@article{isied_mocelin_preciado_vestena_underwood_kim_castorena_2024, title={Mechanical Properties and Performance of Mixtures Containing a High Level of Recycled Materials That Are Designed Using Alternative Approaches}, volume={4}, ISSN={["2169-4052"]}, url={https://doi.org/10.1177/03611981241238228}, DOI={10.1177/03611981241238228}, abstractNote={ Using recycled asphalt material (RAM) in asphalt mixtures is very common among transportation agencies. With the recent development of balanced mix design methods, it is becoming more important to understand how to optimize mixture performance by offsetting the adverse effects of RAM. In this paper, mixtures from three different sources were adjusted according to the availability adjusted mix design (AAMD) and corrected optimum asphalt content (COAC) methods. Three control mixtures containing RAM, three mixtures containing no RAM, five mixtures designed according to the AAMD method (two of which had 50% reclaimed asphalt pavement content), and two mixtures adjusted using the COAC-based approach were evaluated. Both asphalt mixture performance tester experiments and index tests were used in this study to evaluate material-level indicators of cracking and rutting resistance. Additionally, pavement performance simulations were carried out using AASHTOWare Pavement ME and FlexPAVETM to assess how the observed material-level differences led to differences in structural-level pavement performance. Both the AAMD and COAC methods improved cracking measures. However, the results suggest that the additional virgin binder added through the COAC method without any adjustments to the aggregate structure can have negative consequences for the rutting performance measures. In addition, the mixture and pavement performance results suggest that the AAMD method is a rational approach for including recycled binder availability in mix design procedures to promote improvements in the cracking performance of mixtures by controlling the volumetric properties and the aggregate structure of the mix without having a detrimental effect on rutting resistance. }, journal={TRANSPORTATION RESEARCH RECORD}, author={Isied, Mayzan and Mocelin, Douglas Martins and Preciado, Jaime and Vestena, Pablo and Underwood, B. Shane and Kim, Y. Richard and Castorena, Cassie}, year={2024}, month={Apr} }
 @article{isied_williams iii_saleh_kuchiishi_underwood_kim_2024, title={Mechanical Properties and Performance of Mixtures with the Same Volumetric Classification}, volume={4}, ISSN={["2169-4052"]}, url={https://doi.org/10.1177/03611981241240764}, DOI={10.1177/03611981241240764}, abstractNote={This study investigates the variations in performance among mixtures that are designed for use with the same traffic classification and whether a single mixture class index–volumetrics relationship (IVR) can be applied to all mixtures within that classification. Three surface mixtures, which are intended to serve traffic levels of 3–30 million equivalent single axle loads, were sourced from different regions in North Carolina: the coast; Piedmont; and the mountains. Dynamic modulus, cyclic fatigue, and stress sweep rutting tests were conducted using the asphalt mixture performance tester. Pavement performance simulations were performed using AASHTOWare Pavement ME Design for fatigue cracking predictions and FlexPAVE™ for permanent deformation predictions. The findings indicate substantial differences in mechanical properties, performance indices, and pavement performance among the mixtures despite having similar volumetric properties. The study also shows that an IVR calibrated for a mixture cannot be used to predict the performance of other mixtures within the same mixture classification as the tested mixture. This research highlights the need for restructuring the mixture classification system so that it is based on mixture performance rather than on volumetric design, with the ultimate goal being a performance-based or related specification to eliminate the limitations introduced by the use of volumetric properties.}, journal={TRANSPORTATION RESEARCH RECORD}, author={Isied, Mayzan and Williams III, Nathaniel Reuben and Saleh, Nooralhuda F. and Kuchiishi, Kazoo and Underwood, B. Shane and Kim, Y. Richard}, year={2024}, month={Apr} }
