Education

Research Description

Dr. Castorena's research is focused on characterization of asphalt materials. Specifically, her work utilizes multi-scale characterization to develop a fundamental understanding of asphalt binders and their interaction with mineral aggregates. This work aims to improve our methods for asphalt pavement material selection and design. Additionally, she investigates the use of innovative alternative cement binders and asphalt modification technology for improved pavement sustainability.

Publications

Addressing raveling resistance in chip seal specifications

Adams, J., Castorena, C., Im, J. H., Ilias, M., & Kim, Y. R. (2017), Transportation Research Record, (2612), 39–46.

Application of time-temperature superposition principle on fatigue failure analysis of asphalt binder

Wang, C., Castrorena, C., Zhang, J. X., & Kim, Y. R. (2017), Journal of Materials in Civil Engineering, 29(1).

Evaluation of small specimen geometries for asphalt mixture performance testing and pavement performance prediction

Lee, K., Pape, S., Castorena, C., & Kim, Y. R. (2017), Transportation Research Record, (2631), 74–82.

Investigation of proper long-term laboratory aging temperature for performance testing of asphalt concrete

Rad, F. Y., Elwardany, M. D., Castorena, C., & Kim, Y. R. (2017), Construction & Building Materials, 147, 616–629.

Material nonlinearity in asphalt binder fatigue testing and analysis

Safaei, F., & Castorena, C. (2017), Materials & Design, 133, 376–389.

A framework to characterize the healing potential of asphalt binder using the linear amplitude sweep test

Xie, W., Castorena, C., Wang, C., & Kim, Y. R. (2017), Construction and Building Materials, 154, 771–779.

Blending measurements in mixtures with reclaimed asphalt use of scanning electron microscopy with X-ray analysis

Castorena, C., Pape, S., & Mooney, C. (2016), Transportation Research Record, (2574), 57–63.

Identifying fatigue failure in asphalt binder time sweep tests

Wang, C., Zhang, H., Castorena, C., Zhang, J. X., & Kim, Y. R. (2016), Construction & Building Materials, 121, 535–546.

Linking asphalt binder fatigue to asphalt mixture fatigue performance using viscoelastic continuum damage modeling

Safaei, F., Castorena, C., & Kim, Y. R. (2016), Mechanics of Time-Dependent Materials, 20(3), 299–323.

Nanoindentation and atomic force microscopy investigations of asphalt binder and mastic

Veytskin, Y., Bobko, C., & Castorena, C. (2016), Journal of Materials in Civil Engineering, 28(6).

View all publications via NC State Libraries

Grants

Calibration of Structural Layer Coefficients for North Carolina Asphalt Pavements

NC Department of Transportation(8/01/18 - 7/31/20)

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Calibration of Structural Layer Coefficients for North Carolina Asphalt Pavements

Sponsor: NC Department of Transportation

Start Date: 8/01/18

End Date: 7/31/20

Abstract

The North Carolina Department of Transportation (NCDOT) uses the AASHTO Guide for Design of Pavement Structures 1993 to determine the minimum pavement stiffness that ensures pavement longevity. During design, this stiffness is first determined using an iterative design process, charts, or software. Then, the engineer selects materials and layer thicknesses that provide the required stiffness by summing the contributions of individual layers. The contribution from any given layer is calculated by the product of that layer’s thickness and a structural layer coefficient that captures the overall quality and structural benefit of the material. In the NCDOT procedure, the structural layer coefficient for asphalt concrete (AC) is 0.44 (surface and intermediate mixtures) or 0.30 (base mixtures), while other material types are lower, e.g., the structural layer coefficient for unbound aggregate base materials is 0.14. While the NCDOT has had success with these structural layer coefficient values, they are based on a test road constructed and evaluated in one climate zone and with one set of materials. Modern material selection and design have resulted in substantial changes in AC and aggregate base since this time. These improvements have likely resulted in different structural contributions from these materials, which means the structural layer coefficients should be reviewed and possibly changed. Proper characterization of these layer coefficients could result in substantial cost savings to the NCDOT by reducing the required pavement thickness and/or leading to pavements that require less frequent rehabilitation and reconstruction.

