Structural Performance Assessment of Geothermal Asphalt Pavements: A Comparative Experimental Study

This paper introduces shallow geothermal systems as a potential solution for improving the thermo-mechanical performance of asphalt under extreme climate events. With the recent changes experienced in the climate, earlier infrastructure failure can be expected, predominantly for temperature-sensitive flexible pavements. With that in mind, the efficiency of geothermal systems in terms of heating and cooling was comprehensively argued in many studies. However, very limited studies discussed the structural performance of geothermal pavements. This study conducted a comparative experimental study to assess the change in the compressive and flexural strengths of asphalt under extreme heating and cooling conditions and to evaluate the change in asphalt structural performance due to integrating different types of geothermal pipes into the asphalt structure. This comparative analysis employed thirty-three asphalt specimens with and without copper and polyvinyl chloride (PVC) geothermal pipes. The results of this study show that the geothermal pipes negatively affected the compressive strength of the asphalt at a normal average temperature. However, their effect was relatively minimal on the asphalt (AC) compressive strength under extreme heating and cooling conditions. In contrast, under three thermal conditions—normal, heating, and cooling temperatures—the flexure strength of the AC was significantly improved by 14.3%, 85%, and 70%, respectively, due to the copper pipe integration into the AC. The study concluded that copper pipes were superior to PVC ones in terms of enhancing the AC structural performance.