WHO THOUGHT RECYCLED ASPHALT SHINGLES (RAS) NEEDED TO BE LANDFILLED: WHY NOT BUILD A ROAD?

The University of Waterloo’s Centre for Pavement and Transportation Technology, CPATT, is committed to working with public and private sector partners to develop sustainable technologies. Recycled Asphalt Shingles (RAS) is a product that contains approximately 30% asphalt cement by mass weight. Sources of RAS include trimmings from shingle insulation and decommissioned shingle roofs. Reuse of these materials leads to financial savings through avoidance of disposal costs and reduction of the amount of virgin asphalt binder required in HMA. This paper presents results from a recent study involving Miller Paving Limited, CPATT, and Materials Manufacturing Ontario (MMO). In addition École de Technologie Superieure (ETS) in Montreal was involved in the project as a subcontractor to CPATT, carrying out some of the sample testing (1). In order to measure the performance of mixes which incorporate RAS a laboratory study was performed in the John J. Carrick Pavement Laboratory at the University of Waterloo and ETS. Five asphalt pavement mix designs were considered: 1. Mix 1 (control) -HL8, Virgin Material 2. Mix 2 -HL8, 20% RAP Material 3. Mix 3 -HL8, 20% RAP Material, 1.4% Shingles 4. Mix 4 -HL8, 20% RAP Material, 3.0% Shingles 5. Mix 5 -HL8, 3.0% Shingles To compare the various mix designs the dynamic modulus test, resilient modulus test, Thermal Stress Restrained Specimen Tensile Strength Test (TSRST), and French wheel rutting test were run for all five mix designs. The dynamic modulus test was used to measure the elastic properties of the mixtures, an indicator of how a mix will perform over a range of loading and temperature scenarios. The resilient modulus test provides an indication of the fatigue and thermal cracking potential as well as the quality of materials employed in the asphalt mixture. The TSRST assesses the thermal cracking resistance of a mix design while the French wheel rutting test estimates the rutting susceptibility of a mix. Overall the results are very encouraging and have also involved several field placements. Initial analysis of these field placements will also be presented (1)