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

Improved interpretation of asphalt binder parallel plate dynamic shear rheometer fatigue tests

Safaei, F., & Castorena, C. (2020), INTERNATIONAL JOURNAL OF PAVEMENT ENGINEERING, 21(1), 74–87. https://doi.org/10.1080/10298436.2018.1438611

Low-temperature performance grade characterisation of asphalt binder using the dynamic shear rheometer

Underwood, B. S., & Castorena, C. (2020), INTERNATIONAL JOURNAL OF PAVEMENT ENGINEERING. https://doi.org/10.1080/10298436.2020.1774766

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

The effect of laboratory compaction method on the resilient behaviour and fabric of aggregate base course materials

Bozorgi, A., Fried, A., Montoya, B. M., & Castorena, C. (2019), Road Materials and Pavement Design, 2, 1–13. https://doi.org/10.1080/14680629.2019.1580606

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

View all publications via NC State Libraries

Grants

Evaluating Recycling Agents’ Acceptance for Virginia: Test Protocols and Performance-Based Threshold Criteria

US Dept. of Transportation (DOT)(7/01/20 - 1/31/23)

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Evaluating Recycling Agents’ Acceptance for Virginia: Test Protocols and Performance-Based Threshold Criteria

Sponsor: US Dept. of Transportation (DOT)

Start Date: 7/01/20

End Date: 1/31/23

Abstract

In 2007, the Virginia Department of Transportation (VDOT) introduced specifications to allow higher percentages of reclaimed asphalt pavement (RAP) (i.e., up to 30%) in hot-mix asphalt (HMA) surface mixtures without adjustment of the virgin binder grade. The increased use of RAP was expected to result in a lower cost of produced asphalt mixtures given the continuous rising cost of oil and thus asphalt binders and fuel needed to produce asphalt pavements. By 2013, VDOT had begun to consider the feasibility of allowing the use of surface mixtures containing up to 45% of RAP material. Several trial sections were constructed containing mixtures with 20%, 30%, 40%, and 45% RAP for evaluation (Nair et al., 2019). In general, those trials found that mixtures containing up to 45% RAP could be designed, produced, and constructed if proper procedures are followed. In 2019, the research team at Virginia Transportation Research Council (VTRC) initiated another study to evaluate field trials of high RAP asphalt mixtures (i.e., more than 40%) designed following the Balanced Mix Design (BMD) special provision for VDOT’s surface mixtures. The primary concern with such mixtures has been that the use of high percentage of RAP will overly stiffen mixtures; making them more brittle and prone to premature cracking. The use of high percentage of RAP can lead to numerous construction and performance issues including, but not limited to, compactibility and workability in cool weather, low-temperature cracking with accumulation of thermally induced stresses, fatigue cracking and micro damage accumulation leading to crack initiation and propagation with repeated loading, reflection cracking with repeated loading and daily / seasonal thermal stresses, and raveling with subsequent aging or moisture damage. The challenges arising from the use of high RAP content mixtures can be addressed through the use of softer binders or additives such as recycling agents (RAs). These additives were utilized in HMA in the early period of widespread recycling in the 1970s and 1980s for the purpose of realizing three types of benefits: environmental, economic, and engineering. The use of RAs holds promise as long as there is a proper understanding of how effectively they restore binder rheology and how that effectiveness evolves with aging of mixtures in the laboratory, making them proper additives to be incorporated in mixtures to be placed in field. Hence, there is a need for an engineered framework to evaluate RAs in terms of their stiffness and cracking resistance when incorporated into the binder blends of corresponding mixtures. Currently, there are no unique and / or detailed handy guides or specifications that outline a framework to evaluate acceptability of RAs in the state of Virginia. Therefore, this study aims to identify and / or develop a testing protocol to evaluate the effectiveness of RAs in alleviating the brittleness of high RAP asphalt mixtures. In addition, a performance-based parameter(s) with its threshold limits / criteria will be identified or developed to accept or reject a certain product (i.e., recycling agents). Both objectives will facilitate responsible use of innovative materials as part of Virginia’s Balanced Mix Design (BMD) initiative. In this study, NCSU researchers will conduct experiments on asphalt binder, asphalt from reclaimed asphalt pavement (RAP), rejuvenator agents, mortars, and asphalt mixture.

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Ruggedness and Interlaboratory Studies for Asphalt Mixture Performance Tester (AMPT) Small Scale Dynamic Modulus

Federal Highway Administration (FHWA)(3/11/20 - 8/23/22)

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Ruggedness and Interlaboratory Studies for Asphalt Mixture Performance Tester (AMPT) Small Scale Dynamic Modulus

Sponsor: Federal Highway Administration (FHWA)

Start Date: 3/11/20

End Date: 8/23/22

Abstract

In this research study, NCSU will design, conduct, and provide recommendations relating to a two-phase ruggedness and interlaboratory study on a test method that has been identified as critical to asphalt pavement performance and design practice. AASHTO TP 132 (2019) Standard Method of Test for Determining the Dynamic Modulus for Asphalt Mixtures Using Small Specimens in the Asphalt Mixture Performance Tester (AMPT) has been developed, refined, and recently published as an AASHTO provisional standard; a statistically sound refinement procedure is needed to facilitate widespread adoption and implementation. Not only can this standard be used to obtain inputs to the AASHTO PavementME pavement structural analysis software, the standard is being used in ongoing FHWA efforts as part of a performance-related specification framework which seeks to increase pavement life through fundamental testing and predictive relationships. AASHTO TP 132 is of interest because of its fundamental nature, determination via the AMPT standardized equipment, and its ability to model and predict material performance over a wide range of loading and climate conditions a pavement may experience; resulting in better performing, safe, quiet, durable, long lasting asphalt roadways. Additionally, a draft practice for preparing small-scale specimens has been developed and published as AASHTO PP 99 (2019) Standard Method of Practice for Preparation of Small Cylindrical Performance Test Specimens Using the Superpave Gyratory Compactor (SGC) and Field Cores. This draft practice is of significant interest to the asphalt materials community due to anticipated materials, time, and cost savings associated with preparing and evaluating smaller performance test. NCSU will carry out the following tasks. Task 1 – Develop final research plans and project schedule – The proposed plan will be revised based on feedback from the FHWA. Task 2 – Kickoff meeting – NCSU will meet with the project panel to review the statement of work and work plans. Task 3 – Perform work plan and document efforts – NCSU will carry out the approved work plan by following the appropriate ASTM standard test methods to develop a rugged test method. Task 4 – Ruggedness study presentations and webinar – NCSU will present the findings to targeted stakeholders. Task 5 – Publication ready final deliverables – the AASHTO standards will be revised into a final form. Task 6 – Revise work ILS work plan – NCSU will revise the original work plan from Task 1 based on findings from Tasks 3-5 for conducting the ILS study. Task 7 – Perform work plan and document efforts – NCSU will coordinate the ILS according to the approved work plan. This will include identifying participants, sending materials, and analyzing their results statistically. Task 8 – ILS study presentation and webinar – NCSU will present their findings to targeted stakeholders. Task 9 – Publication ready final deliverables – the AASHTO standards revised in Task 5 will be modified to include repeatability and reproducibility statements.

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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 - 1/31/21)

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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: 1/31/21

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 - 1/31/21)

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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: 1/31/21

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 - 1/31/21)

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Improving the Design of RAP and RAS Mixtures

Sponsor: NC Department of Transportation

Start Date: 8/01/18

End Date: 1/31/21

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 - 12/26/20)

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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: 12/26/20

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 - 12/31/20)

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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: 12/31/20

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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