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Improving the Design of RAP and RAS Mixtures

NC Department of Transportation(8/01/18 - 7/31/20)

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Improving the Design of RAP and RAS Mixtures

Sponsor: NC Department of Transportation

Start Date: 8/01/18

End Date: 7/31/20

Abstract

The usage of Reclaimed Asphalt Pavement (RAP) and Reclaimed Asphalt Shingles (RAS) in asphalt mixtures has increased significantly in recent years. While increasing recycled material usage has the potential to yield environmental and economic benefits, there is uncertainty in the validity of the current volumetric design and the associated performance of RAP and RAS mixtures. The mixture design procedure currently employed by the NCDOT assumes 100 percent binder contribution from recycled materials. However, it is currently poorly understood to what extent the recycled binder acts as “black rock” as opposed to actually blending with virgin asphalt. The erroneous assumption of complete blending will lead to an underestimation of required virgin asphalt binder content during mixture design and consequently yield mixtures with high cracking susceptibility. In addition, the recycled binder contribution is an important consideration when selecting the virgin binder grade for a mixture. Erroneous assumptions of blending may have negligible effects at low reclaimed binder contents but significant effects at higher contents. Therefore, given the increasing use of higher recycled material content mixtures in practice, an in-depth study is needed to develop an understanding of recycled binder contribution to improve the virgin binder grade selection and volumetric design of RAP and RAS mixtures.

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Ruggedness and Interlaboratory Studies for Asphalt Mixture Performance Tester (AMPT) Cylcic Fatigue test

Federal Highway Administration (FHWA)(9/28/17 - 3/27/20)

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Ruggedness and Interlaboratory Studies for Asphalt Mixture Performance Tester (AMPT) Cylcic Fatigue test

Sponsor: Federal Highway Administration (FHWA)

Start Date: 9/28/17

End Date: 3/27/20

Abstract

AASHTO TP 107 enables the practical, mechanistic performance characterization of asphalt concrete using cyclic fatigue testing in the Asphalt Mixture Performance Tester (AMPT). AASHTO TP 107 was initially developed for the use of 100-mm diameter specimens, which yield a single test specimen per gyratory sample. Recently, a modified version of AASHTO TP 107 was proposed for the testing of 38-mm diameter small specimens that improves the efficiency of specimen fabrication and enables the testing of field cores extracted from as-built pavement layers. The objective of the proposed research is to improve AASHTO TP 107 by conducting ruggedness and interlaboratory studies using both small and large specimens. The ruggedness evaluation will identify controllable experimental factors that significantly affect the test results and to establish limits for their control. The interlaboratory study will lead to precision statements that define the repeatability and reproducibility of small and large cyclic fatigue the test results.

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Use of Rejuvenator Prior to Chip Seal on Aged Flexible Pavement

NC Department of Transportation(8/01/17 - 7/31/19)

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Use of Rejuvenator Prior to Chip Seal on Aged Flexible Pavement

Sponsor: NC Department of Transportation

Start Date: 8/01/17

End Date: 7/31/19

Abstract

Emulsions are used as tack coats to bond hot-mix asphalt layers and in chip seals to bind aggregates. The rate of emulsion application is critical to the performance of both tack coats and chip seals and hence, is an important design factor. Emulsion is often applied to aged flexible pavements in North Carolina. Oxidative aging embrittles asphalt binder near the pavement surface which increases top down cracking and raveling, leaving the pavement surface porous and dry. Consequently, when emulsion is applied to an aged flexible pavement, a portion of the applied emulsion will be absorbed by the existing pavement. To compensate, the current practice is to adjust the required target Emulsion Application Rate (EAR) used in the construction based on visual inspection of the existing pavement surface. This current practice is subjective and visual appearance cannot be tied directly to surface dryness. Therefore, an improved method is needed to inform adjustment of the target EAR during construction to account for emulsion lost to absorption. Improved selection of the design EAR will result in prolonged pavement service life, potentially resulting in significant economic savings.

