Porous asphalt pavements are often used to reduce runoff and improve the highway security. As a result, water may be retained in the internal pore structure of porous asphalt roads. The ability of asphalt material to dry after exposure to water may affect its functionality and durability thus it is important to understand water evaporation process from asphalt.
We have conducted a comprehensive series of water evaporation experiments in porous asphalt material with air void content ranging from 14% to 29%. X-ray Computerized Tomography (CT) scans combined with the state-of-the-art 3D printing technology were employed to quantify the effects of pore structure, topology and pore size distribution on the dynamics of water evaporation from asphalt with well-characterised properties. The evaporation experiments were conducted under well-controlled external conditions (humidity and temperature). Macroporosity, pore size distribution, conductivity, water retention curve and tortuosity of asphalt materials were quantified by means of the high-resolution images obtained by X-ray tomography. Our results suggest that the evaporation rate from the asphalt mixtures studied in the present research is related predominantly to the air void content, pore size distribution and tortuosity. Using the obtained experimental results, a theoretical model was proposed to estimate the evaporation rate from porous asphalt material under different boundary conditions. Our results and analysis provide new insights about the dynamics of water evaporation from asphalt materials as well as offer new quantitative tools for estimating the evaporation rate from asphalt.
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