Design, construction, and evaluation of energy-harvesting asphalt pavement systems

Abstract

Energy-harvesting pavements, one of which is the Hydronic Asphalt Pavement (HAP) system, have been proven to be both more durable and sustainable than conventional pavement systems. A HAP consists of a system of connected pipes embedded within the asphalt pavement which function to extract or reject heat from/into the pavement via a circulating fluid. Three large-scale systems were designed and constructed in the field: a control section, a regular HAP section, and a section containing a HAP coupled to a horizontal ground heat exchanger (GCHAP). The field data showed that neither the HAP section nor the GCHAP section were able to substantially decrease the pavement surface temperature. However, both GCHAP and HAP were able to decrease the asphalt temperature at a depth of 2.5 cm below the surface by a magnitude of around 10°C. Another key finding of this study shows that increasing the conductivity of a flexible pavement asphalt layer, rather than increasing the conductivity of the embedded pipes, significantly enhances the effectiveness of the HAP system.