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INSTRUCTORS:
Wynand Steyn
Regis Carvalho
Mohamad Yaman Fares
Purpose and Background
These presentations were recorded at the International Airfield & Highway Pavements Conference 2025.
Comparative Assessment of Gyratory and Roller Slab Compaction Methods on HMA Rutting Resistance (22 minutes)
This presentation explores the differences in rutting resistance of hot mix asphalt (HMA) based on two widely used laboratory compaction methods: gyratory compaction and roller slab compaction. Using standard South African dense-graded asphalt mixes, the study evaluated the resulting rutting performance through repeated simple shear and uniaxial tests. The presenter emphasized the influence of laboratory compaction techniques on test results and the importance of matching laboratory procedures with field expectations. Notably, the gyratory compactor yielded consistently lower permanent strains compared to the roller slab compactor. The study warns against making direct numerical translations across contexts but underlines the need to understand how equipment and procedures affect outcomes. The work is part of a larger national effort to better link lab results with field performance through a reference laboratory framework.
The Use of Balanced Mix Design Process With High Polymer Modified Asphalt at a Brazilian Airport (28 minutes)
This case study details a balanced mix design (BMD) approach implemented at a Brazilian airport to resolve premature pavement distresses observed in a recently rehabilitated runway. The project used highly modified asphalt (HiMA) with SBS polymers to develop both bottom and surface mixes tailored for cracking and rutting resistance, respectively. The performance-based approach incorporated flow number and fatigue factor metrics to validate mix designs. Additionally, field test sections were constructed to evaluate friction and other operational concerns before full deployment. The BMD approach resulted in significant improvements in predicted performance and reduced cracking potential, as confirmed by FlexPave simulations. This project exemplifies the integration of structural design and mix optimization in aviation pavement applications.
Impact of Unbound Layer Mineralogy on the Long-Term Performance and Cost-Effectiveness of Pavements (14 minutes)
This presentation evaluates how the mineralogical composition of unbound aggregate layers affects the mechanical performance and long-term durability of flexible pavements. Using controlled laboratory testing and mechanistic-empirical pavement design, the study compared four aggregate types (quartzite, dolomite, granite, and limestone) with identical gradation but varying mineral content. The dolomite-based aggregates demonstrated superior stiffness (resilient modulus), resulting in longer pavement service life. The findings highlight that current selection practices based solely on gradation and location may overlook important mineralogical effects. The presentation recommends incorporating mineralogical considerations or more robust resilient modulus testing into pavement design procedures to enhance cost-effectiveness and longevity.
Benefits and Learning Outcomes
Upon completion of this course, you will be able to:
- Describe the comparative impact of gyratory and roller slab compaction methods on HMA rutting resistance.
- Explain why laboratory compaction methods must align with field conditions to ensure accurate performance predictions.
- Discuss how balanced mix design with highly modified asphalt can improve fatigue and rutting performance in critical infrastructure.
- Identify the performance testing criteria used to validate BMD for airport pavement rehabilitation.
- Explain how the mineralogy of unbound aggregates influences resilient modulus and pavement service life.
- List limitations of current aggregate selection practices and propose strategies to incorporate mineralogical effects in pavement design.
Assessment of Learning Outcomes
Students' achievement of the learning outcomes will be assessed via a short post-test assessment (true-false, multiple choice, and/or fill in the blank questions).
Who Should Attend?
- Transportation Engineers
- Transportation Professionals
- Materials engineers
- Consultants & Contractors
- Academics & Researchers
- Young Professionals & Students
How to Earn Your CEUs/PDHs and Receive Your Certificate of Completion
To receive your certificate of completion, you will need to complete a short post-test and receive a passing score of 70% or higher within 1 year of purchasing the course.
How do I convert CEUs to PDHs?
1.0 CEU = 10 PDHs [Example: 0.1 CEU = 1 PDH]