Performance of Asphalt Mixtures with High Recycled Contents Using Rejuvenators and Warm-Mix Additive: Field and Lab Experiments

To improve the cracking resistance of asphalt mixtures with high recycled asphalt pavement (RAP) and reclaimed asphalt shingles (RAS) contents, one approach is to use a recycling agent (RA) (i.e., rejuvenator) to potentially restore the performance properties of the aged binder. This project was conducted to evaluate the effect of recycling agents on the laboratory test results and field performance of mixes with high recycled contents. The field study consisted of three mixtures: A control mix containing 20% RAP and no RA, and two experimental mixes with different rejuvenators containing 25% RAP and 5% RAS. The control mix was produced at a typical hot-mix asphalt (HMA) production temperature [149 degrees C (300 degrees F)], while the experimental mixes were produced as warm-mix asphalt (WMA) [129 degrees C (265 degrees F)]. Two rejuvenators were used in the study. This paper presents data collected during the construction of the test sections, laboratory test results, and early field performance (approximately two years). Compared to the control mix, both the experimental mixes with 25% RAP plus 5% RAS showed similar rutting resistance but significantly lower resistance to cracking based on lab test results and field performance data. The lab test results, especially for overlay test (OT) and Illinois flexibility index test (I-FIT), are in agreement with the field cracking performance of these mixes-the experimental mixes with OT cycles below 125 and flexibility indexes below three cracked within two years in the field. Thus, further research can be conducted to refine these criteria for use in mix design and/or quality control (QC)/quality assurance (QA) to avoid premature mixture cracking in the future.