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Implementation of the Tack Lifter

NC Department of Transportation(3/01/17 - 6/30/18)

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Implementation of the Tack Lifter

Sponsor: NC Department of Transportation

Start Date: 3/01/17

End Date: 6/30/18

Abstract

Emulsions are used as tack coats to bond asphalt concrete layers and as a bonding agent in pavement surface treatments. The emulsion application rate (EAR) is critical to the performance of both tack coats and surface treatments. The EAR can vary longitudinally along the length of paving as a result of fluctuations in distributor speed and flow rates. Currently, the only measure for quality control of the EAR along the length of paving is to measure the change in the volume of emulsion in the distributer tank before and after paving. This practice lacks the ability to quantify local variability in the applied EAR. In addition, the existing paving surface will absorb a portion of the applied emulsion which will be unavailable to act as a bonding agent for aggregate or asphalt concrete placed on top of the emulsion. To compensate, the current practice is to adjust the required target EAR used in the construction based on visual inspection of the existing pavement surface. The current practice is subjective and visual appearance cannot be tied directly to surface dryness.

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Quantifying the Impact of Crack Sealant on Pavement Surface Friction

NC Department of Transportation(8/01/16 - 12/31/18)

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Quantifying the Impact of Crack Sealant on Pavement Surface Friction

Sponsor: NC Department of Transportation

Start Date: 8/01/16

End Date: 12/31/18

Abstract

Crack sealing is a pavement preservation technique used to prevent moisture intrusion into cracked pavements, thereby preventing weakening of underlying layers and reducing the rate of pavement deterioration. However, if crack sealing covers too much of the pavement surface area, it can negatively impact skid resistance, creating a potential safety hazard. Crack sealing may cover too much of a pavement’s surface area if either excessive crack sealant is applied (e.g., overband is too wide) or if the density of cracks sealed on the pavement surface is too high. Current crack sealant specifications do not include provisions to prohibit skid loss. To develop such specifications, research is needed to determine the allowable percentage of pavement surface area that can be occupied by crack sealant without the loss of frictional properties.

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Re-Appraisal of the Specification for Aggregate Base Course (ABC)

NC Department of Transportation(8/01/15 - 12/31/17)

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Re-Appraisal of the Specification for Aggregate Base Course (ABC)

Sponsor: NC Department of Transportation

Start Date: 8/01/15

End Date: 12/31/17

Abstract

The current specification for acceptance of Aggregate Base Course (ABC) materials consists of a band-type gradation specification, which is essentially a “recipe” that dictates the mass percentages of the individual particle sizes constituting the ABC. The “recipe” specification is based on the assumption that the product will achieve the desired engineering performance as long as it meets required gradations and is placed and compacted properly in the field. However, the biggest disadvantage of the “recipe” specification is that it cannot quantify the mechanical behavior of the aggregates under different traffic and weather conditions, which will determine the stress states and moisture variations. Recent developments in mechanistic-empirical pavement design (i.e., Pavement ME Design) utilize mechanical material properties and structure to predict pavement performance, which includes properties of the unbound aggregates. Therefore, understanding the mechanical properties of ABC is critical for prediction of pavement performance, and consequently design. Unfortunately, the current ABC specification is disconnected with the design process and required parameters. A more comprehensive approach to test, evaluate, and accept aggregate base course material is needed. Understanding of the material behavior due to stress conditions and moisture variations is important to ensure adequate pavement performance. Gradation alone is insufficient to adequately capture mechanical properties of different aggregates. Incorporating easy to measure physical characteristics of the ABC (e.g., angularity, shape, and texture) and aggregate packing theory into the material specification will aid in linking easily measured ABC properties to observed mechanical properties. Developing a relationship between the material properties and the mechanical behavior will allow the new specification to be directly related to the design parameters. Additionally, the re-appraisal of the ABC specification should include tests that are practical enough to be used routinely to evaluate the necessary variables. To best meet the objectives of the proposed research, first, a literature review of current practices for ABC specification used throughout the US, identification of critical properties governing ABC mechanical behavior, and state-of-the art test methods to efficiently characterize the identified properties will be conducted. The literature review will be followed by a testing program that focuses on both physical material properties and mechanical behavior of the ABC material. The testing program will be complimented with modeling the ABC material using aggregate packing theory and the discrete element method. The material and behavioral testing and modeling results will be compiled to develop a relationship between the material properties and pavement performance, which in term will be used to propose a new specification for ABC material.

