About

Cassie Castorena is a Lawrence A. Twisdale Jr. Distinguished Professor at NC State University within the Department of Civil, Construction and Environmental Engineering. Her professional role involves significant contributions to her field, although specific details about her research focus, background, and key contributions are not provided in the page text. As a distinguished faculty member, she is recognized for her expertise and leadership in her academic discipline.

Research topics

• Composite material
• Materials science
• Environmental science
• Engineering
• Civil engineering
• Forensic engineering
• Geotechnical engineering
• Structural engineering
• Meteorology
• Mathematics
• Waste management

Selected publications

• Variability in RAP and RAS stockpiles over time and their impacts on plant-produced asphalt mixtures

  Construction and Building Materials · 2026-02-25

  articleSenior author
  PublisherDOI

• Development of Precision Statements for the Asphalt Mixture Performance Tester Dynamic Modulus Test: A Framework for Small-Scale Specimens

  Transportation Research Record Journal of the Transportation Research Board · 2025-06-26

  article

  The dynamic modulus test is often adopted to characterize asphalt mixtures. The test results are used to compare asphalt mixtures’ resistance to deformation and serve as input for pavement performance predictions. American Association of State Highway and Transportation Officials (AASHTO) TP 132-19 provides guidelines on the test protocol required for small cylindrical specimens using the asphalt mixture pavement tester (AMPT), where significantly less material and testing time are needed compared with the standard for large cylindrical specimens (AASHTO T 378-17). Nonetheless, AASHTO TP 132-19 lacks repeatability and reproducibility limits for assessing the acceptability of test results. The study described in this paper presents the findings of an interlaboratory study (ILS) conducted to develop precision limits for AASHTO TP 132-19. Three mixtures and ten testing labs were involved in the experimental plan. Correlations were observed between dynamic modulus and both dynamic modulus coefficient of variation and phase angle standard deviation. Repeatability and reproducibility limits were proposed and defined as nonlinear functions of the dynamic modulus. The uncertainty in these nonlinear functional fits was incorporated into the proposed limits to help overcome limitations when assessing the test precision at various test determinations simultaneously. A novel mixture acceptance criterion was also proposed to help overcome the limitations from strict adherence to AASHTO T 378-17 while retaining the rigorousness of the statistics with marginal impact to pavement performance predictions.

  PublisherDOI

• Variability of Plant-Produced High Recycled Content Asphalt Mixtures Within a State

  Transportation Research Record Journal of the Transportation Research Board · 2025-04-02 · 1 citations

  articleSenior author

  The incorporation of recycled asphalt material (RAM) into asphalt mixtures is a widely adopted technique in the asphalt paving industry. U.S. state agencies limit the quantity of reclaimed asphalt pavement and recycled asphalt shingles in asphalt mixtures owing, in part, to concerns about variability in performance. The variability of RAM stockpile properties within a state can lead to inconsistencies in the properties and performance of asphalt mixtures. This study aims to characterize the properties of RAM materials within stockpiles over time and across multiple asphalt plants in North Carolina, U.S. It also evaluates the variability in performance of plant-produced high recycled content mixtures in the state and investigates the potential causes for this variability. Asphalt mixtures and their constituent materials were acquired and characterized from four asphalt plants on two different dates. The results show that, while RAM properties were generally consistent within stockpiles over time, significant variations in binder properties and asphalt content were found across different plants within the state. The majority of the mixtures evaluated showed consistent rutting and cracking performance. Variability in cracking performance across plants could be linked to the properties of the recycled and virgin binders. The differences in cracking and rutting performance between the first and second samples acquired from a given plant closely mirrored asphalt content differences.

  PublisherDOI

• Using Color Measurements to Assess Reclaimed Asphalt Pavement Degree of Activity

  Transportation Research Record Journal of the Transportation Research Board · 2025-09-08

  articleSenior author

  High reclaimed asphalt pavement (RAP) content mixtures pose a challenge because of uncertainty about the activity level of RAP binder during production. This activity level, termed degree of activity (DoA), influences the integration of RAP binder into the virgin binder matrix of asphalt mixtures. This study proposes a practical method for measuring DoA using light intensity (LI) measurements obtained from the asphalt compatibility tester (ACT). As darker colors reflect less light, it is hypothesized that LI decreases as the activation level of RAP increases. Thus, LI can provide a quantitative measure associated with DoA for RAP samples. Furthermore, this study compares DoA measurements obtained using the ACT with those obtained using a method associating DoA with indirect tensile strength (ITS) of 100 percent RAP specimens. The two methods showed similar trends, but their measurements occasionally diverged. Both methods demonstrated an increase in DoA as temperatures rose from 100°C to 155°C, with DoA values exceeding 70% at standard production temperatures (140°C–155°C) for hot asphalt mixtures. The ACT-based DoA measurement approach holds promise for improving material selection and the design of recycled asphalt mixtures. However, further validation with a broader range of RAP sources is required to confirm its reliability and applicability across varying material sources.

