Estimating Allowable RAP in Asphalt Mixes to Meet Target Low Temperature PG Requirements

With the increase of construction price and the awareness of environmental protection, RAP (recycled asphalt pavement) has become more widely used to conserve resources and reduce cost. Estimating the RAP binder properties and its allowable percentage in asphalt mixes with and without changing binder grade has, therefore become more and more important. The currently used methods of extracting and recovering asphalt binder with solvents are not reliable enough to estimate RAP binder properties. The inclusion of RAP in the asphalt mix can improve its resistance to rutting while it may greatly jeopardize its resistance to thermal cracking. Therefore, this research work focuses on developing a new analysis procedure to estimate the allowable percentage of RAP binder in asphalt mixes based on binder low temperature properties. This paper introduces an analysis procedure to achieve this goal based on a recently developed method of testing RAP mortars. The analysis procedure requires BBR testing results of the fresh binder and two different RAP mortars as an input. This input is analyzed in different steps, and the output of the procedure is the allowable limits of RAP for different targeted PG grades. A spread sheet was developed to carry on the entire analysis. The procedure was verified by comparing estimations of RAP binder properties with known properties of an artificial RAP made with PAV aged binder. In addition the effect of choosing different gradations and asphalt contents for producing and testing mortars were evaluated. The results show high potential for fairly accurate estimation of amount of RAP that could be allowed without changing PG low temperature grade using simple procedures using the BBR.


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  • Accession Number: 01328008
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 18 2011 3:01PM