Healing of Transverse Joints Fillers in Concrete Pavement Using Induced Heating by Electromagnetic Radiations

Proper and timely maintenance of concrete pavement plays a decisive role in increasing the life of these pavements. Joint plain concrete pavement is a type of concrete pavement used for roads. One of the important parts of this type of pavement is the joints created in it. The use of joints to provide conditions for expansion and contraction in concrete pavements and thus reduce stresses due to changes in weather conditions (temperature and humidity), friction, and facilitate the manufacturing process. Due to the fact that the joint in the joint plain concrete pavements is a weakened area for the conduction of cracks from unforeseen areas of the concrete slab to it, the entry of water and other materials into it causes penetration into the underlying layers of the slab to prevent penetration. Joint Sealants are used in these areas. Hot applied bitumen sealant is one of the most common sealants used in joints, which is based on bitumen. One of the key factors in the longevity of concrete pavement is the proper functioning of the joint and joint sealant. The adhesion and cohesion failures are two main damage types in the hot-applied bituminous joint sealants in concrete pavement joints. The mentioned failures are caused by the contraction of concrete pavement under the temperature drop and fluctuation as well as vertical displacement due to passing traffic load. The failure in joint sealant causes elimination of water proofing feature in joints leading to penetration of water into the sublayers. Subsequently, the presence of water in sublayers results in pumping of water under the concrete slab, which leads to other failures types, such as faulting, blow up, corner break. The resealing of joint sealant is the commonly used approach to repair the joints, which takes considerable costs, times and environmental consequences. In recent years, induction heating has attracted substantial attentions among the pavement engineers for innovative applications, specifically for induced healing. The researchers used this method in asphalt mixtures to heal cracks and microcracks. To make the electromagnetic radiations more effective, they used bipolar additives such as activated carbon and carbon black to raise the temperature of the asphalt mixture and cover the cracks and microcracks. In this study, the induction heating and induced healing of asphalt binder was carried out in reaping the joint sealant and to recover the cohesion-adhesion failures. To this end, a new testing setup and frame were designed to conduct the tensile test on hot-applied bituminous joint sealant. First, the sealant bitumen was placed between two concrete blocks, and then the specimens were conditioned at low temperatures (i.e. -10 °C, -20 °C, and -30 °C). After conditioning, the tensile under a displacement controlled loading test was carried out until failure point of joint sealant. Subsequently, the broken joint sealants were exposed to the electromagnetic radiation in a microwave machine to heat and heal the joint sealant. Then, the tensile test was again conducted on the specimen until failure point. The results showed that induced healing can recover and heal the joint sealant experienced cohesion-adhesion under contraction loading. This observation indicates that the induced heating is a potential technique to repair the joint sealants in jointed concrete pavements.