Investigation of mechanical properties of hot mix asphalts containing self-healing capsules

Due to environmental and structural effects, various deterioration, especially crack formation, occurs in hot mix asphalts. Damage, due to crack formation, can reach levels that may threaten driving comfort and safety if not intervened. Therefore, scientists have focused on the self-healing feature that is inherent in the asphalt but cannot reach the desired levels since it is not possible to provide sufficient temperature and time. Various methods have been designed to accelerate the self-healing phenomenon and strengthen its impact. Commonly used among these methods are Induction Method, Microwave Method and Microcapsule method. The aim of the induction and microwave method is increase the surface and internal temperature of the hot mix asphalt and provide healing. In the microcapsule method, briefly, capsules containing rejuvenator are preparing, these capsules adding to the hot mix asphalt during the construction process, the rejuvenator in the mixture is releasing and heals the crack as a result of contact with the crack. Within the scope of the thesis, two different types of rejuvenators, waste vegetable and waste mineral oil, were added to the hot mix asphalt at different rates (0.25%, 0.50%, 0.75%, 1.00% by weight of aggregate). The vegetable oil used in the study was supplied as waste sunflower oil in the kitchens, the mineral oil was obtained as the waste engine oil released after periodic maintenance of the cars. In order to evaluate the effect of capsule addition on the mechanical properties of hot mix asphalts, the volumetric properties of the mixture samples were determined, followed by Marshall stability and flow, tensile strength ratio, indirect tensile stiffness module, indirect tensile fatigue and dynamic creep tests. In addition, semicircular samples were obtained and capsules with different proportions were added to these samples. Then, resistance to crack propagation were tried to be evaluated in different approaches. As a result of the mixture experiments, it has been determined that the use of waste oils as rejuvenators will provide economic and environmental benefits, and the optimum capsule content in the mixture has been determined to be 0.5% by weight of the aggregate.