 @article{mocelin_isied_castorena_2023, title={Influence of reclaimed asphalt pavement (RAP) and recycled asphalt shingle (RAS) binder availability on the composition of asphalt mixtures}, volume={426}, ISSN={["1879-1786"]}, url={https://doi.org/10.1016/j.jclepro.2023.139156}, DOI={10.1016/j.jclepro.2023.139156}, abstractNote={Reclaimed asphalt pavements (RAP) and recycled asphalt shingles (RAS) are incorporated in the production of new asphalt mixtures to reduce cost, waste, and the consumption of virgin materials. The use of recycled asphalt materials (RAM) is limited by controlling agencies due to the uncertainties regarding their impacts on the volumetric composition and long-term performance of the asphalt mixtures. Recycled binder availability (RBA), which reflects the proportion of the recycled binder that is available to blend with virgin asphalt in an asphalt mixture, is currently neglected by the majority of mix design methods adopted by highway agencies, despite complete RBA being considered an unrealistic scenario. An incorrect assumption of the RBA in mixture design has important consequences on the inferred asphalt mixture volumetric properties, and consequently on the performance. A recently created method, so-called Availability Adjusted Mix Design (AAMD), proposes a revised interpretation of the volumetric properties of asphalt mixtures and design of the aggregate structure on the basis of partial RBA caused by agglomerations of RAM particles. The AAMD method is used in this study to evaluate the impacts of RBA on the volumetric properties of a diverse set of surface asphalt mixtures. The impacts of the RBA on the inferences of asphalt mixture composition are assessed for each mixture and the viability of using fixed RBA values for RAP and RAS sources in the state of North Carolina is assessed by comparing the inferred asphalt mixture composition yielded from the source-specific RBA versus the average RBA of the pool of recycled materials studied. The results show that the volumetric properties change considerably as a function of the assumed RBA, and the use of the AAMD becomes crucial for mixtures containing as little as 15 percent RAP and/or 4 percent or RAS. The use of a fixed RAS RBA value, calibrated as the average of a representative set of RAS stockpiles, versus the source-specific values has negligible impacts on the inferred volumetric properties of mixtures containing permissible RAS contents in North Carolina. Conversely, the use of source-specific RAP RBA values is recommended, which can be quantified through comparative sieve analysis of RAP and recovered RAP aggregate.}, journal={JOURNAL OF CLEANER PRODUCTION}, author={Mocelin, Douglas Martins and Isied, Mayzan Maher and Castorena, Cassie}, year={2023}, month={Nov} }
 @article{mocelin_isied_alvis_kusam_underwood_kim_castorena_2023, title={Laboratory Performance Evaluation of Alternative Approaches to Incorporate Recycled Binder Availability into Mixture Design Procedures}, volume={4}, ISSN={["2169-4052"]}, url={https://doi.org/10.1177/03611981231161601}, DOI={10.1177/03611981231161601}, abstractNote={ There is currently uncertainty in how to properly account for partial recycled binder availability within asphalt mixture design procedures so that content of recycled asphalt materials (RAM) can be maximized while still achieving good performance. This study evaluates and compares two alternative approaches to consider partial availability in mixture design: availability adjusted mix design (AAMD) and corrected optimum asphalt content (COAC). The AAMD method revises the calculation of volumetric properties by considering unavailable binder as part of the bulk aggregate volume and uses the RAM gradation to design the aggregate structure. In the COAC method, a mixture is first designed following the conventional Superpave procedures and then a specified increase to the virgin asphalt content is made. Two “control” mixtures containing RAM are evaluated that were originally designed according to the standard Superpave method. Alternative designs were prepared according to the COAC and AAMD methods while maintaining the RAM content in the respective control mixture. Baseline virgin mixtures and one mixture designed following the AAMD method with higher reclaimed asphalt pavement (RAP) content were also prepared. The cracking and rutting performance of the resultant mixtures was evaluated. The results show that the AAMD and COAC approaches lead to an improved cracking performance compared with the control mixtures even for the mixture designed with AAMD at a higher RAP content. However, the mixture designs prepared according to the COAC method presented increased rutting whereas the AAMD mixtures remained at the same level as their respective control mixture. }, journal={TRANSPORTATION RESEARCH RECORD}, author={Mocelin, Douglas Martins and Isied, Mayzan Maher and Alvis, Maria Carolina Aparicio and Kusam, Abhilash and Underwood, B. Shane and Kim, Y. Richard and Castorena, Cassie}, year={2023}, month={Apr} }