Empirical transfer functions for foam glass aggregates insulation used in flexible pavement layered systems

Abstract

Pavement design in cold regions is challenging due to the difficult conditions of soils, humidity, and temperatures. Insulation layers have been identified as a suitable solution for these conditions. Due to their unique engineering properties, foam glass aggregates (FGAs) are a promising material for use as an insulating granular layer in pavement design. However, understanding their mechanical performance is critical for predicting long-term layer and pavement behavior. In this laboratory study, an empirical transfer function was developed using an environmental and heavy vehicle simulator and an experimental pavement built in an indoor test pit. The study aimed to determine the allowable number of load repetitions for an FGAs insulation layer and to develop an empirical transfer function that can be used as part of a mechanistic-empirical pavement design procedure. This article proposes a linear relationship between permanent deformation, the number of load cycles, and the equivalency factor between the effect of resilient strain, or vertical stress, and allowable damage. The proposed empirical transfer functions allow defining an allowable number of load repetitions for a characteristic resilient strain or vertical stress and an allowable damage. The allowable damage can be modulated with respect to road classification, and a damage value of 0 % to FGAs layer can be considered as a safety factor. The findings of this study provide valuable insights into the use of FGAs as an insulating granular layer in pavement design in cold regions.