Noor University, North Tehran Branch, I. R. Iran. Mohammadreza Malek PhD Student in Road and Transportation, Department of Civil Engineering, Payame Noor University, North Tehran Branch, I. R. Iran. Mahmoudreza Keymanesh Professor in Road and Transportation, Department of Civil Engineering, Payame Noor University, North Tehran Branch, I. R. Iran. Journal Article 2025 02 08 Various waste and recycled materials are used in concrete mixtures to produce green building materials, and among them, steel slag is a favorite material that can be used as a partial replacement for natural stone aggregates. In this study, the effect of adding steel slag powder as a filler on the Mode I and Mode II fracture toughness of hot mix asphalt (HMA) was investigated. A semicircular bending specimen with a vertical edge crack was used for the tests. Different HMA mixtures containing 0, 3, and 5 wt.% steel slag filler were prepared using the gyratory compaction method with a void ratio of 3%. Mode I and Mode II fracture toughness tests were performed using symmetric and asymmetric half-disk loading at two low temperatures of -12 °C and -24 °C. According to the results, by adding steel slag powder and increasing its percentage for both temperatures, the values of KIC and KIIC increase, but the values of KIC and KIIC increase more and more significantly with decreasing temperature. For each mixture and temperature, the fracture toughness of Mode II was lower than KIC so that KIIC / KIC fluctuates in a small range from 0.8 to 0.87. These results show good agreement with the predictions of each of the conventional fracture criteria of basic stress and basic energy. Various waste and recycled materials are used in concrete mixtures to produce green building materials, and among them, steel slag is a favorite material that can be used as a partial replacement for natural stone aggregates. In this study, the effect of adding steel slag powder as a filler on the Mode I and Mode II fracture toughness of hot mix asphalt (HMA) was investigated. A semicircular bending specimen with a vertical edge crack was used for the tests. Different HMA mixtures containing 0, 3, and 5 wt.% steel slag filler were prepared using the gyratory compaction method with a void ratio of 3%. Mode I and Mode II fracture toughness tests were performed using symmetric and asymmetric half-disk loading at two low temperatures of -12 °C and -24 °C. According to the results, by adding steel slag powder and increasing its percentage for both temperatures, the values of KIC and KIIC increase, but the values of KIC and KIIC increase more and more significantly with decreasing temperature. For each mixture and temperature, the fracture toughness of Mode II was lower than KIC so that KIIC / KIC fluctuates in a small range from 0.8 to 0.87. These results show good agreement with the predictions of each of the conventional fracture criteria of basic stress and basic energy. https://jtie.semnan.ac.ir/article_9571_2fcab9cb2472ce935e002dedd6e11f0a.pdf