The potential for alternative materials in pavement construction

Abstract

The current materials used in pavement construction were developed in the 1930s but materials development has not kept pace with increasing traffic demands since this time. This report considers the potential for alternative materials that could offer greater performance in a pavement and meet current transport demands. In order to determine if there were opportunities for alternative materials, the performance of the current materials and associated design methodologies were reviewed. This review found that the current materials have extremely variable performance, with life spans ranging from 1 year to over 20 years and often fail due to insufficient strength in the current materials. Considering this, two key failure scenarios responsible for the majority of failures where identified: Scenario 1 – underlying material fails due to poor load spreading of the upper layers and Scenario 2 – where the upper layers fail through lack of strength or flexibility. By applying standard materials selection processes to consider materials that work under both of these scenarios it was found that wood, waste plastics and steel were options that could be considered as alternative pavement materials. It was found that three potential material configurations could be considered under each of these scenarios: homogenous materials, alternative asphalt matrices to bitumen and sandwich panels. The alternative materials outperformed the current pavement materials in terms of strength. Comparisons with the stiffness of the conventional pavement materials showed that the alternative materials were not as favourable in design methods that only consider the load spreading ability of the material (high stiffness). Field trials confirmed that materials with lower stiffness but much higher strength could offer greater performance than the current pavement materials and should be considered as alternative options to the current pavement materials.