  PublisherDOI

• Using Color Measurements to Quantify Aggregate and Asphalt Emulsion Compatibility

  Transportation Research Record Journal of the Transportation Research Board · 2024-05-04

  articleSenior authorCorresponding

  The compatibility of asphalt emulsion and aggregate plays a significant role in the aggregate retention performance of chip seals. There are several, similar standardized test methods available for assessing the compatibility of emulsion–aggregate blends, including AASHTO T 59, ASTM D244, and North Carolina Department of Transportation (NCDOT) A-24. In all methods, a sample of aggregate and emulsion is mixed and rinsed. Subsequently, the compatibility of the rinsed sample is reported as “good,”“fair,” or “poor” based on visual inspection of asphalt coating the aggregate surface area. These visual inferences are subjective, making them susceptible to potential operator bias. The aim of this study is to develop an objective means to quantify emulsion–aggregate compatibility by using the Asphalt Compatibility Tester to obtain color-based measures in lieu of the visual assessment procedures. Multiple aggregate sources (granite, limestone, and lightweight), emulsion types (CRS-2L, CRS-2, and SS-1h), and sources were evaluated. In total, 25 emulsion–aggregate blends were analyzed. The results were used to establish color index thresholds to capture good- versus fair- or poor-performance emulsions. Additionally, chip seal samples from five construction projects were subjected to the Vialit test to measure aggregate retention performance. The Vialit test results were compared with the compatibility test results as a preliminary evaluation of the color-based criteria proposed here. The results indicated that the NCDOT A-24 procedure coupled with color measurements is effective at capturing the compatibility of emulsion–aggregate blends, providing a potential means to remove the subjectivity of the current visual rating procedures.

  PublisherDOI

• Availability adjusted mix design method as a tool to mitigate the adverse effects of RAP on the performance of asphalt mixtures

  Construction and Building Materials · 2024-03-18 · 8 citations

  articleSenior author
  PublisherDOI

• Understanding recycling agent modification mechanisms through rheological and compositional impacts

  International Journal of Pavement Engineering · 2024-12-26 · 2 citations

  articleSenior authorCorresponding
  PublisherDOI

• A framework to identify fatigue failure of asphalt binders under multiple aging levels using linear amplitude and time sweep testing

  International Journal of Pavement Engineering · 2024-06-19 · 4 citations

  article

  The identification of fatigue failure can significantly affect the determination and prediction of fatigue life for a given asphalt binder. In this work, different approaches for identifying the fatigue failure on linear amplitude sweep (LAS) and time sweep (TS) are compared, especially for highly-aged asphalt binders. The candidate methods include traditional 50% or 80% reduction in pseudo-stiffness parameter (denoted as C0.5 and C0.2), peak stored pseudo-strain energy (PSE), peak C × N and peak phase angle. For asphalt binder at multiple aging levels, peak C × N is found to be effective in defining fatigue failure of TS testing. Meanwhile, peak stored PSE is suitable as the failure definition of LAS because it can capture the benefit of polymer modification and has a high accuracy for fatigue life prediction. Nf in strain-control TS test determined by different failure definitions shows that aging can increase the fatigue resistance at early-aged levels and then decrease the fatigue resistance at highly-aged levels. In general, the selected failure definitions have little influence on the trend of Nf with age levels. The purpose of this work is to select the logical failure definitions of asphalt binder under multiple aging levels.

  PublisherDOI

• Mechanical Properties and Performance of Mixtures Containing a High Level of Recycled Materials That Are Designed Using Alternative Approaches

  Transportation Research Record Journal of the Transportation Research Board · 2024-04-13 · 1 citations

  articleSenior author

  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 FlexPAVE TM 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.

  PublisherDOI

• Validation of a sieve analysis procedure to quantify reclaimed asphalt pavement (RAP) binder availability

  International Journal of Pavement Engineering · 2024-11-13 · 3 citations

  articleSenior author
  PublisherDOI

Recent grants

• Renewable Paving Binders from Top-lit Updraft Kilning of Biomass

  NSF · $375k · 2015–2021

Frequent coauthors

• B. Shane Underwood

  North Carolina State University

  29 shared

• Y. Richard Kim

  16 shared

• Farhad Yousefi Rad

  Anton Paar (United States)

  16 shared

• Saqib Gulzar

  North Carolina State University

  13 shared

• Sonja Pape

  North Carolina State University

  13 shared

• Kang-Jin Lee

  Federal Highway Administration

  12 shared

• Andrew Fried

  North Carolina State University

  11 shared

• Michael Elwardany

  11 shared

Labs

• Civil, Construction and Environmental EngineeringPI

Education

• Ph.D., Environmental Engineering

  University of California, Berkeley

  2005

• M.S., Environmental Engineering

  University of California, Berkeley

  2001

• B.S., Environmental Engineering

  University of California, Berkeley

  1999

Awards & honors

• Alumni Distinguished Undergraduate Professor Award (2024)
• Outstanding Teacher Award (2017)
• Fred Burggraf Outstanding Paper Award (2024)
• Transportation Research Board Standing Committee on Binders…
• ASCE Transportation and Development Institute Outstanding Yo…