Purpose: NCHRP D-18 outlines a research agenda to develop performance-based acceptance and incentive tests for asphalt emulsion treatments, including chip seals, micro surfacing, slurry seals, tack coats, and cold recycling. The objective is to identify laboratory and field tests that predict treatment performance and service life more reliably than current material- and design-based specifications alone.

Why it matters: State transportation agencies rely heavily on material specifications and design guidance, but they lack standardized performance thresholds tied to field outcomes. As a result, agencies have limited ability to implement performance-based contracting, set acceptance or incentive criteria, or compare results consistently across suppliers and regions. Validated tests would improve construction quality, reduce early failures, and support more predictable preservation performance.

Key findings: Although AASHTO and related committees maintain extensive material and design standards for emulsions, no unified treatment-level performance test framework exists. Priority attributes include early-life cohesion and curing, durability, moisture susceptibility, rutting resistance, cracking resistance, and long-term aging. The problem statement emphasizes that post-break binder properties and treatment-level testing are essential to connect emulsion chemistry with field performance.

Research gaps: D-18 identifies three main barriers to performance-based acceptance: no consensus test suite for each treatment type, limited standardized protocols for residue recovery and curing simulation, and no broadly accepted thresholds or incentive metrics linked to field performance. In short, material characterization alone is not sufficient without evidence of in-service behavior.
Ongoing national work. Efforts to close these gaps are underway through the AASHTO Emulsion Task Force, related NCHRP studies, and DOT pilot programs. Current work focuses on post-break binder characterization, treatment-level test methods, and validation of candidate procedures such as Cantabro loss, wet track abrasion, Hamburg wheel tracking on residues, and residue rheology. Together, these efforts align with the D-18 roadmap, although D-18 itself has not yet advanced as a funded NCHRP project.

Implications: If the recommended research is completed and validated, agencies could adopt performance-based acceptance and incentive programs for emulsion treatments with greater confidence. Standardized tests would support objective supplier comparisons, encourage innovation in formulation and construction, and improve consistency in preservation outcomes nationwide.
Primary source: NCHRP Problem Statement D-18, Performance-Based Tests for Asphalt Emulsion Treatments (FY2024), supplemented by AASHTO Emulsion Task Force activities, updates to emulsion test methods, and related NCHRP treatment-level testing projects.

Establishing Particle Size Recommendations for Cationic Asphalt Emulsions

Current asphalt emulsion specifications largely rely on testing methods that haven’t changed much since the 1930s. The current tests tell you whether an emulsion passes the established specification, not whether it will perform. Newer tests like particle size analysis (PSA) have been studied but not implemented for use in specifications.

Researchers tested two cationic slow-setting emulsions (CSS-1 and CSS-1H) over six months using both standard physical property tests (residue, oversize particles, viscosity, and particle size) and two cold mix performance tests: indirect tensile strength (IDT) and direct shear strength (DST) on RAP specimens. Both emulsions cleared conventional spec requirements the whole time. But particle size picked up something viscosity and residue tests missed: the CSS-1H, with a median droplet diameter about 3 microns larger, consistently produced higher strength in both tests. The emulsions also remain stable for over six months with minimal particle size drift, which matters because PSA needs to be implementable without worrying about rapid property change during storage.

The output of the study is a proposed set of particle size limits for CSS emulsions: maximum median (d50) of 6.0 microns, with limits on d10, d90, and span to constrain the full distribution. Broader validation is still needed, but this gives performance-based specification work a quantified starting point for PSA as a routine quality control tool — one that can link what’s in the tank to what happens on the road. This is one of many research initiatives currently in the industry striving to better understand field performance of emulsions in practice before they leave our facilities.

Turben, T., Diaz-Romero, P., & Braham, A. (2025). Establishing particle size recommendations for cationic asphalt emulsions. Construction Materials, 5(2), 26. https://doi.org/10.3390/constrmater5020026

Study of High-Temperature Rheological Properties of Emulsified Asphalt Residues

This paper looks at how emulsification and aging influence the high-temperature performance of asphalt residues, which ultimately control pavement behavior. The authors utilize dynamic shear rheometer testing (temperature sweeps and MSCR) and fluorescence microscopy, to compare base asphalt, SBS-modified asphalt, and their emulsified residues. The key finding is that emulsification does not affect all binders equally: base asphalt sees modest improvements in stiffness and deformation resistance, while SBS-modified asphalt can be negatively impacted due to mechanical shear during emulsification that disrupts its internal polymer network. 

Rheological testing shows that temperature reduces stiffness in all materials, but polymer modification significantly enhances elastic recovery and resistance to permanent deformation. Among the systems studied, SBS/SBR modified emulsified asphalt provides the best overall high-temperature performance. Aging increases stiffness but reduces elasticity, with base asphalt losing most of its recovery ability. Modified binders retain better performance and show improved resistance to aging effects. 

Microscopic analysis explains these trends: emulsification and aging breaks down the continuous SBS network into dispersed structures, leading to reduced performance in SBS-modified residues. The study concludes that while emulsification can be beneficial, it can also degrade polymer-modified systems unless formulation and processing are carefully controlled, and that composite modification (SBS/SBR) is the most robust approach for maintaining high-temperature performance.

Wang, H.; Li, C.; Xu, G.; Zhou, Y.; Wang, R. Study of High-Temperature Rheological Properties of Emulsified Asphalt Residues. Coatings 2024, 14, 522. https://doi.org/10.3390/coatings14050522

Research on the Preparation Process and Performance Improvement of a New Type of Asphalt Emulsion Cold Patch Material

This study focuses on developing an improved asphalt emulsion cold patch mixture that addresses common limitations of existing materials, particularly poor storage stability and insufficient early strength for effective pothole repair applications. 

Cold patch materials are widely used for maintenance operations due to their ease of application and ability to be placed without heating; however, conventional formulations often exhibit limited durability and delayed strength gain, which reduces their effectiveness in field conditions. To address these issues, the study develops a modified asphalt emulsion mixture using an AC-13 gradation and evaluates the impact of key variables such as asphalt emulsion dosage, water content, and cement addition on mix performance. 

The results demonstrate that optimizing mixture proportions is critical to achieving both workability and performance. The study identifies an optimal formulation in which the addition of a small amount of composite Portland cement significantly improves early strength development without compromising handling characteristics. Specifically, incorporating approximately 3% cement substantially increases short-term strength while maintaining adequate working time for placement and compaction. This balance between early strength and workability is essential for field applications where rapid reopening to traffic is required. 

In addition to cement, the use of chemical additives such as demulsifiers and early-strength water-reducing agents is shown to further enhance performance. These additives accelerate water loss after compaction, improving curing characteristics and increasing early strength gain. The study reports that modified systems achieve significantly higher water loss rates within the first few days, which contributes directly to strength development and improved material stability. 

Comprehensive performance testing confirms that the improved cold patch material exhibits enhanced mechanical properties compared to conventional and SBS-modified emulsified asphalt mixtures. Evaluated properties include Marshall stability, water stability, high-temperature performance, and workability. The results indicate that the optimized formulation provides better overall pavement performance and is more suitable for practical construction requirements, particularly in maintenance scenarios requiring rapid and durable repairs. 

Overall, the study concludes that cold patch performance can be significantly improved through a combination of optimized mix design, strategic use of cementitious materials, and chemical modification of the emulsified asphalt system. These improvements enable the development of a semi-permanent repair material that offers both extended storage capability and rapid strength gain, providing a practical and effective solution for pothole repair and maintenance operations.

