Rutting Resistance of Asphalt Concrete Mixtures that Contain Recycled Asphalt Pavement

Abstract

This study evaluated the rutting resistance of plant-produced asphalt concrete (AC) mixtures in the laboratory. Nineteen plant-produced AC mixtures were used; these mixtures contained reclaimed asphalt pavement (RAP) amounts that ranged from 0% to 25%. Tests on the mixtures included the dynamic modulus (|E*|) test at multiple temperatures and the flow number (FN) test at 54°C to characterize stiffness and rutting resistance, respectively. Mixtures that contained no RAP showed |E*| values comparable to those that contained 25% RAP in most cases. For most of the 19 mixtures tested, mixtures with lower FNs either contained no RAP, contained 25% RAP, or had PG 64-22 as the design binder grade. Mixtures that contained moderate amounts of RAP (10% and 15%), regardless of design binder grade, had higher FNs than mixtures with either high or low RAP amounts. Statistical analysis showed that the RAP amount was the most significant factor to affect rutting resistance in the mixtures studied. A linear inverse relationship between RAP and FN appeared to describe the data well. As the RAP amount increased, a downward trend occurred in both effective binder content (Pbe) and rutting parameter (G*/sin δ). The effect of RAP on FN was unexpected, because it showed the rutting resistance to decrease with increased RAP. Possible reasons might have been the use of softer asphalt binder in mixtures with higher RAP and the observed decrease in both Pbe and G*/sin δ with increased RAP amounts. More rutting-related mechanistic studies are needed of AC mixtures that contain RAP.

Laboratory Compaction Study and Mechanical Performance Assessment of Half-Warm Mix Recycled Asphalt Mixtures Containing 100% RAP

“…Nonetheless, the addition of high RAP contents in asphalt mixtures typically tends to improve the resistance to permanent deformation as a result of the physical hardening and chemical aging (i.e., because of the evaporation of the lighter oil fractions in the bitumen) suffered by the asphalt binder during its service life. Analogous results for mixes containing high and total rates of RAP and additives have been found and contrasted by multiple authors [74,75,76,77,78,79]; whilst the results reported by other authors are rather less conclusive, in the sense that mixtures manufactured at low temperatures and emulsified bitumen are typically characterized by having a lower rutting performance than that of the conventional HMA mixtures [15].…”

Sustainability Assessment of Green Asphalt Mixtures: A Review

“…Additionally, in the literature, there is an inconsistency about the percentage of actual blending between RAP and virgin binders. For example, although some studies have accepted a complete mixing of aged and virgin binder [76,86,87] others have considered partial mixing between them [80,88,89]. Therefore, it is highly recommended to keep usage of RAP in the recycled mixtures to relatively low values due to inability to accurately characterize combined binder properties of recycled mixtures.…”

Evaluation ofin situRAP binder interaction in asphalt mastics using micromechanical models

“…There have been extensive research projects on the use and environmental benefits of this material in asphalt paving (Federal Highway Administration [FHWA] 1993, Bukowski 1997, McDaniel and Anderson 2000, Copeland 2011). Likewise there have been many studies, which evaluate the performance of RAP-modified asphalt concrete mixtures (Huang et al 2004, Shah et al 2007, Hou et al 2010, Apeagyei et al 2011, Loria et al 2011, Li and Gibson 2013. This reference list is by no means limited as dozens or more studies exist, but they do convey some generally consistent findings;…”