Influence of Laboratory Mixing Procedures on Volumetric and Mechanical properties of RAP Mixtures


The primary goal of this study was to assess the effectiveness of specific laboratory mixing procedures in simulating the production of plant-produced hot mix asphalt (HMA) mixtures with high reclaimed asphalt pavement (RAP) content. Three distinct methods for incorporating the RAP material into the mixing process were examined. The first method consisted of heating and mixing the virgin aggregate, virgin asphalt binder, and RAP material at the appropriate mixing temperature for the virgin asphalt binder. The second method consisted of superheating the virgin aggregates according to the National Asphalt Pavement Association (NAPA) recommendations, with the virgin asphalt binder heated to the appropriate temperature and the RAP material introduced dry and at the ambient temperature. Last, the third method was similar to the second procedure with the exception of adding the RAP material wet at the ambient temperature. Mixing temperatures were examined over the duration of the mixing process for each method. This provided insight into how effectively the virgin aggregate is transferring heat to the RAP material. Additionally, a short-term oven-aging analysis was utilized to determine the appropriate aging time in the laboratory to replicate the aging experienced by the plant-produced mixtures. Last, compacted samples were created for each mixing method, as well as for the plant-produced laboratory-compacted mixtures, to analyze the volumetric properties and mechanical properties using the dynamic modulus. Based on the data generated in this study, the most appropriate method was recommended to be instituted in the laboratory for mixing HMA mixtures containing RAP material because of its simplicity and its close results to the plant-produced mixtures.


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E. Hajj, M. Souliman, P. Sebaaly, and M. Barton, "Influence of Laboratory Mixing Procedures on Volumetric and Mechanical Properties of RAP Mixtures," Advances in Civil Engineering Materials 2, no. 1 (2013): 485-505.

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