Ouyang, J., Zhao, S., Cao, H., & Jiang, J. (2025). Research on the preparation process and performance improvement of a new type of asphalt emulsion cold patch material. Journal of Materials in Civil Engineering, 37(6), 04025132. https://doi.org/10.1061/JMCEE7.MTENG-19939

Written By: Brenna Collins, Aidan Ketterer, and Wesley Geiger

Spray-On Rejuvenators at MnROAD

NCAT’s “Spray-On Rejuvenators at MnROAD” article summarizes a field study designed to determine how well spray-applied rejuvenators perform as pavement preservation treatments over time. In the study, MnROAD constructed two nearly identical asphalt sections in 2021 using the same dense-graded mix with 20% RAP, but with different binders: one unmodified and one polymer-modified. Then, they applied 12 different spray-on rejuvenators across test cells for comparison against untreated controls.  Researchers evaluated the sections over 24 months using laboratory binder testing and field measurements of friction, texture, and permeability to assess both the chemical and rheological effects of the products and their practical impact on pavement surface performance and safety.

The article’s main takeaway is that spray-on rejuvenators can be effective, but their success is product-specific and depends more on formulation, compatibility, and the amount of residual oil mass retained in the pavement than on whether the product is bio-based or petroleum-based.  The study also found that many products caused an initial reduction in friction before recovering as the treatment cured, which means agencies should plan for short-term friction management and use pilot sections when needed.  Overall, the article recommends that agencies base specifications on retained residual oil mass, consider pavement condition and binder type when selecting products, and evaluate both field performance and binder property changes over time before adopting spray-on rejuvenators as a routine preservation strategy.

National Center for Asphalt Technology. (2025). Spray-on rejuvenators at MnROAD. Auburn University Samuel Ginn College of Engineering. https://www.eng.auburn.edu/research/centers/ncat/newsroom/2025-fall/spray-on-rejuventators-mnroad.html

Innovative geopolymer‑based cold asphalt emulsion mixture as eco‑friendly material

The study investigates how to improve the performance of cold asphalt emulsion mixtures (CAEM), which are valued for reduced energy consumption and emissions but often criticized for inferior mechanical performance compared to hot‑mix asphalt. Researchers explored replacing traditional high‑cost additives like ordinary Portland cement with geopolymer forming industrial byproducts, specifically waste alkaline Ca(OH)₂ solution, ground granulated blast‑furnace slag (GGBFS), and calcium carbide residue (CCR). These materials were used to create an innovative geopolymer based cold asphalt emulsion mixture (GCAE). The authors utilized a standard CSS emulsion. The waste alkaline Ca(OH)₂ solution was particularly effective, accelerating early hydration and promoting rapid early‑age strength development, as confirmed by scanning electron microscopy analyses.

Experimental results demonstrated that GCAE exhibits significantly enhanced strength, durability, and performance under moisture and temperature stresses compared to conventional approaches. By leveraging industrial byproducts instead of conventional cementitious additives, the approach the authors outline offers both economic and environmental benefits, aligning with sustainable infrastructure goals. The study concludes that geopolymer modifications represent a promising pathway for improving CAEM performance while simultaneously reducing reliance on energy intensive materials.

Dulaimi, A., Al Busaltan, S., Othuman Mydin, M. A., Lu, D., Özkılıç, Y. O., Putra Jaya, R., & Ameen, A. (2023). Innovative geopolymer‑based cold asphalt emulsion mixture as eco‑friendly material. Scientific Reports, Nature Publishing Group. https://www.nature.com/articles/s41598-023-44630-5.pdf

Executive Summary: U.S. Patent 3,162,101

Methods for Improvement of Asphalts and Oil Emulsions Useful Therein
Fritz S. Rostler (1964)

This patent establishes the scientific basis for modern asphalt rejuvenation by demonstrating that asphalt durability is controlled by chemical composition balance rather than penetration or viscosity alone. The invention focuses on managing the internal fractions of asphalt—particularly maltenes and asphaltenes—to restore or improve performance in both weathered and unweathered pavements.

Asphalt is shown to consist of asphaltenes and maltenes, the latter comprising nitrogen bases, first acidaffins, second acidaffins, and paraffins. Rostler identifies a critical durability parameter, R = (Nitrogen Bases + First Acidaffins) / (Paraffins + Second Acidaffins). Weathering drives this ratio outside its optimal range by converting maltenes into asphaltenes, resulting in brittleness, loss of adhesion, and increased abrasion.

The invention teaches that asphalt performance is maximized when the R-value is maintained approximately between 0.4 and 1.5, with paraffins generally below about 40 percent. Asphalt outside this range can be chemically rebalanced by adding selected petroleum fractions rich in maltenes, rather than simple softening oils. Importantly, the added oils must be high-boiling, substantially free of asphaltenes and light volatile fractions, which were shown to reduce durability.

A critical advancement of the patent is the use of cationic or mixed cationic–nonionic emulsions to deliver these corrective maltenes into asphalt pavements. These emulsions preferentially wet asphalt instead of aggregate, penetrate deeply into the pavement structure, and avoid surface glazing, runoff, or stripping. This enables effective ‘sealing in depth’ and restoration of asphalt chemistry rather than superficial treatment.

Extensive laboratory testing (Shot Abrasion and Pellet Tests) and field trials demonstrate that chemically rebalanced asphalt exhibits reduced abrasion loss, improved bonding to aggregate, lower permeability to water, and often greater durability than the original asphalt. The methods apply broadly to preventive maintenance, pavement rejuvenation, in-place recycling, and reconstruction. Overall, the patent defines a durable, chemistry-driven approach to extending pavement life and underpins modern maltene-based rejuvenation technologies used in practice today.

Rostler, F. S. (1964). Methods for improvement of asphalts and oil emulsions useful therein (U.S. Patent No. 3,162,101). United States Patent and Trademark Office.

Asphalt Rejuvenators – Fact or Fable

Robert E. Boyer, PhD, PE, Asphalt Institute

This paper examines whether asphalt rejuvenators are a legitimate pavement preservation technology or merely anecdotal treatments. Dr. Robert Boyer evaluates rejuvenators from a materials science and pavement engineering perspective, establishing performance criteria, reviewing available research, and identifying appropriate uses and limitations.

Asphalt binder is not a single chemical material, but a system of fractions consisting primarily of asphaltenes and maltenes. Asphaltenes provide stiffness and strength, while maltenes—composed of nitrogen bases and resinous and oily fractions—provide flexibility, adhesion, and durability. Asphalt aging occurs when oxidation and weathering convert maltenes into asphaltenes, reducing the maltene‑to‑asphaltene ratio. This shift causes asphalt to become stiff, brittle, and prone to cracking and raveling.

A true asphalt rejuvenator must therefore do more than soften the surface. According to Boyer, an effective rejuvenator must be chemically compatible with asphalt binder, capable of penetrating the pavement surface, and able to restore the maltene balance by re‑peptizing existing asphaltenes. Materials that simply coat the surface or lubricate the pavement do not meet this definition and may provide only short‑term cosmetic improvement.

The report emphasizes that rejuvenator performance must be evaluated using engineering-based testing, not appearance alone. Recommended evaluation methods include binder extraction and recovery, viscosity and penetration testing, assessment of depth of penetration, and observation of long‑term field performance such as cracking, raveling, and oxidation rate. Visual darkening or short‑term softness is not sufficient evidence of rejuvenation.

Based on laboratory studies and field applications reviewed, Boyer concludes that properly formulated and properly applied rejuvenators can be effective. When used on pavements that are structurally sound and treated early in the aging process, rejuvenators can slow oxidation, restore some flexibility, and extend pavement service life by several years. This life extension can significantly reduce life‑cycle maintenance costs.

However, the paper also highlights important limitations. Rejuvenators are preventive maintenance treatments, not structural repairs. Their effectiveness depends strongly on pavement condition, traffic level, and application rate. Over‑application or use on heavily trafficked or structurally distressed pavements can result in instability, bleeding, or temporary loss of friction. Careful project selection and controlled application are essential.

Key Conclusions

• Asphalt rejuvenators are fact, not fable, when grounded in asphalt chemistry.
• Effectiveness depends on restoring maltene–asphaltene balance, not surface sealing.
• Rejuvenators should be applied early, on sound pavements, as part of a preventive maintenance program.
• Engineering evaluation—not appearance—must guide acceptance.

