Effects of using reclaimed asphalt shingles as partial replacement of roadway base course and infrastructure backfill materials

Abstract

The province of Prince Edward Island (PEI) among other provinces is trying not only to save money, but also help the environment by recycling materials for construction applications that would otherwise end up in a landfill. Reclaimed asphalt shingles (RAS) were investigated to see if the material would be a suitable partial replacement for the base course in roadway construction and backfilling materials. Mixtures of RAS and the natural aggregate (currently used for this type of construction by PEI) were tested for characteristics (e.g. density, strength, permeability, etc.) to validate the potential to replace up to 30% of natural aggregates with RAS. The laboratory test results such as standard Proctor and California Bearing Ratio (CBR) demonstrated that the addition of RAS to the natural aggregates can significantly decrease its performance. This indicates that only a small amount (< 10%) of RAS could be considered to be used in both roadway construction and infrastructure backfilling. RAS also hindered the permeability test results with up to a 96% reduction at a 30% replacement ratio. This document outlines the testing methods and results found in mixtures with 10%, 20% and 30% RAS replacement. It was found that the mixtures would still meet the specified physical requirements however, an exponential decrease in the strength, and a reduction in the cohesion and internal friction angle were observed with the increase of RAS content.