Development of self-heating tack coat for bonding prefabricated rollable asphalt materials to existing pavement structure

Prefabricated rollable asphalt materials (PRAM) can be bonded to the existing pavement structure (EPS) using either the cold bonding method or the thermal bonding method. However, the cold bonding method is sus-ceptible to environmental factors, and the thermal bonding method has poor construction safety and conve-nience. The above problems limit the application of the PRAM. The objective of this study is to develop a self-heating tack coat (SHTC) consisting of an exothermic compound (EC) and a binder as an alternative to the cold bonding method and the thermal bonding method. To obtain greater bonding performance between the PRAM and EPS, the thermal characteristics of the EC and the binder as well as the interlaminar shear strength (ISS) between the PRAM and the EPS were investigated for determination of the optimal material composition of the SHTC. First, three types of EC were selected with four dosages, and their exothermic characteristics were investigated. Second, the endothermic characteristics of selected binders were studied during the heat release of the EC. Then, the ISS between the PRAM and the EPS was measured using the direct shear test when the material composition of SHTC was different. According to the results of these tests, the exothermic compound III (EC-III) was found to be the preferred EC type with an optimum dosage of 0.2 kg/m2, and #70 neat asphalt was found to be the preferred binder type. Under these conditions, the ISS between the PRAM and the EPS reached a maximum of 0.7 MPa. Finally, a comprehensive comparison was made between the proposed method and the traditional bonding method in terms of the ISS, the construction cost, the CO2 emission, and the construction time. The results showed that the SHTC developed in this study can be used as an alternative to traditional bonding methods.