Boyer, R. E. (2000). Asphalt rejuvenators: Fact or fable. Asphalt Institute. Paper presented at the Transportation Systems 2000 (TS2K) Workshop, San Antonio, TX.

LEAP Program Tour: Ergon Asphalt & Emulsions

During the month of February, the 2026-2027 LEAP class had the opportunity to visit Ergon Asphalt & Emulsions in Austin, Texas for an informative tour of the facility and to learn more about the production of asphalt emulsions used in roadway construction and pavement preservation.

The visit began with a comprehensive safety orientation followed by an overview of the facility’s operations. The Ergon team introduced participants to the asphalt emulsion manufacturing process and explained how asphalt emulsions are produced by blending asphalt, water, and specialized additives to create materials used in a variety of pavement maintenance treatments.

During the presentation, participants learned about the different types of asphalt products produced and distributed by Ergon, including conventional asphalt binders, polymer-modified asphalt, and specialty pavement preservation products. These materials are commonly used in road construction and maintenance projects such as chip seals, slurry seals, tack coats, and other surface treatments designed to extend the life of roadways.

Following the presentation, the group toured the facility grounds, where participants were able to observe key areas of the plant including storage terminals, mixing equipment, and loading stations used to transport materials to various projects across the region. The tour provided valuable insight into the coordination, safety practices, and technical expertise required to operate an asphalt emulsion plant.

The Austin facility plays an important role in supporting roadway maintenance and infrastructure projects throughout Texas and surrounding regions. The plant is equipped with specialized blending systems, storage tanks, and loading facilities that allow the team to safely manufacture and distribute asphalt emulsion products to contractors and transportation agencies.

The LEAP participants appreciated the opportunity to learn directly from industry professionals and gain a deeper understanding of the processes and technology used in modern pavement preservation. Experiences like this allow participants to connect classroom knowledge with real-world applications that help maintain safe and durable road networks.

The Excellence in Manufacturing Award is presented to qualifying plants that meet or exceed AEMA requirements demonstrating best practices in all areas of manufacturing. This year, the Excellence in Manufacturing Award at the Bronze level was awarded to Ergon Asphalt & Emulsions Newport News and Dumfries Plant; Jebro Inc’s Sioux City Plant, and Western’s Asphalt Products Bruderheim Plant. Additionally, there were 10 plants who renewed at this level.

After five years at the bronze level, plants can apply for the Excellence in Manufacturing Award Silver Level. This year, there were 23 plants that were recognized. Asphalt Materials had a total of six plants receiving this award which include their Columbus Plant, Oregon Plant, Warsaw Plant and HG Meigs Eau Claire Plant, Abbotsford Plant and Portage Plant. Associated Asphalt’s two plants included Roanoke and Tampa Emulsions. Ergon Asphalt & Emulsions had five plants including Catoosa, Chandler, El Dorado, Pleasanton, Roswell plants and Ergon Asfaltos Mexico Torreon Plant. McAsphalt Limited Industries had four plants receive this award this year which include their Ottawa, Acheson, Brampton, and Thunder Bay plants. Russell Standard had their Akron 205 and Chambersburg 415 Plants. Lastly, VSS Emultech’s Bakersfield Plant. Additionally, there were 35 plants that renewed at this level.

The AEMA Past President’s Award for Emulsion Excellence recognizes a standout project completed in the past year that demonstrates exceptional use of asphalt emulsions. Each year, the award is presented to the agency, contractor, and emulsion manufacturer whose work best exemplifies innovation, quality application, and long-term value in pavement preservation. For 2026, the AEMA Past President’s Award for Emulsion Excellence goes to the Green Oaks Subdivision Project. This year’s winning project, led by the City of Starkville Engineering Department in partnership with TL Wallace and Ergon Asphalt & Emulsions, showcases a data-driven and community-focused approach to pavement preservation. The team implemented a combination of treatments – including crack sealing, rejuvenating scrub seal, highly modified micro surfacing, and cape seal – to address widespread cracking and extend pavement life across multiple neighborhood streets. These strategies delivered long-lasting durability, improved safety, and significant cost savings compared to traditional mill-and-fill methods.

The Green Oaks project stands as a model of smart infrastructure management, demonstrating the impact of applying the right treatments at the right time while keeping residents informed every step of the way.

In just a few short weeks, the 2026 AEMA‑ARRA‑ISSA Annual Meeting will kick off in Austin, and this year’s AEMA Technical Session promises a strong, forward‑looking program. Scheduled for Thursday, February 19 from 1:15 to 4:15 PM, the session will guide attendees through key updates and emerging advancements in asphalt emulsion technology.

The afternoon begins with Aaron Roy presenting the ongoing work behind the 5th Edition of the Basic Asphalt Emulsion Manual, outlining the revisions and enhancements that will shape this foundational industry resource. Following that, Mike Anderson will provide an update on NCHRP 9‑63, offering insight into the latest developments in emulsion performance testing and specification frameworks.

The session continues with Stormy Brewster, who will highlight current research priorities along with the initiatives positioned to influence future innovation across the emulsion sector. Concluding the program, Charles Taylor, Aaron Roy, and Shafer Soars will lead a forward‑looking discussion on what’s new and what’s ahead for asphalt emulsions, touching on emerging technologies, evolving market needs, and the trends shaping the future of the field.

Submitted By: Ricardo Romero | Location: Las Vegas, NV | Dates: January 19-22, 2026

• Synergy Group & RoadResource.org: The PPRA Synergy team (AEMA + ARRA + ISSA) continues to drive enhancements for RoadResource.org, our industry’s digital resource hub. The site provides technical reference information, decision tools, and network optimization calculators. It is built and maintained by dozens of volunteers and industry leaders. Learn more about RoadResource.org. Recent work includes refining content under “Treatment Toolbox,” improving interactive diagrams, and prioritizing usability for agencies and other decisionmakers. Learn more on how this free resource helps roadway owners.
• Environmental Product Declarations (EPDs): In response to growing market and regulatory demands for sustainability transparency, AEMA has been actively leading the industry’s efforts to develop Environmental Product Declarations (EPDs) for asphalt emulsion treatments. This work is essential to demonstrating the environmental benefits of our products through credible, third-party verified data — particularly as owners, DOTs, and federal agencies begin requiring EPDs for material selection and funding eligibility.

• Developed data collection frameworks specific to asphalt emulsions and emulsion-based treatments, ensuring our industry's unique processes and products are accurately captured.
• Collaborated with a third-party LCA consultant to establish a path forward for industry-average EPDs based on ISO 21930 standards and Product Category Rules (PCR) tailored to our materials.
• Collected and validated life cycle inventory (LCI) data from member companies, a major milestone made possible by strong member participation and transparency.
• Coordinated with parallel industry initiatives to align terminology, methodology, and system boundaries, ensuring EPDs are comparable and usable across pavement preservation sectors.

• ITC (International Technical Committee): The technical committees continue to lead in advancing best practices, defining quality and specification standards, responding to technical queries, and producing publications such as manuals and guidelines. Our members’ involvement ensures that these standards reflect real world scenarios with operational, production, and field realities always considered and reviewed by the group. The work of this group is vast, and I welcome you to visit the Let’s Get Technical articles that are included in our each Emulsion Notes issues.

• Leadership Development Team: Engaging the next generation is vital. The Leadership Development Team, its LEAP program, and related group activities are helping newer professionals grow their technical skills, leadership, and network within the industry. These opportunities are being expanded, and we are seeing growing participation and enthusiasm.

• Awards & Facility Certification: Recognizing excellence remains a key tool for promoting quality, visibility, and innovation. The Awards committees have evaluated strong nominations, celebrating outstanding projects, agency or contractor performance, and innovation in our industry. Similarly, certification of facilities (e.g. for emulsion quality, environmental or operational practices) has been progressing; our efforts here help elevate standards and trust in our products. (Insert specific data or recent certifications if you have them.)

