Cracking performance evaluation of BMD surface mixtures with conventional and high RAP contents: insights from accelerated pavement testing program

The Balanced Mix Design (BMD) has emerged as a promising approach for mitigating cracking in high reclaimed asphalt pavement (HRAP) mixtures. This study evaluated the cracking performance of a control asphalt mixture and five BMD-optimized asphalt surface mixtures. The mixtures featured various RAP contents, two binder performance grades, a recycling agent, and a warm mix asphalt additive. The analysis integrated continuous longitudinal strain monitoring from Accelerated Pavement Testing (APT), cracking surveys, and laboratory tests. To quantify APT-measured cracking performance, three primary response phases were identified from the continuous strain monitoring. Residual strain was used to determine the initiation of cracking, and deformation uniformity was employed as a data quality indicator. The findings from strain analysis matched APT cracking surveys. Laboratory tests on field cores confirmed no structural damage for the evaluated mixtures, except for a 60% RAP section. All other BMD mixtures demonstrated better cracking resistance over the control mixture, with HRAP BMD mixtures (>30% RAP) outperforming conventional RAP mixtures (≤30% RAP). Correlation analysis between APT and BMD tests examined and supported the corresponding laboratory test thresholds. This study enhanced insights into pavement performance monitoring and highlighted the efficacy of the BMD concept in optimizing the design of HRAP mixtures.