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Laboratory Testing of Vancouver HMA Mixes Containing Recycled Asphalt Shingles


Recycled asphalt shingles (RAS) contain asphalt cement and high quality aggregate that may be a useful supplement to natural, virgin aggregates and asphalt cements. RAS originating from recycled construction material can be crushed and added to asphalt mixes, similar to reclaimed asphalt pavement (RAP). Scraps from asphalt shingles production that are commonly considered as waste material have been used in pavements in Ontario for more than 10 years as an alternative to sending them to landfills. Metro Vancouver is focusing primarily on post-consumer waste shingles, meaning those that have already provided a service life as a roofing material. Metro Vancouver retained Golder Associates to carry out a study on using RAS as an additive in asphalt mixes through sustainability development impacts, environmental impacts, and technical performance. The technical phase of this study focuses on performance evaluation of hot-mix asphalt (HMA) mixes containing RAS. There were six mix types included in the study: a conventional binder course mix from British Columbia used here as a control mix; a mix with 15.0 percent RAP; and mixes with a rejuvenator and with 3.0 and 5.0 percent RAS, and 15.0 percent RAP and 3.0 and 5.0 percent RAS. The asphalt mix performance testing includes: dynamic modulus; resilient modulus; resistance to rutting in the Asphalt Pavement Analyzer (APA); fatigue endurance in a four point bending beam test; and low temperature cracking susceptibility in the Temperature Stress Restrained Specimen Test (TSRST). This paper presents the results of the first three tests and includes an analysis and discussion related to the behavior of the mixes. Besides the obvious effect of mix hardening when RAS and/or RAP are added, it also looks at the impact of the addition of a rejuvenator. Based on the results of the laboratory testing, field trials will be carried out. The main objective of the study is to determine what the maximum acceptable amount of RAS and RAS/RAP combination is that will not have negative impact on the performance of asphalt pavements. It will then form the base for the development of paving specifications for asphalt with RAS additives. 

Conference Paper Details

Session title:
Ludomir Uzarowski
Hana Prilesky
Esther Berube
Vimy Henderson
Rabiah Rizvi