Stress-strain response analysis of demolition wastes as aggregate base course of pavements

The sustainable construction approach by utilizing recycled aggregates has increasingly been the focus of highway construction industries and local road authorities in recent years. The efficient usage of recycled aggregates for sustainable construction is owed to more than a decade of extensive experimental research aiming to remove uncertainties in the properties and performance of recycled aggregates in transport infrastructures. Nevertheless, a lack of knowledge exists about the stress-strain response of the pavement structures constructed using recycled aggregates. The main goal of this study was to propose a response analysis approach to incorporate the repeated load triaxial (RLT) test results as a Level 1 MEPDG input parameter in a well-established pavement analysis software named FlexPAVETM. In this approach, the aggregate base course was divided into ten sublayers of equal thickness. Three different constitutive resilient modulus (Mr) models were utilized to determine the Mr of each sublayer corresponding to the stress levels achieved at that sublayer. Modeling the pavements in FlexPAVETM by assigning the corresponding Mr to the sublayers resulted in a more accurate stressstrain response compared to the conventional linear elastic analysis approach. This approach provides a more realistic and, accordingly, more accurate analysis of the behavior of unbound aggregates in pavements. The secondary goal of this study was to investigate the stress-strain response of pavements with aggregate base courses made of three types of recycled construction and demolition wastes, being recycled concrete aggregate (RCA), crushed brick (CB), and waste excavation rock (WR). The resilient properties of the demolition wastes were determined through repeated load triaxial (RLT) testing. A typical pavement profile consisting of asphalt surface course, aggregate base course, and an A6 type of natural soil as subgrade was modeled using FlexPAVETM. The response analysis was undertaken following the proposed sub layered approach. Under the loading conditions adopted in this research, with bulk stresses <185 kPa, CB and RCA exhibited a superior Mr response compared to the conventional virgin materials, while WR showed an inferior behavior.