Abstract

This paper presents the first analysis on the evaluation of the thermophysical and heating performance of self-healing asphalt mixtures with different contents of steel wool fibres for their potential use as a solar radiation absorbing material in an asphalt solar collector prototype. With this aim, four different dense-graded asphalt mixtures were prepared using the same aggregate gradation and bitumen content, but with different content of steel wool fibres: 0%, 2%, 4%, and 6% by total volume of bitumen. Physical and thermal properties, such as bulk density, air void content, thermal conductivity, specific heat capacity, and thermal diffusivity were evaluated on the asphalt test specimens. Steel wool fibre distribution inside the asphalt mixture samples was also evaluated by X-ray computed microtomography. Moreover, the thermal behaviour of a solar collector prototype, using an asphalt mixture with 4% of steel wool fibres as a solar radiation absorbing material was exposed to solar radiation conditions simulated in laboratory using a novel direct normal irradiance experimental model. This model was developed by the authors to experimentally simulate the maximum and minimum irradiance conditions for the city of Concepcion in Chile. The main results showed that self-healing asphalt mixtures with steel wool fibre addition reduced their thermophysical properties, explained by an increment in their total volume and due to the fibre distribution inside the samples. Additionally, this study proves that asphalt mixtures with 4% of steel wool fibres can be potentially used as a radiation absorbing material, transmitting the infrared radiation from the asphalt pavement surface to the water stored inside it. In short, this study provides the first assessment on the fundamental thermophysical variables of self-healing asphalt mixtures with metallic fibres, with the purpose of exploring their future use for energy harvesting applications.