Comparative study of different materials for insulated pavement in cold regions

Abstract

Pavements constructed on frost-susceptible subgrade layers are prone to deterioration from freezing in cold regions. A thermal insulation layer above the frost-susceptible subgrade layer in a pavement structure could effectively mitigate the deterioration due to frost action. The objective of study was to evaluate the thermal insulation performance of different insulating materials experimentally and numerically. Therefore, five large-scale pavement boxes, including one uninsulated pavement and four insulated pavements using different materials (i.e., XPS board, tire chips, foam glass aggregates (FGA), and foamed concrete), were constructed. The thermal insulation performance was studied under constant freezing condition and freeze-thaw cycles where the temperature profile of pavements was monitored. A finite element model was developed by considering the transient heat flow and the associated latent heat of fusion in the unbound granular layers. Correspondingly, the numerical simulation was conducted to extrapolate the temperature profile for pavement structures made by different insulating materials. The experimental results show that the XPS and FGA have the best overall insulation performance, followed by foamed concrete and tire chips. Results of the numerical simulation suggest that to achieve an equivalent level of insulation performance as a 5 cm thick XPS board under the same freezing conditions, insulating materials such as tire chips layer, FGA layer, foamed concrete layer, or recycled concrete aggregate should have insulation layer thicknesses of 40 cm, 25 cm, 30 cm, or 68 cm, respectively. In terms of cost-benefit analysis, the foamed concrete insulated pavement is the most expensive option, followed by uninsulated pavement, insulated pavements using FGA, tire chips, and XPS. This study highlights the critical role of the insulating material and the insulation layer thickness in cost-benefit thermal insulation for pavements in cold regions.