Evaluation of Laboratory Performance and Structural Contribution of Cold Recycled Versus Hot Mixed Intermediate and Base Course Asphalt Layers in New Hampshire

Abstract

Depending on the local conditions and structural design of the pavement, multiple asphalt concrete layers including base, intermediate, and wearing courses are used. Typically, the base and intermediate layers have larger aggregate sizes and lower total asphalt binder contents as compared with the wearing course. Recently, cold recycled (CR) asphalt mixtures have gained attention as an alternative to the typical base, and to some extent intermediate courses, because of economic and environmental advantages. Challenges with CR include the potential high variability of recycled asphalt pavement (RAP) and lack of knowledge in relation to structural contribution and long-term performance of such layers. This study investigates four different types of CR and four hot mixed plant-produced asphalt mixtures (three intermediate courses and one base course) that are typical mixtures used in New Hampshire. The laboratory performance evaluation is conducted through the resilient modulus (Mr), complex modulus (E*), semi-circular bend and direct tension cyclic fatigue (S-VECD) tests. Pavement performance prediction is carried out using the results from S-VECD approach in the FlexPAVETM software. The test results indicate that the performance of CR is highly affected by the amount of oil distillate percentage in the emulsion as well as the amount of recovered binder in the RAP. While having a relatively lower rutting resistance capability, the CR mixtures maintained an acceptable fatigue performance. As compared with CR mixtures, hot mixed intermediate and base course mixtures indicated better rutting performance while having lower resistance to cracking.

Assessment of Interlocking Concrete Block Pavement with By-Products and Comparison with an Asphalt Pavement: A Review

“…Based on the research by Nemati et al [118], the design parameters, cross-section details, and the FlexPAVE analysis showed the evolution of cracking with the number of failed elements (DF = 1) for 240 months (20 years). Furthermore, the FlexPAVE simulation results met expectations concerning AP's design properties.…”

Generalized Methodology to Develop Mechanistically Informed Asphalt Mixture Layer Coefficients for AASHTO 1993 Pavement Design Approach

“…Complex modulus testing was performed in accordance with the AASHTO T342 standard. The results from the complex modulus testing were analyzed using the complex modulus-based rutting index parameter (CMRI) as shown in Equation 4 (11,15). This parameter is developed based on two critical points on the master-curves: the reduced frequency associated to the peak phase angle and the reduced frequency associated with the Hamburg Wheel Tracking Test (HWTT) testing condition used in the New England region (45°C and 0.866 Hz).…”