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Renewable Paving Binders from Top-lit Updraft Kilning of Biomass

National Science Foundation (NSF)(6/15/15 - 5/31/19)

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Renewable Paving Binders from Top-lit Updraft Kilning of Biomass

Sponsor: National Science Foundation (NSF)

Start Date: 6/15/15

End Date: 5/31/19

Abstract

The long-term goal of the proposed research is develop a sustainable alternative to asphalt binder in pavements. For an alternative binder to be viable as a replacement to asphalt cement, it must (a) be derived from renewable sources that can be produced economically in mass quantities, (b) require less energy and produce fewer emissions than the production and construction of concrete using current asphalt binder technology, and (c) demonstrate equal or superior performance over asphalt binder. To best meet these objectives, bio-binders will be produced using thermo-chemical conversion of biomass. Biomass feedstock and thermo-chemical conversion operating parameters will be varied in order to link inputs to produce a viable paving binder. Rigorous analyses of bio-binder chemical composition and properties will be conducted to assess the viability of bio-binders produced for use in pavements. In addition, preliminary trials of producing bio-binder – aggregate mixtures will be conducted using conventional laboratory methods for producing asphalt mixtures. Performance testing of bio-binder – aggregate mixtures will be conducted to assess their performance and to link critical bio-binder properties to the resultant performance of mixtures. In addition, life cycle analysis will be conducted to assess the sustainability of bio-binders compared to petroleum-based asphalts.

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Development of Small Specimen Geometry for Asphalt Mixture Performance Testing

National Academy of Sciences(1/01/15 - 6/30/17)

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Development of Small Specimen Geometry for Asphalt Mixture Performance Testing

Sponsor: National Academy of Sciences

Start Date: 1/01/15

End Date: 6/30/17

Abstract

The specific innovation to be developed is a small specimen geometry for uniaxial asphalt mixture dynamic modulus and direct tension fatigue testing in the Asphalt Mixture Performance Tester (AMPT). Two small specimen geometries will be tried: a small cylindrical geometry consisting of 38mm diameter specimens with 100mm height and a small prismatic geometry 25mm thick, by 50mm wide, by 100mm tall. Both uniaxial cyclic, direct tension and monotonic direct tension (constant strain rate) testing for fatigue characterization will be considered. The small specimen geometry will allow for testing individual layers of as-built pavements, allowing for forensic investigations of field performance and performance-based construction quality assurance. In addition, use of small specimens can greatly improve laboratory prepared mixture testing efficiency by allowing for extraction of multiple small test specimens from a single gyratory sample. Fatigue performance evaluation will be facilitated by applying the Viscoelastic Continuum Damage (VECD) mechanics to fatigue test results.

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Comparing Performance of Full Depth Asphalt Pavements and Aggregate Base Pavements in NC

NC Department of Transportation(8/16/14 - 7/31/17)

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Comparing Performance of Full Depth Asphalt Pavements and Aggregate Base Pavements in NC

Sponsor: NC Department of Transportation

Start Date: 8/16/14

End Date: 7/31/17

Abstract

The objectives of the proposed research are: (1) to provide important performance information regarding asphalt base and aggregate base pavements that can be used to update the NCDOT’s life cycle cost analysis (LCCA) procedure, (2) to identify pavement sections that have both base types in order to recalibrate ME Design for North Carolina conditions, and (3) to develop guidelines for the recalibration of ME Design and demonstrate the data collection process using new paving projects.  

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