Mechanical Behavior of Synthetic Zeolite-Warm Mix Asphalt Containing Sulfur Waste as a Sustainable Filler

The use of warm asphalt mixtures has been increasing continuously in recent times as a promising alternative, as it leads to lowering the manufacturing and application temperatures, and thus it saves energy, reduces fuel consumption and reduces emissions. On the other hand, the possibility of using waste materials in the creation of heated mixtures increases the positive effects on the environment and the economy because using waste instead of virgin (raw) materials helps to lower extraction costs and ease landfill strain. The feasibility of employing sulfur waste (SW) instead of the conventional mineral filler (CaCO₃) for warm mix asphalt (WMA) mixtures is explored in the current study. The WMA mixes were produced by using synthetic zeolite (SZ) with a concentration of 5 percent (by weight of asphalt cement). Four WMA mixes were made, three of which were made using SW at different percentages of 4, 5, and 6 percent (by weight of aggregate), and a reference one using regular filler (CaCO₃) at 5 percent (by weight of aggregate). Marshall stability, Marshall quotient, indirect tensile strength at 25 and 60 °C, tensile strength ratio, rutting resistance in Kim test and Semi-Circular Bending (SCB) Fracture test were the mechanical parameters that were assessed. The results of the tests showed that a slight change occurred in the Marshall stability of the SW mixtures, while a significant decrease in the flow values and air voids of the warm mixtures containing SW compared to the WMA control mixture. As a result, the Marshall quotient values for these mixtures increased, and thus the SW mixtures meet the requirements of ASTM for Marshall properties deservedly, the deformation strength is also optimized for SW mixtures. Perhaps the most important improvement is in the tensile strength ratio (TSR), where the TSR values increased by 36.94%, 50.84% and 54.46% for the SW mixtures SW4%, SW5% and SW6% respectively, compared with the reference WMA, it was concluded that it is possible to use sulfur waste in the production of warm mixtures, as it contributes to improving the properties and its transportation cost is lower compared to the traditional filler (CaCO₃).