• Other Committee Work: Across membership, technical response, standards, and sustainability committees, there are ongoing efforts to address specification harmonization, responding to regulatory changes, contributing to educational events and webinars, updating technical manuals, and improving member services.

• Access to current technical guidance, standards, and specification developments.
• Resources and tools that help both manufacturers and agencies make informed decisions.
• Visibility and recognition in the industry via awards, certification, and outreach.
• Opportunity to influence the direction of policy, regulation, and standard setting.
• Educational and networking opportunities, including participation in committees, meetings, the annual meeting, and via Road Resource offerings.

Submitted By: Alan Campos, Pavement Recycling Systems

Dr. Andrew Braham, Professor of Civil Engineering at the University of Arkansas (U of A), hosted the LEAP Program for an exclusive tour of the university and its graduate asphalt program. The visit began with a networking session between LEAP professionals and PhD candidates. This exchange allowed industry representatives—including lab managers, emulsion plant managers, and logistics experts—to demonstrate the vast scope of the asphalt industry.

In return, students presented their semester-long group projects, which covered:
• Comparison of Lab-produced Asphalt Emulsions by Measuring Equipment Type
• Comparative Life-Cycle Cost Analysis of Flexible and Rigid Pavements
• Development of New Storage Stability Testing Methods for Asphalt Emulsions
Following these thought-provoking presentations, Dr. Braham led a walking tour of the campus, highlighting the Bell Engineering Center, the stadium, and the university's famous Senior Walk.

The second day began at the Engineering Research Center (ENRC) with technical presentations regarding material particle size, sealant materials for FDR, and prime and tack coat optimization. The itinerary concluded at the new state-of-the-art Grady Harvell Civil Engineering Research Center. This facility featured impressive setups, including vertical 3-D printing and structural stress analysis testing. Attendees also inspected the TREAT Mobile lab and specialized equipment, such as the R.C. chip sealer and slurry spreader which are impressive as they open the door to new constructions techniques and safety.

This Oregon State University study sought to develop and validate practical test methods for evaluating aggregate–binder adhesion and chip retention in emulsion-based chip seal systems. The goal was to improve construction quality and long-term durability in field applications. As budgets tighten and pavement preservation gains emphasis, chip seals remain a leading strategy for cost-effective maintenance; however, issues such as stone loss and raveling can limit their performance in certain conditions.

Methods:

Three complementary tests were evaluated: a Modified Sweep Test (ASTM D7000) using a battery-powered spin scrubber, a Modified Vialit Test (EN 12272-3), and a Pull-Off Test measuring direct tensile bond strength at 5 °C and 25 °C. The study examined two polymer-modified emulsions — CRS-3P (cationic) and HFRS-2P (anionic) — applied to aggregates from Pendleton and Woodburn, Oregon. Both aggregates were predominantly siliceous with minor calcium and iron content; the Woodburn aggregate was slightly smaller and less flaky, though chemically similar to Pendleton.

Results:

All three test methods demonstrated strong correlation (R² > 0.7) and consistent results across curing conditions. Adhesion improved markedly from 3 to 24 hours of curing, with diminishing gains beyond that period. Failure modes varied by temperature — ohesive within the binder at 25 °C and adhesive at the aggregate interface at 5 °C. The HFRS-2P anionic emulsion exhibited better tolerance to dusty aggregates than the cationic CRS-3P system. Slightly damp aggregates (<3 % moisture) provided the best chip retention, especially with cationic emulsions, while dry or dusty aggregates showed the highest chip loss. Smaller, less flaky aggregates also improved retention regardless of chemistry.

Conclusions:

The modified Sweep and Vialit tests offer rapid, inexpensive, and portable methods for assessing chip seal adhesion in the field. The study recommends establishing practical thresholds — such as a bond strength around 100 kPa and chip loss below 8 % — to support construction quality control and acceptance criteria. Future work will expand to include additional aggregate mineralogies, binder chemistries, and long-term durability studies to strengthen the correlation between adhesion performance and field chip loss.

Baran, S., Sukhija, M., & Coleri, E. (2025). Assessment of aggregate-binder adhesion through field-applicable modified sweep, Vialit, and pull-off Tests. Construction and Building Materials, 490, 142495. https://doi.org/10.1016/j.conbuildmat.2025.142495 

Rethinking Demulsibility: Is It Time to Consider the Breaking Index?

In every technical field, specialized terminology often becomes second nature to those within it — yet remains opaque to outsiders. The asphalt emulsion industry is no different. One term frequently referenced but seldom unpacked is demulsibility. So, what does it mean, and why is it important?  In essence, demulsibility is an indirect measure of emulsifier content of an emulsion, most commonly applied to rapid-setting grades like RS-2 or CRS-2. It offers insight into how quickly an emulsion will “break”— that is, separate into asphalt and water — under controlled conditions.The test method varies depending on whether the emulsion is cationic or anionic. A chemical breaking agent — calcium chloride for anionic emulsions or sodium docusate for cationic — is added to a sample to neutralize the emulsifier. Once neutralized, the emulsion destabilizes, and the degree of separation is recorded as its demulsibility. In practice, higher emulsifier content stabilizes the emulsion, resulting in lower demulsibility. This makes demulsibility a useful proxy for set speed, especially in applications like chip sealing, where early aggregate retention is critical.

Limitations of the Demulsibility Test:

Despite its simplicity, the demulsibility test has notable limitations. It is not applicable to slow- or quick-setting emulsions—such as those used in tack coats, fog seals, or micro surfacing—where specifications often lack any measure of set speed. In these cases, the designer relies on performance metrics and experience to guide formulation. This gap in standardized testing has led to discussion on the applicability of the Breaking Index (BI) test, widely used in Europe.

Introducing the Breaking Index Test:

The Breaking Index test offers a more versatile and realistic approach. Instead of relying on chemical agents tailored to emulsion charge, the BI test uses silica flour, a mineral-based material, to break the emulsion. The amount of silica required to induce breaking is recorded as the emulsion’s Breaking Index—with higher BI values indicating greater emulsion stability. Key advantages of the BI test include:

• Real-world relevance: It uses aggregate mineralogy to simulate actual field conditions.
• Charge independence: Unlike demulsibility, which requires different reagents for cationic and anionic emulsions, the BI test applies uniformly across all emulsion types.
• Broad applicability: It provides meaningful data for slow-set (SS), quick-set (QS), medium-set (MS), and rapid-set (RS) emulsions, including their cationic counterparts.

This opens the door to a broader conversation: Could the Breaking Index test offer a more consistent and practical measure of emulsion set behavior across all grades? 

The Breaking Index(BI) test, standard EN-13057-1, uses typical laboratory equipment: stirrer, balance, funnel, constant temperature bath.  A known mass of emulsion is mixed with filler until the emulsion is completely broken.  Results are reported as the amount of filler necessary to break the emulsion.  The standard requires two replicates vs. the three required for AASHTO T59. BI introduces a surface area component to the breaking of the emulsion which is important to field performance. BI Is faster than demulsibility as it does not require hours in the oven to lose all of the water.  

Bottom line: Breaking Index seems to correlate better with field breaking while demulsibility correlates with formulation stability.  Some data below provided by Ingevity, shows the two tests head-to-head.  The BI data is repeatable and shows some snappiness to emulsions that would not test that way per our current standard.  Perhaps it is time to reconsider this meaningful test.  

New Test Methods for Quality Control of Asphalt Emulsions used in Chip Seal Application

This article is by Alvaro Gutiérrez Muñiz, presented at the 8th International Symposium on Asphalt Emulsion Technology (ISAET '24), introduces a set of innovative rheological testing protocols for asphalt emulsions. These methods are designed to better simulate the real-world conditions encountered during chip seal applications, such as spraying, rolling, and exposure to traffic and temperature extremes. The study emphasizes the importance of controlling process variability to improve the quality and performance of chip seal treatments.

