@article{mocelin_isied_costa_castorena_2024, title={Availability adjusted mix design method as a tool to mitigate the adverse effects of RAP on the performance of asphalt mixtures}, volume={422}, ISSN={["1879-0526"]}, url={https://doi.org/10.1016/j.conbuildmat.2024.135813}, DOI={10.1016/j.conbuildmat.2024.135813}, abstractNote={The use of high percentages of reclaimed asphalt pavement (RAP) in asphalt mixtures offers economic and environmental advantages. However, state agencies place limits on RAP usage to avoid its indiscriminate use without a full understanding of its long-term performance implications. To achieve a more informed and rational use of higher RAP contents, it is essential to quantify recycled binder availability (RBA) and incorporate it into asphalt mixture design. The current design methods often assume complete RBA, leading to less durable mixtures. Standardized mixture design methods fail to rigorously account for the effects of RBA on the volumetric composition of asphalt mixture. Recently, the availability adjusted mixture design (AAMD) method was developed to address these issues by explicitly considering partial RBA in the interpretation of mixture volumetric properties and accounting for the role of RAP agglomerations on aggregate structure. This study tests the hypothesis that the AAMD method can mitigate the adverse performance consequences of RAP through the control of 'available' volumetric and effective binder properties. This was achieved by comparing virgin and RAP mixtures designed with similar 'available' volumetric properties according to the AAMD method. Additionally, control mixtures with RAP contents ranging from 20 to 35 percent were compared to AAMD mixtures with similar 'available' volumetric properties designed with the same RAP content and with 50 percent RAP. The collective results demonstrate that the AAMD method effectively mitigates negative performance consequences of RAP by controlling the 'available' volumetric and effective binder properties.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Mocelin, Douglas Martins and Isied, Mayzan Maher and Costa, Rafaella Fonseca da and Castorena, Cassie}, year={2024}, month={Apr} }
 @article{mocelin_kim_2024, title={Balanced Mix Design Plus for Mixtures that Contain Recycled Asphalt Pavement}, ISSN={["2169-4052"]}, DOI={10.1177/03611981241245687}, abstractNote={Recent efforts have been made to include mixture performance tests at the mix design stage using so-called “balanced” mix design (BMD). This paper evaluates the use of two mixtures that contain intermediate and high recycled asphalt pavement contents in the context of a BMD approach referred to as balanced mix design plus (BMD+). BMD+ utilizes the dynamic modulus, cyclic fatigue, and stress sweep rutting tests and mechanistic models and has three tiers of design based on the amount of performance testing required. As part of the BMD+ approach, index–volumetrics relationships (IVRs) and performance–volumetrics relationships (PVRs) based on the four-corner concept were developed for the two mixtures and verified using the performance data from seven other volumetric conditions. The developed PVRs were used to perform BMD+ Tier 3 analysis of the two mixtures, whereas the IVRs based on two points at the target air void content of 4% were used to conduct BMD+ Tier 2 analysis. The results indicate that the use of BMD+ Tier 2, which requires performance tests at only two conditions and without pavement simulations, yields longer lasting mixtures compared with Tier 1, which follows the Superpave volumetric mix design method. It was also found that Tier 3 requires more testing and pavement simulations but leads to even further gains in predicted life duration compared with Tier 2.}, journal={TRANSPORTATION RESEARCH RECORD}, author={Mocelin, Douglas Martins and Kim, Y. Richard}, year={2024}, month={May} }
 @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{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} }
 @article{keshavarzi_mocelin_kim_2022, title={A Composite Model for Predicting the Coefficient of Thermal Contraction for Asphalt Concrete Mixtures}, volume={50}, ISSN={["1945-7553"]}, DOI={10.1520/JTE2021003}, number={1}, journal={JOURNAL OF TESTING AND EVALUATION}, author={Keshavarzi, Behrooz and Mocelin, Douglas and Kim, Y. Richard}, year={2022}, month={Jan}, pages={1–23} }
 @article{spadoni_ingrassia_mocelin_kim_canestrari_2022, title={Comparison of asphalt mixtures containing polymeric compounds and polymer-modified bitumen based on the VECD theory}, volume={349}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2022.128725}, abstractNote={The ‘dry’ method that can be used to produce modified asphalt mixtures is a less expensive, less energy-consuming, and faster process than the well-established ‘wet’ method. Moreover, the dry method allows the incorporation of hard plastics, even those plastics obtained from waste products. Although researchers agree that the dry method can improve the stiffness and rutting resistance (i.e., high-temperature performance) of asphalt mixtures, they have conflicting opinions regarding mixture fatigue and cracking resistance. In this regard, this paper aims to evaluate, through the application of viscoelastic continuum damage theory, the fatigue behavior of two compound asphalt mixtures that have been modified using the dry method. One of the studied compounds is composed of plastomeric polymer and the other is composed of waste plastic with the addition of graphene. A reference mixture containing polymer-modified bitumen (representing the wet modification method) was used for comparison. The experimental program involved dynamic modulus tests and uniaxial cyclic fatigue tests of laboratory-compacted specimens and cores extracted from full-scale field test sections. The test results from the laboratory-compacted specimens and field cores were input to FlexPAVETM for pavement performance simulations. Under the same volumetric conditions, the three dense-graded mixtures broadly had comparable stiffness and fatigue resistance values at the material level. However, in the pavement-level simulations, the reference mixture exhibited much less damage after 30 years of service than the compound mixtures. Concerning the field test track, the air void contents of the mixtures varied due to workability issues related to the presence of the compounds. Optimum performance was obtained for asphalt layers that could be characterized by an intermediate stiffness level that ensured an adequate load distribution without negative consequences for the mixture’s fatigue resistance and thermal resistance.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Spadoni, Sara and Ingrassia, Lorenzo Paolo and Mocelin, Douglas and Kim, Y. Richard and Canestrari, Francesco}, year={2022}, month={Sep} }
