Abstract: Adhesion between asphalt and recycled aggregate is studied by conducting tensile tests of their macroscopic interface and a theoretical analysis allowing for the microscopic surface energy theory. We measure the microscopic contact angle of the two materials at room temperature, using four combinations of probe liquids, and select the optimal combination. Then we conduct macroscopic tensile tests on the specimens at the temperatures of 5 °C, 10 °C, 15 °C and 20 °C, respectively for asphalt Karamay 70, asphalt Karamay 90, and Shandong modified asphalt. The results show that microscopically, through correlation coefficient analysis, the most suitable probe solution combination can be selected for analysis, and surface energy and adhesion work between different asphalt types and recycled aggregate are obtained, which is able to reflect their interfacial adhesion. Macroscopically, the tensile force between asphalt and recycled aggregate gradually decreases with rising temperature, following an inversely proportional relationship. The asphalt-aggregate adhesion changes with the change in the asphalt type, taking the largest value with asphalt Karamay 90, which is also being verified by the microscopic test.

Key words: adhesivity, recycled aggregate, tensile test, contact angle, surface energy