What makes this work particularly important is its shift from traditional empirical specifications, like Saybolt Furol viscosity and particle charge tests, to performance-based criteria using Dynamic Shear Rheometer (DSR) technology. By measuring viscosity at different shear rates and temperatures, the new methods provide a more accurate and predictive understanding of how emulsions behave during application and in service. This is crucial for ensuring proper aggregate retention, minimizing bleeding, and preventing cracking, especially under varying climate and traffic conditions.
The novelty of the test lies in its multi-shear-rate approach. For example, low shear rate viscosity (0.1 s⁻¹) is used to assess storage stability and post-application performance, while high shear rate viscosity (1000 s⁻¹) evaluates pumpability and sprayability. Additionally, the study introduces yield energy as a metric for high-temperature flow resistance and flexibility index for low-temperature brittleness which are absent in conventional testing. These parameters are directly linked to field performance, making the tests more relevant and practical.

This article presents a significant advancement in asphalt emulsion quality control by aligning laboratory testing with field performance requirements. The proposed methods offer a more field-driven framework for evaluating emulsions, helping engineers and manufacturers produce materials that are better suited to the demands of chip seal applications. 

Gutiérrez Muñiz, A. (2024). New Test Methods for Quality Control of Asphalt Emulsionsused in Chip Seal Application. Presented at the 8th International Symposium on Asphalt Emulsion Technology (ISAET '24), Washington D.C., November 4–6, 2024. Asphalt Emulsion Manufacturers Association (AEMA) and International Bitumen Emulsion Federation (IBEF). Retrieved from https://www.ibef.net/wp-content/uploads/2025/01/nov._5__session_2__-_p5_-_al.pdf

Characterizing Stability of Asphalt Emulsions Using Electrokinetic Techniques

This study discusses an alternative approach to evaluating the stability of asphalt emulsions using electrokinetic techniques, specifically focusing on electrophoretic mobility and zeta potential. Traditional established methods like demulsibility tests are often qualitative and limited in their ability to predict field performance. The authors propose that electrokinetic measurements can offer a more quantitative and sensitive assessment of emulsion stability by analyzing the behavior of charged asphalt particles in an electric field. These measurements reflect the interaction between asphalt droplets and the aqueous phase, which is critical to understanding how emulsions break and cure.

The researchers conducted experiments on various cationic emulsions, examining how factors like dilution, pH, and ionic concentration affect their electrokinetic properties. They found that emulsions with higher zeta potential values exhibited greater stability, while those with lower values were more prone to breaking. The study also demonstrated that electrophoretic mobility could be used to track changes in emulsion behavior over time, offering insights into how emulsions age and respond to environmental conditions. This method proved to be reproducible and sensitive to formulation changes, making it a promising tool for both research and quality control.

Ultimately, the article concludes that electrokinetic techniques can serve as a valuable complement or alternative to conventional emulsion tests that may not offer the same field performance predictability such as the standard demulsibility tests. By providing a deeper understanding of the physicochemical interactions within emulsions, these methods could help formulators design more robust products and enable agencies to better predict field performance. The authors suggest further research to refine the technique and explore its application across a broader range of emulsion types and field conditions.

Banerjee, A., Bhasin, A., & Prozzi, J. Characterizing Stability of Asphalt Emulsions Using Electrokinetic Techniques. Journal of Materials in Civil Engineering, 25(1), 78–85. https://doi.org/10.1061/(ASCE)MT.1943-5533.0000552

Asphalt Emulsion Specifications & Testing Methods

In North America, asphalt emulsion specifications primarily follow ASTM and AASHTO standards that address both the as-received emulsion and the recovered residue. ASTM D977 (AASHTO M 140) covers anionic emulsions, while ASTM D2397 (AASHTO M 208) covers cationic emulsions. These specifications include grade classifications and reference key testing methods used for quality control, performance, and verification of consistency across production batches (ASTM, 2024a, 2024b).

Routine quality control is based on ASTM D244 (AASHTO T 59), which measures water content, residue by distillation, Saybolt Furol viscosity, particle charge, demulsibility, settlement, and sieve test results. Additional test methods such as ASTM D6930 (storage stability), ASTM D6933 (oversized particles), and rotational viscosity testing (ASTM D7226/D7496) are commonly used by agencies and producers (ASTM, 2023a, 2023b, 2022). Residue testing then characterizes binder properties through penetration, softening point, and rheological analyses.

Ongoing Research: Testing the Emulsion Itself

Traditional specifications focus on the recovered residue, but current research emphasizes characterizing the emulsion itself. Three areas are gaining traction:

1. Particle Size Distribution (PSD): Laser diffraction and dynamic light scattering (DLS) are increasingly used to measure droplet size and distribution. PSD directly affects emulsion stability, pumpability, and breaking behavior. Narrow distributions indicate better stability and uniform field performance. Researchers have proposed draft specifications defining D10/D50/D90 ranges to correlate particle uniformity with storage stability and coating behavior (Diaz Romero, 2022; Kiihnl, 2020; Turben, 2024; Braham, 2024).

2. Zeta Potential: Quantitative charge measurement (zeta potential) helps explain emulsion stability and aggregate adhesion mechanisms. This test goes beyond simple “cationic vs. anionic” classification and offers a measurable indicator of electrostatic stability and coating potential. Recent work has linked zeta potential trends to aggregate type, water chemistry, and polymer modifiers (Miller, Hensley, & Rushing, 2025; Liu & Zhang, 2020; Airey, Rahman, & Collop, 2003).

3. Emulsion Rheology: Rotational viscometry at low shear rates measures flow characteristics and correlates to handling, storage, and mix time performance—offering a more realistic picture than Saybolt Furol viscosity alone. Advanced rheological profiles are being used to relate emulsion flow properties to workability and spray performance across temperature ranges, particularly in polymer-modified systems (Chen, Xiao, & Putman, 2022; FHWA, 2021; TRB, 2023; Braham, 2019).

These emerging testing approaches are helping bridge the gap between laboratory specifications and real-world performance. While ASTM and AASHTO specifications continue to rely on residue-based acceptance, direct emulsion characterization provides valuable insights into formulation stability, compatibility with aggregates, and long-term durability—especially for polymer-modified and specialty emulsions (Braham, 2019, 2024).

