Analysis of reclaimed asphalt blended binders using linear and nonlinear viscoelasticity frameworks
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ORIGINAL ARTICLE
Analysis of reclaimed asphalt blended binders using linear and nonlinear viscoelasticity frameworks Bhaskar Vajipeyajula
. K. Lakshmi Roja . Eyad Masad . Kumbakonam R. Rajagopal
Received: 15 May 2020 / Accepted: 3 September 2020 RILEM 2020
Abstract This paper presents a comprehensive analysis of blended asphalt binders extracted from mixtures that contain various amounts of reclaimed asphalt pavements (RAP). The analysis is performed within a thermodynamically consistent non-linear viscoelastic (NVE) modeling framework, which has the advantage of accounting for the contributions of each of the constituents (i.e. virgin binder and RAP binder) to the response of the blended binder. In order to calibrate and validate the NVE model, the RAP blended binders were subjected to different testing protocols: frequency sweep, multiple stress creep and recovery, repeated creep and recovery with multiple stress levels, random creep and recovery, and stress relaxation. For the binders used in this study, linear viscoelasticity (LVE) was suitable to model the frequency sweep and multiple stress creep and recovery data, but it did not capture the repeated creep and recovery with multiple stress levels results that involved higher stress and strain levels. The NVE model, on the other hand, was successful in describing the repeated creep and recovery with multiple stress levels results. The validation was achieved by B. Vajipeyajula (&) K. R. Rajagopal Department of Mechanical Engineering, Texas A&M University, College Station, TX 77840, USA e-mail: [email protected] K. L. Roja E. Masad Department of Mechanical Engineering, Texas A&M University at Qatar, Doha, Qatar
comparing the NVE model predictions with the random creep and recovery and stress relaxation test results. Finally, the paper recommends a new method, based on the parameters of the NVE model, to evaluate the rutting resistance of blended asphalt binders. Keywords Reclaimed asphalt pavement Rutting Frequency sweep Multiple stress creep recovery Random creep and recovery Stress relaxation Nonlinear viscoelastic modelling
1 Introduction The increasing demand for asphalt materials and the depletion of natural resources (virgin aggregates and asphalt binder) have motivated the use of recycled asphalt pavements (RAP) in the construction of new pavements. Significant research has been carried out with regard to determining the RAP binder properties and its influence on the rheological properties of the blended asphalt binder [1–4]. Various researchers have quantified the rutting performance of RAP blended asphalt binders using experimental methods that utilize aspects of linear viscoelasticity (LVE) theory [5–8]. The two test parameters that are typically used to quantify rutting are G = sin d (G is the dynamic modulus and d is the phase angle) measured using a dynamic test and Jnr (creep compliance)
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measured using the multiple stress and creep recovery test [9–12]. Jnr
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