The effect of using capsules containing waste mineral oil on self-repairing of long-term aged bituminous hot mixtures

Nowadays, the importance of hot bituminous mixtures in terms of transportation is quite high. Bituminous hot mixes become brittle with the increase in stiffness due to the increasing traffic load and climatic conditions over time. This situation causes cracks and deterioration in the pavement. Therefor, it is necessary to observe the bituminous mixture layers regularly, and to carry out maintenance and repair activities. However, this may not always be possible for economic or technical reasons. For this reason, the idea of self-healing hot mix with bitumen has gained importance in recent years. Studies on self-healing of hot bituminous mixtures are grouped under three main headings. These; It is a method of induction heating, microwave heating and capsule use. The newest of these methods is the addition of capsules to the hot bituminous mixture. In this method, as a result of the crack encountering the capsule, the capsule breaks and releases the restorative material to the crack area, resulting in healing. Within the scope of the study, waste mineral oil, which is released after the maintenance of the vehicles, was used as a reparative material in the capsules. Capsules providing optimum conditions have been produced. Capsules were added to the mixtures in four different ratios (0.25%; 0.50%; 0.75% and 1.00% by weight of aggregate). Four different cures (24 hours at 25°C; 48 hours at 25°C; 24 hours at 40°C; 48 hours at 40°C) were applied to the bituminous hot mixtures. Three-point bending fatigue test and FTIR test were applied to BSK specimens. In addition, the volumetric properties of the mixture samples were determined in order to evaluate the effect of capsule addition on the mechanical properties of the mixtures. In the study, the effect of capsule amount, curing time and temperature on the mixtures was investigated. As a result of the experiments, it has been seen that increasing the amount of capsule increases the oil release and the healing rate, but decreases the mechanical performance by reducing the fatigue life. The increase in curing time and temperature increases the healing rate.