References

• Airey, G. D., Rahman, M. T., & Collop, A. C. (2003). Study of the electrical properties of cationic bitumen emulsions. Advances in Colloid and Interface Science, 105(1–3), 83–106. https://doi.org/10.1016/S0001-8686(03)00144-1
• American Society for Testing and Materials. (2024a). ASTM D977–24: Standard specification for emulsified asphalt (anionic). ASTM International.
• American Society for Testing and Materials. (2024b). ASTM D2397–24: Standard specification for cationic emulsified asphalt. ASTM International.
• American Society for Testing and Materials. (2023a). ASTM D244–23: Standard test methods for emulsified asphalts. ASTM International.
• American Society for Testing and Materials. (2023b). ASTM D6930–23: Standard test method for settlement and storage stability of emulsified asphalt. ASTM International.
• American Society for Testing and Materials. (2023c). ASTM D6933–23: Standard test method for oversize particles in emulsified asphalt. ASTM International.
• American Society for Testing and Materials. (2022). ASTM D7226 / D7496–22: Rotational viscosity of emulsified asphalts. ASTM International.
• Braham, A. F. (2019, April 24). Building better micro surfacing and slurry seals [Webinar slides]. Transportation Research Board.
• Braham, A. F. (2024, April 10). Asphalt emulsions in flexible pavement preservation: Part 1 [Workshop presentation]. South-Central Pavement Technology Center, University of Arkansas.
• Chen, Y., Xiao, F., & Putman, B. (2022). Factors influencing the droplet size of asphalt emulsion during fabrication. Coatings, 12(5), 575. https://doi.org/10.3390/coatings12050575
• Diaz Romero, P. L. (2022). Refining particle size specification for asphalt emulsion (Master’s thesis, University of Arkansas). University of Arkansas Institutional Repository. https://scholarworks.uark.edu/etd/6000
• Federal Highway Administration (FHWA). (2021). TechBrief: Advances in asphalt emulsion characterization and performance testing. Publication No. FHWA-HIF-21-028. U.S. Department of Transportation.
• Kiihnl, L. P. (2020). Best practices for asphalt emulsion particle size analyses using a Coulter counter (Master’s thesis, University of Arkansas). University of Arkansas Institutional Repository. https://scholarworks.uark.edu/etd/3657/
• Liu, C., & Zhang, J. (2020). ζ potential as a measure of asphalt emulsion stability. Energy & Fuels, 34(12), 15896–15907. https://doi.org/10.1021/acs.energyfuels.9b03565
• Miller, C., Hensley, M., & Rushing, T. (2025). Probing the stability of emulsified asphalts: A dual analysis of zeta potential. Fuel, 370, 132103. https://doi.org/10.1016/j.fuel.2025.132103
• Transportation Research Board (TRB). (2023). E-Circular 291: Asphalt emulsion technology and field performance update. Transportation Research Board of the National Academies.
  Turben, T. (2024). Impact of equipment type on measured particle size of civil engineering materials and draft procedure for asphalt emulsion PSA (Master’s thesis, University of Arkansas). University of Arkansas Institutional Repository. https://scholarworks.uark.edu/etd/5489/
• Wang, H., Zhang, W., Liu, X., & Li, Z. (2011). Experimental study on the stability of asphalt emulsion for CA mortar by laser diffraction technique. Construction and Building Materials, 25(10), 4152–4159. https://doi.org/10.1016/j.conbuildmat.2011.04.065
• Zhang, X., Hu, W., & Han, R. (2022). Effects of oil/asphalt emulsion formulation on particle size and stability. Transportation Research Record, 2676(5), 512–523. https://doi.org/10.1177/03611981221100512
   
   

As the seasons shift across North America, the Asphalt Emulsion Manufacturers Association (AEMA) Industry Technical Committee (ITC) shares key updates impacting our members and the broader pavement preservation community.

EPA Issues Interim Final Rule on TCE

On September 15, 2025, the Environmental Protection Agency (EPA) issued an interim final rule revising compliance deadlines for Trichloroethylene (TCE) under the Toxic Substances Control Act (TSCA). Public comments are being accepted until October 17, 2025, and can be submitted via:

• TCE.TSCA@epa.gov
• TSCA-Hotline@epa.gov
• Regulations.gov – Docket #EPA-HQ-OPPT-2020-0642

Some energy-producing sectors may receive deadline extensions through 2028. If your organization is navigating the transition away from TCE, AEMA’s Ask an Expert feature on the new AEMA website is available to support you.

Upcoming Webinar: Driving Innovation in Asphalt Emulsions

AEMA’s Leadership Development Team will host a webinar titled “Driving Innovation: A Summary of Asphalt Emulsion Articles” on Thursday, October 30th from 12–1 PM EST. This lunch-and-learn session will cover 10 key topics in 30–45 minutes, offering insights into emerging trends and technologies in the asphalt emulsion space. Please share this opportunity across your teams and networks.

Regional & National Meetings

Conference season is approaching quickly. Mark your calendars for these key industry gatherings:

• NESMEA-NEAUPG: October 28, 2025, in Harrisburg, PA
• SEAUPG: November 18–20, 2025, in Charleston, WV
• TRB Annual Meeting: January 11–16, 2026

Save the Date: 2026 AEMA–ARRA–ISSA Annual Meeting

For the 23rd consecutive year, the Asphalt Emulsion Manufacturers Association (AEMA), the Asphalt Recycling & Reclaiming Association (ARRA), and the International Slurry Surfacing Association (ISSA) are proud to pave the way once again — this time in the heart of Austin, Texas, from February 17–20, 2026, at the Hilton Austin. As we gather in one of the most dynamic cities in the country, we’ll be laying the groundwork for the future of pavement preservation and recycling through collaboration, innovation, and shared expertise.

Explore the New AEMA Website

Have you seen the new AEMA website? It’s interactive, user-friendly, and packed with resources. Be sure to explore and share it with colleagues across the industry.

AI Study on Impacts of Global Energy Transition on Asphalt Binder Supply Chain

The Asphalt Institute (AI) Foundation commissioned a study by Wood Mackenzie Consulting titled, "Analyzing the Petroleum Asphalt Binder Supply Chain under Energy Transition Scenarios." The study examines the impacts of global energy transition on the asphalt binder supply chain, providing strategic insights for researchers, infrastructure planners, policymakers, and industry stakeholders.

The study and a free webinar explaining the findings are available through the link found here.

September Washington DC Fly-In

The Fall FP2 fly-in is scheduled for Wednesday and Thursday, September 10-11th. More information on this will be forthcoming – meetings will run from Wednesday, September 10th at 11:00 am – 4:00 pm Thursday, September 11th. The timing will be good to meet with your members of Congress and discuss pavement preservation and recycling needs for the next highway bill.

Please email Rick Church at rickc@cmservices.com if you plan to attend so we can schedule meetings with your representatives.

We have a block of rooms, as long as available, at a new hotel in Washington, the Arlo Washington, DC hotel. It is located at 333 G Street, NW which is close to Capitol Hill. The website is arlohotels.com. To get the discounted rate for FP2 use the code: NGSARAH in the PROMO code section when booking. The rates are currently just under $250 per night. Please let us know if you are intending to attend.

Please let us know if you have any questions. FP2 is pleased to represent the Pavement Preservation industry in Washington DC and in important research helping to demonstrate the value of Pavement Preservation.

LEAP Program Tour: Flint Hill Resources

The LEAP Program started off the day at the Pine Bend Refinery in Rosemount, Minnesota; where we were welcomed at their main office by Flint Hills Charles Boan, General Manager of Asphalt and Gayle Fee, Asphalt laboratory manager with a wonderful presentation on the vast operation of the company. Afterwards the LEAP group was given a bus tour around the refinery and were able to see hundreds of miles of pipelines in this facility required to produce diesel, jet fuel, coke, C3/C4, and heavy oil products using all the materials from the process of distillation accompanied by testing at different stages with the onsite facility.

The refinery utilizes many products from the facility itself as well as other Flint Hills facilities from the ammonium thiosulfate for fertilizer to coke.  The facility over the last five years been EPA ENERGY STAR certified for energy efficiency for manufacturing plants and the water  treatment for utilization of bacteria to consume byproduct for reconstituted water.

The Pine Bend refinery was spectacular to witness in person, especially all the working parts and continue further in the day at the following facilities. The 350,000 barrels of crude oil refined daily, and the 25,000 barrels of asphalt produced show how the Flint Hills refinery produce ten percent of asphalt need in the United States.

We headed to lunch at a Buffalo tap and grill in the town of Savage, Minnesota where we visited the Flint Hills Polymer facility in the afternoon. The introduction on how the asphalt binders were modified down stream from the products of the refinery.

Back Row: Ellie Kenny, Kim Gessner, Jenny Sasser, Alan Campos, Jorge Campos, Carlos Lopez, Christine Hagele, Kristy Eisentrager. Front Row: Donna Kwapis, Ricardo Romero.

The SBR (Styrene butadiene rubber) and SB latex for the modification of certain products at the Polymer facility. On a decent day, 70 loads per day, busier days would be more than 100 loads per day at the facility. HMI (Human Machine Interface) controls the ability for drivers to load themselves after initial training to the process of loading. Testing is done first batch of the day from the sampler at the rack and the Dynamic Shear Rheometer (DSR) test done at location while the rest of the sample taken to the Emulsions laboratory for further testing at the Emulsions plant facility.

