Complex modulus and fatigue baviour of recycled hot mix asphalt : laboratory investigation and modelling at the material levels

Abstract

The amount of available RAP (Recycled Asphalt Pavement) material in Canada is considerable and continually increasing, and the use of RAP as a component in new mixes is strongly supported by the asphalt industry. However, the use of mixtures containing RAP has not been investigated in great detail, so it is essential to explore whether this material has a positive effect on the fatigue life of asphalt pavement. Fatigue from repeated traffic loading, is considered one of the major distress occurring in flexible pavement systems. Previous studies have been conducted to understand how fatigue appears in pavement and how to model this phenomenon. However, there are no research studies in this area that works on developing prediction models for mixtures containing RAP. The objectives of this study are to evaluate the impact of the addition of RAP on complex modulus and fatigue, and to modify the fatigue prediction equation accordingly. For that, tension-compression complex modulus tests at various frequencies and temperature were performed, as well as tension-compression fatigue tests. A total of 11 mixes, with one type of RAP, four different percentages of RAP (0%, 15%, 25%, and 40%), one type of Virgin aggregate, and two types of asphalt binders, were made in two different production methods: RAP added Cold or RAP added Hot. Also those mixtures include samples of aged RAP which will be blended with new aggregate and new asphalt materials to produce different recycled mixtures. The results have shown that the dynamic modulus of the recycled mixtures made with RAP added hot show some differences from the control mixture and control mixture incorporating RAP (25% and 40%) were found at the higher and lower test temperatures, but the 15% RAP mixture had dynamic modulus curves similar to that of the control mixture. Fatigue test results show that adding up to 25% RAP had little effect on fatigue performance. However fatigue life increased with the addition of 40% RAP. Fatigue prediction models were improved with considering the inclusion of added RAP up to 25% and up to 40% using the phenomenological approach and presented in verification of the two failure criteria. Those models provide prediction of the fatigue life of the recycled mixtures throughout the results of fatigue tests of the mixture containing no RAP. Mathematical models to predict the fatigue life of the recycled mixture were also developed.

Date	15 Dec 2016
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Alan Carter (Supervisor) & Daniel Perraton (Co-supervisor)