Evaluation of asphalt binder and mixture properties that incorporate reclaimed asphalt pavement

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Date

2018-05-04

Authors

Lee, Sang Ki, M.S. in Engineering

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Abstract

Several private and public agencies are exploring ways in which the use of reclaimed asphalt pavement (RAP) can be increased in the construction of new pavements. However, such an increase must not come at the expense of reduced durability or life cycle cost. The use of RAP is often accompanied by some form of adjustment to the virgin binder that is being used. In Texas, the current practice of incorporating RAP is controlled by a simplified table that lists a substitute binder grade and recycled binder ratio (RBR) when RAP is incorporated in a mix. There are a few shortcomings with this simple approach of specifying a maximum ratio: (1) it does not address the potential difference in the quality of recycled binders from RAP, (2) it may result in the use of substituted binders with little or no polymer (elastomer) and (3) it does not account for the influence of recycling agents. The goal of this study was to evaluate the change in performance of binders and mixtures using different grades of virgin binder and percentages of RAP. Two different Job Mix Formulae (JMF) and corresponding materials were obtained from asphalt plants in the state of Texas. A test matrix was developed to evaluate binders and mixtures with different ratios of recycled binder to virgin binder and different ratios of RAP to virgin material, respectively. The results from this study show that addition of RAP or recycled binder (from RAP) results in an increase in stiffness and resistance to rutting, which was expected. However, the resistance to cracking showed mixed results. The test results also show that the properties of the recycled binder from RAP can vary significantly with source and have a drastic effect on the properties of the binder and mixture.

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