To round up the tour we visited the Emulsion Plant in St. Paul, Minnesota located beautifully next to the Mississippi River and able to see the complete process of manufacturing from crude oil to asphalt emulsion products. The plant showed the ultimate process in producing the emulsion asphalt with the same dedication of the previous facilities in the cleanliness and environmental safety. It was stunning to be able to see the Flint Hills Resources facilities and the expansive systems at place in all three of the tour facilities.

Member Spotlight: Charles Taylor, Ergon Asphalt & Emulsions

I Charles Taylor, currently in the role of Regional Technical Operations Manager for Ergon Asphalt and Emulsion and former LEAP member. I was part of the 2023-2024 LEAP class. Being a part of the LEAP program was a wonderful experience. It is a program that I foresee will continue to flourish and offer great opportunities and knowledge to people in the industry. The LEAP program not only delivers essential education of the industry, but it also builds lasting relationships among professionals in our field. This program is for anyone in our industry, regardless of background or experience. LEAP offers a fantastic opportunity to gain knowledge about emulsions, raw materials like surfactants, refined liquid asphalt, and aggregates. During my tenure in the LEAP program, we visited various sites that ranged from rock quarries to various types of laboratories, emulsion manufacturing facilities, refineries, and congress in DC. During each tour it was something that I learned or found out that I can use in my everyday work duties to help improve my knowledge and skills. One of the tours that stood out to me was the TCC Fly-In that was held in Washington DC. It was a unique chance to team up with industry peers and bring AEMA message directly to the senators and congress in a more personal setting that can be specific to your geographic area. In addition to the various tours, we also completed a University of Arkansas course that was beneficial and packed with valuable information. The course can be extremely useful for newcomers in the industry but also a great refresher for the people that have been in the industry for a while. Since completing LEAP, I have noticed many of us have gone on to work in the AEMA LDT (Leadership Development Team) group and continue to advance in both our industry and our professional relationships. Personally, I joined AEMA LDT and am currently the leader of the AEMA AI specification task force. LEAP can be seen as the bridge between the gap of the newcomers into the industry, which are enthusiastic to learn the industry that just do not know where to start or ask for help and the seasoned industry people. I highly recommend LEAP to anyone. Leap a program that is helping the contented push to grow the industry. The LEAP program helped me forge friendships that I still cherish today. I look forward to every opportunity to reconnect with my group and catch up on each other’s lives and careers.

In this edition of Let’s Get Technical, we decided to take it back in time.   Please enjoy these blasts from the past that in some cases remain relevant today.  If you make it to the last review, inquiring minds would like to know if there is any update from Oregon’s stance on rubber modified chip seals.

A General Method of Design for Seal Coats and Surface Treatments:

Norman McLeod’s A General Method of Design for Seal Coats and Surface Treatments laid the groundwork for how engineers design and apply protective layers to roads. These treatments extend pavement life, improve safety, and reduce maintenance costs. McLeod’s method introduced a structured way to calculate how much stone and asphalt binder should be used based on factors like traffic volume, aggregate shape, and surface texture. His approach was one of the first to combine practical field experience with mathematical design.

One of the most important contributions of the paper is its focus on aggregate quality and shape. McLeod emphasized that the size and geometry of the stone used in surface treatments directly affect how well the treatment performs. He introduced the concept of the Average Least Dimension (ALD) to help engineers select aggregates that would embed properly in the binder and resist dislodging under traffic. This was a major step forward in improving the durability and effectiveness of surface treatments.

McLeod also developed a formula for determining the correct amount of asphalt binder, needed to hold the aggregate in place. His equation accounts for traffic conditions, surface roughness, and the absorption characteristics of the pavement and aggregate. This allowed engineers to tailor treatments to specific environments, reducing waste and improving performance. He also provided practical advice on construction techniques, such as rolling procedures and traffic control, which are still relevant today.

For roads requiring multiple layers of treatment, McLeod also explored multi-layer designs, adjusting binder and aggregate quantities for each layer. This approach is especially useful for high-traffic roads or those in harsh climates. His recommendations for seasonal timing and binder selection based on temperature remain valuable for modern engineers working in diverse conditions.

Even decades later, McLeod’s paper is relevant in pavement engineering. Its blend of theory and field-tested practice continues to influence modern design standards and specifications. As infrastructure ages and budgets tighten, the need for cost-effective, long-lasting surface treatments is more critical than ever, making his work important and relevant today.

McLeod, Norman W. "A General Method of Design for Seal Coats and Surface Treatments." Proceedings of the Association of Asphalt Paving Technologists, vol.38, 1969, pp. 537–628.

Report on Laboratory Generation and Evaluation of Paving Asphalt Fumes (Kriech, Wissel, et al., 1999):

The 1999 study by Kriech, Wissel, and colleagues, published in the Transportation Research Record, set out to answer an important question: could asphalt paving fumes be recreated in the laboratory in a way that truly represented what workers experience in the field. By creating a controlled fume generation system, the researchers were able to compare lab-generated samples with emissions collected during real paving projects.

Their results showed that the laboratory method closely matched the chemical makeup of field fumes, especially when looking at polycyclic aromatic compounds and how vapors and particulates were distributed. This confirmed that the lab setup could be trusted as a stand-in for field studies, an important step in assessing worker exposure to asphalt fumes. Another key finding was that the concentrations of harmful compounds, such as carcinogenic PACs, were relatively low compared with other industrial emissions. This helped form a scientific basis for later occupational health guidelines and exposure limits.

Since its publication, the paper has been cited in occupational hygiene studies, NIOSH evaluations, and toxicological reviews. It provided the groundwork for later research into worker exposure, especially in comparing field and laboratory conditions. Even today, it remains relevant as new paving technologies are introduced. Warm-mix asphalt and asphalt emulsions operate at lower temperatures, producing significantly fewer fumes, and this paper is often referenced to highlight the advantages of these methods over traditional hot-mix paving.

In short, the work of Kriech and Wissel continues to stand as a cornerstone in the field. It demonstrated that laboratory studies could meaningfully reflect real-world paving conditions and gave researchers and regulators a dependable framework for evaluating asphalt fume exposure—knowledge that is still applied in today’s discussions of worker safety and the benefits of emulsion-based paving.

Citation: Kurek, J. T., Kriech, A. J., Wissel, H. L., Osborn, L. V., & Blackburn, G. R. (1999). Laboratory Generation and Evaluation of Paving Asphalt Fumes. Transportation Research Record: Journal of the Transportation Research Board, 1661, 35–40. https://doi.org/10.3141/1661-06

Summary of Evaluation of Rubber-Asphalt Chip Seals in Oregon (1982, ODOT):

• Key Takeaway: Rubber-asphalt chip seals in Oregon (1977–1981) did not justify their higher cost, offering little to no long-term performance advantage over conventional chip seals.
• Purpose: ODOT tested rubber-asphalt chip seals (made by blending ground scrap tire rubber with hot asphalt binder) on several highway sections in Oregon between 1977–1981. The goal was to compare cost, performance, and constructability with conventional chip seals.

Methods:

• Rubber-asphalt binders were mixed with 18–22% ground tire rubber.
• Test sections: U.S. 97 (Klamath Falls–Bend), U.S. 20 (Burns), OR 19, and a few others.
• Compared rubberized chip seals with adjacent standard ODOT chip seals.
• Evaluated performance based on bleeding, raveling, chip retention, and overall surface condition over 3–4 years.

Performance:

• Early years (1–2 yrs): Rubber chip seals showed good chip retention and flexibility, sometimes better than conventional.
• Later years (3–4 yrs): Performance differences disappeared; both types showed similar levels of cracking, raveling, and wear.
• Bleeding issues were more frequent with rubber-asphalt, especially in hot weather.
• No clear evidence of significantly longer life compared to conventional chip seals.

