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

Construction quality acceptance performance-related specifications for chip seals

Adams, J., Castorena, C., & Kim, Y. R. (2019), JOURNAL OF TRAFFIC AND TRANSPORTATION ENGINEERING-ENGLISH EDITION, 6(4), 337–348. https://doi.org/10.1016/j.jtte.2019.05.003

Field measurements of emulsion application rates and pavement emulsion absorption in tack coats and chip seals

Malladi, H., & Castorena, C. (2019), CONSTRUCTION AND BUILDING MATERIALS, 218, 701–711. https://doi.org/10.1016/j.conbuildmat.2019.05.105

Impact of Crack Sealant on Pavement Skid Resistance

Fried, A., Malladi, H., & Castorena, C. (2019), TRANSPORTATION RESEARCH RECORD, 2673(7), 362–370. https://doi.org/10.1177/0361198119849590

In situ measurements of emulsion application rates

Rawls, M., & Castorena, C. (2019), INTERNATIONAL JOURNAL OF PAVEMENT ENGINEERING, 20(7), 811–819. https://doi.org/10.1080/10298436.2017.1347438

Evaluation of Chemical and Rheological Aging Indices to Track Oxidative Aging of Asphalt Mixtures

Rad, F. Y., Elwardany, M. D., Castorena, C., & Kim, Y. R. (2018), TRANSPORTATION RESEARCH RECORD, 2672(28), 349–358. https://doi.org/10.1177/0361198118784138

Low-Temperature Emulsion Performance-Graded Specification for Chip Seals

Castorena, C., Ilias, M., Adams, J., & Kim, Y. R. (2018), TRANSPORTATION RESEARCH RECORD, 2672(28), 266–276. https://doi.org/10.1177/0361198118790133

Low-Temperature Vacuum Drying Procedure for Rapid Asphalt Emulsion Residue Recovery

Malladi, H., Asnake, M., LaCroix, A., & Castorena, C. (2018), TRANSPORTATION RESEARCH RECORD, 2672(28), 256–265. https://doi.org/10.1177/0361198118791913

Performance-Graded Specifications for Asphalt Emulsions Used in Chip Seal Preservation Treatments

Adams, J., Ilias, M., Castorena, C., & Kim, Y. R. (2018), TRANSPORTATION RESEARCH RECORD, 2672(12), 20–31. https://doi.org/10.1177/0361198118770169

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. https://doi.org/10.1016/j.conbuildmat.2017.08.021

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. https://doi.org/10.3141/2612-05

View all publications via NC State Libraries

Grants

Screening of Asphalt Extenders and Recycling Agents

NC Department of Transportation(8/01/19 - 7/31/21)

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Screening of Asphalt Extenders and Recycling Agents

Sponsor: NC Department of Transportation

Start Date: 8/01/19

End Date: 7/31/21

Abstract

The use of asphalt mixtures containing high Recycled Binder Replacements (RBRs) is increasing. Recycled binders are oxidized and thus, harder and more susceptible to cracking than virgin binders. Consequently, the use of higher recycled content mixtures has prompted heightened interest in recycling agents and necessitated the use of asphalt extenders to produce softer virgin binder grades. Recycling agents include a wide-range of both softening agents and rejuvenators that are intended to restore the physical and chemical properties of aged asphalt binders. Petroleum-based extender products have been in existence for a long time (e.g., Re-refined Engine Oil Bottom (REOB)). Non-petroleum based products have been more recently introduced (e.g., bio-oils).

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Evolution of Pavement Friction and Macrotexture after Asphalt Overlay

NC Department of Transportation(8/01/19 - 7/31/21)

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Evolution of Pavement Friction and Macrotexture after Asphalt Overlay

Sponsor: NC Department of Transportation

Start Date: 8/01/19

End Date: 7/31/21

Abstract

Vehicle collisions and increases in collisions rates during wet conditions are one of the major safety concerns for the NCDOT. Wet collision rates increase because skid resistance reduces under wet conditions. The precise amount of loss is dependent on many factors, but the consensus among experts is that pavement friction and macrotexture are important factors that affect the skid resistance and changes in this resistance under wet conditions. Although the NCDOT actively addresses skid resistance issues as they are identified, a recent study involving a small subset of North Carolina roadways has suggested that wet crash rates may increase after pavements are overlaid. That study concluded that NCDOT needed to consider characterization of both friction and macrotexture as part of its pavement friction measurement and management plan. While the current studies have successfully identified the potential for issues in recently overlaid projects, they did not identify whether these effects are temporary, and if so, how long they may last. In addition, past studies have not been able to identify any specific causative effects that may increase or decrease the impact of overlays on skid resistance. Since the primary change after an overlay is placed is the driving surface, there is a need to better understand how the asphalt mixture composition may affect the overall skid resistance of the roadway under wet conditions.

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Evaluation of New Asphalt Concrete Job Mix Formula Specifications

NC Department of Transportation(8/01/19 - 7/31/20)

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Evaluation of New Asphalt Concrete Job Mix Formula Specifications

Sponsor: NC Department of Transportation

Start Date: 8/01/19

End Date: 7/31/20

Abstract

The North Carolina Department of Transportation (NCDOT) has recently modified the asphalt mixture design procedures in part, to increase the asphalt content and address observed cracking issues with asphalt mixtures. These changes have reduced the number of asphalt mixture types, changed compaction levels and the volumetric limits for some mixtures, and adjusted how recycled materials are considered. Given the complexity of the interactions between material parameters, the procedural changes do not guarantee that the resultant asphalt mixture designs have actually achieved the intended goal of improved durability.

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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 - 8/31/20)

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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: 8/31/20

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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