 @article{mocelin_castorena_2022, title={Impacts of recycled binder availability on volumetric mixture design and performance}, volume={3}, ISSN={["1477-268X"]}, url={https://doi.org/10.1080/10298436.2022.2046276}, DOI={10.1080/10298436.2022.2046276}, abstractNote={ABSTRACT The use of reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) in asphalt mixtures is a routine process. Recycled binder availability reflects the proportion of the total recycled binder in a given recycled asphalt material (RAM) that is available to blend with the virgin binder. Studies show that agglomerations of adhered RAM particles preclude complete availability. However, the Superpave volumetric mixture design methods adopted by the majority of state agencies assume complete availability. This study makes use of a sieve analysis method and tracer-based microscopy analysis to quantify recycled binder availability. Revisions to asphalt mix design procedures to account for partial availability are proposed, including consideration of the unavailable binder as part of the bulk aggregate volume and the use of the RAM gradation (i.e. black curve) rather than the recovered aggregate gradation (i.e. white curve) to design the mixture’s aggregate structure. Three high RAM content ‘control’ mixtures that were originally designed under the assumption of complete recycled binder availability are redesigned according to the proposed approach. The redesigned mixtures had notably higher virgin binder content than the control mixtures. The redesigned mixtures also had significantly better cracking resistance than the control mixtures while still meeting permanent deformation requirements.}, journal={INTERNATIONAL JOURNAL OF PAVEMENT ENGINEERING}, author={Mocelin, Douglas M. and Castorena, Cassie}, year={2022}, month={Mar} }
 @article{keshavarzi_mocelin_kim_2021, title={Predicting Thermal Stress Restrained Specimen Test Fracture Temperatures Using the Dissipated Pseudo Strain Energy Criterion}, volume={147}, ISSN={["2573-5438"]}, DOI={10.1061/JPEODX.0000236}, abstractNote={AbstractThermal cracking is the predominant failure mode for asphalt pavements constructed in regions with severe air temperature drops or significant daily temperature variations. The thermal stre...}, number={1}, journal={JOURNAL OF TRANSPORTATION ENGINEERING PART B-PAVEMENTS}, author={Keshavarzi, Behrooz and Mocelin, Douglas and Kim, Youngsoo Richard}, year={2021}, month={Mar} }
 @article{saleh_keshavarzi_rad_mocelin_elwardany_castorena_underwood_kim_2020, title={Effects of aging on asphalt mixture and pavement performance}, volume={258}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2020.120309}, abstractNote={This study investigates the effects of long-term aging on pavement performance under realistic traffic and thermal conditions. Using the NCHRP 09-54 aging procedure, a systematic study of the effects of aging on asphalt mixture linear viscoelastic and fatigue properties was conducted. The computational engine of FlexPAVE™ V1.1was modified to run more realistic pavement performance simulations. Results suggest that the effect of aging on pavement performance is evident only when simulations employ more realistic traffic and climatic conditions. In the absence of thermal conditions, the effect of changes in mixture properties on pavement performance is not significant.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Saleh, Nooralhuda F. and Keshavarzi, Behrooz and Rad, Farhad Yousefi and Mocelin, Douglas and Elwardany, Michael and Castorena, Cassie and Underwood, B. Shane and Kim, Y. Richard}, year={2020}, month={Oct} }
 @article{nafisi_mocelin_montoya_underwood_2020, title={Tensile strength of sands treated with microbially induced carbonate precipitation}, volume={57}, ISSN={["1208-6010"]}, DOI={10.1139/cgj-2019-0230}, abstractNote={ During large earthquake events where bending moments within soil cements are induced, the tensile strength of cemented soil may govern the deformational behavior of improved ground. Several studies have been conducted to assess the tensile strength of artificially cemented sands that use Portland cement or gypsum; however, the tensile strength of microbially induced carbonate precipitation (MICP)-treated sands with various particle sizes measured through direct tension tests has not been evaluated. MICP is a biomediated improvement technique that binds soil particles through carbonate precipitation. In this study, the tensile strength of nine specimens were measured by conducting direct tension tests. Three types of sand (coarse, medium, and fine) were cemented to reach a heavy level of cementation (e.g., shear wave velocity of ∼900 m/s or higher). The results show that the tensile strength varies between 210 and 710 kPa depending on sand type and mass of carbonate. Unconfined compressive strength (UCS) tests were performed for each sand type to assess the ratio between tensile strength and UCS in MICP-treated sands. Scanning electron microscopy (SEM) images and surface energy measurements were used to determine the predominant failure mode at particle contacts under tensile loading condition. }, number={10}, journal={CANADIAN GEOTECHNICAL JOURNAL}, author={Nafisi, Ashkan and Mocelin, Douglas and Montoya, Brina M. and Underwood, Shane}, year={2020}, month={Oct}, pages={1611–1616} }