Evaluating the Performance of the Asphalt Mixes Containing Reclaimed Asphalt Pavement by Considering the Effect of Silo Storage Time

• Published in: Journal of testing and evaluation 2020-01, Vol.48 (1), p.18-34
• Main Authors: Kadhim, Hawraa, Baaj, Hassan
• Format: Article
• Language: English
• ISSN: 0090-3973; 1945-7553
• DOI: 10.1520/JTE20180957

The use of reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) has been increasing in the last few decades because of its cost benefits and because of a compelling need to preserve the environment and natural resources. It is commonly assumed that HMA containing RAP (HMA-RAP) has an improved resistance to permanent deformation (rutting) and decreased resistance to the fatigue cracking. This is due to the fact that asphalt binder contained in the RAP has been oxidized over the years and is typically stiffer than virgin asphalt binder. However, during the production stage of the HMA-RAP, the blending between aged and virgin asphalt binders would be incomplete or partial, which would lead to heterogeneous distribution of the aged and virgin asphalt binders within the asphalt mix with RAP. Therefore, the purpose of this article is to evaluate the effect of silo storage on the blending mechanism between virgin and RAP asphalt binders and the impact that this would have on performance of the mix. Two plant-produced asphalt mixes (HL-3 and HL-8), typically used in the province of Ontario for surface and base courses in flexible pavements, were considered in this study. The mixes were designed with 15 and 30 % RAP, respectively, and the samples were collected immediately after the production (0 h) or at different silo storage times (1, 4, 8, and 12 h). The temperatures of the collected materials were closely monitored and recorded. The findings of this research indicated that silo-stored samples exhibited some improvement in their rutting and fatigue resistance. The examination of the dynamic modulus master curves indicated that the rheology of the mixes evolved with silo storage and that blending between the aged and the virgin binders has been improved.