Cost:

• Rubber-asphalt chip seals were ~1.5 to 2 times more expensive than conventional chip seals.
• High costs came from: Special mixing requirements, Transport of rubber additive, Slower construction (temperature-sensitive).

Constructability:

• More difficult to handle: Rubberized binder required higher temperatures (375–400°F), Shorter workable time window, Specialized handling equipment
  

Conclusions:

• Rubber-asphalt chip seals were not cost-effective compared to ODOT’s standard chip seals. Performance was comparable, not superior, despite higher costs and added construction completion time. Do not adopt rubber-asphalt chip seals for routine use in Oregon. Suggested continued observation in warmer states (Arizona, California) where climate might favor performance.

Beecroft, D. W., Hardy, R. L., & Steyskal, R. A. (1982). Evaluation of rubber-asphalt chip seals in Oregon (Final Report, Research Project No. 75-02). Oregon Department of Transportation, Research Unit.

The LEAP program arrived at the Ingevity Headquarters in North Charleston, SC in April and were welcomed by Aaron Walker. We took a tour of the office and were given a great presentation of some of the products they offer as well as some insight into their continued efforts to always improve environmental impacts. The tour then continued at the Ingevity Manufacturing Plant in North Charleston. After all PPE and sign ins were complete, we were able to look at how their production plant operates. We also toured Ingevity’s lab, which was amazing. The amount of equipment it takes to make sure their products are meeting all the state standards is quite amazing.

Picture left to right: Jorge Campos, Ellie Kenny, Kim Gessner, Marty Powell, Carlos Lopez, Kristy Eisentrager, Christine Hagele, Aaron Walker, Charity Cook, Jennifer Sasser, Alan Campos. Front Ricardo Romero

The LEAP program would like to thank the entire Ingevity team for their very educational tours and hospitality.

In 2024, the following was included in House Bill 265 for Kentucky:

(26) Microsurfacing: It is the intent of the General Assembly that the Transportation Cabinet shall no longer use microsfurfacing by the year 2030.
 
Of course, this upset the microsurfacing supporters in the maintenance department along with the microsurfacing contractors. 

For some background, the state began the use of microsurfacing in 2008, but in my opinion, projects really got going with over the next 7 years. In 2020, the state moved to only using double micro courses.  Double micros are let head-to-head with thinlays. The state spends anywhere from $20-$30 million per year on these jobs.  It depends on the year if the bulk of the money goes to microsurfacing or thinlays.  

Every year or every couple of years, the maintenance department justifies the use of microsurfacing as a tool in the toolbox. They believe this data driven approach to the increased longevity of the road shows that they have been making the correct decision on treatments.  Now, that’s not to say that there haven't been a few issues along the way. There have been failures, but those that I am aware of have been due to base failures or other issues where the microsurfacing never should have been used.

In my discussions with the state, there doesn't seem to be an abundance of concern over this bill. They have slowed down micro lettings for 2025, but plan to pick up with some in the fall.   Additionally, microsurfacing is being looked at for improving some of the current friction issues in the state. The microsurfacing industry has been very active with Kentucky legislation explaining the benefits of their product.  It seems as if the two are doing what they can with the time left to change the legislature’s mind.

The only two things that really come up from the HMA industry are the cost and quality of the microsurfacing projects. In 2025, microsurfacing is expensive as it has ever been in the state and the HMA contractors believe that the thinlay will outlast the microsurfacing. The state has plans to help go after the cost by letting more projects together.  

My biggest concern through all of this is potential spread.  Even discussing this may cause movements in other states or further movements in KY.  

Microsurfacing in Ohio (On-Going Trial and Success)

The article “Micro Surfacing in Ohio” from AsphaltPro Magazine highlights a pavement preservation project led by the Ohio Department of Transportation (ODOT) at Maumee Bay State Park. Facing harsh freeze-thaw cycles and high moisture levels due to its proximity to Lake Erie, the park required a durable, low-maintenance solution. ODOT selected micro surfacing as a cost-effective treatment to protect the pavement from moisture and oxidation while improving surface friction for safety. The project involved sealing cracks, applying a tack coat, and using a spreader box to evenly apply the micro surfacing mixture.

The existing pavement, a 15-year-old hot mix asphalt surface, was still in good condition, making it an ideal candidate for micro surfacing. This aligns with best practices that recommend applying surface treatments before significant structural deterioration occurs. The treatment not only extended the pavement’s life but also minimized disruption to park visitors, which is crucial for a high-traffic recreational area.The article notes that micro surfacing, when applied correctly, can reduce greenhouse gas emissions by over 44% compared to traditional hot mix asphalt resurfacing.

Overall, the project demonstrates how micro surfacing can be a sustainable and efficient pavement preservation strategy, especially when applied at the right time. It also underscores the importance of product evaluation and performance monitoring in optimizing treatment outcomes for public infrastructure.

https://theasphaltpro.com/articles/micro-surfacing-in-ohio/

Charleston County Advances Pavement Preservation with Innovative Strategies

Charleston County, South Carolina continues to lead by example in the field of Pavement Preservation, embracing a range of forward-thinking, data-driven approaches to extend the life of its roadways and enhance surface performance. Among its current initiatives are the application of advanced surface treatments designed to improve durability and long-term value.

The county is currently conducting its fourth round of pavement condition assessments using a specialized data collection vehicle—building on previous evaluations, the most recent of which occurred in 2021. This ongoing data collection effort plays a critical role in measuring the effectiveness of various treatments over time, including those that undergo performance testing several years after application.

In addition to surface treatments, Charleston County is preparing to launch a new Hot In-Place Recycling (HIR) contract, expected to be bid by the end of the year and implemented in the upcoming construction season. The county is also exploring additional rehabilitation techniques such as Cold In-Place Recycling (CIR) and Cold Central Plant Recycling (CCPR), further diversifying its toolbox of sustainable pavement strategies.
Other innovative treatments being evaluated include double fiber-reinforced micro surfacing, scrub seals followed by cape seals, and various other combinations. These efforts reflect Charleston County’s commitment to exploring new technologies and refining its preservation practices.

A special acknowledgment goes to Mackenzie Kelley, Engineering Manager for Charleston County, whose leadership and dedication have been instrumental in driving these initiatives forward.
Through its commitment to innovation and continuous improvement, Charleston County is setting a strong example for agencies across the region—demonstrating how thoughtful planning, evaluation, and collaboration can lead to more resilient and cost-effective pavement solutions.

Microsurfacing: A 30-Year Review 

Overview:
Microsurfacing is a cold-applied, quick-set pavement preservation technique that has gained widespread acceptance over the last 30 years. Used to address surface wear, fill ruts, and extend pavement life, it offers a cost-effective and sustainable maintenance strategy. This review paper synthesizes three decades of field application, research, and evolving practices.

Core Benefits:
- Performance Enhancement: Microsurfacing restores surface texture, improves skid resistance, and corrects minor surface defects. Rut-filling capabilities improve ride quality significantly [7].
- Cost Efficiency: As a preventive maintenance tool, microsurfacing delays costly rehabilitation or reconstruction. Lifecycle analysis shows significant return on investment [9].
- Minimal Traffic Disruption: Fast cure times allow traffic to return within hours, reducing user delay costs.
- Environmental Sustainability: Cold-mix application reduces energy consumption and emissions compared to hot mix asphalt [6].

Challenges Identified:
- Environmental Sensitivity: Application success is highly dependent on temperature, humidity, and timing. Poor conditions can delay curing and affect adhesion [18].
- Inconsistent Field Results: Early wear, delamination, or poor aesthetics can result from inconsistent materials, inadequate contractor quality control, or improper mix designs [19].
- Data Gaps: A shortage of long-term, multi-climate performance data limits lifecycle modeling and predictive maintenance planning [14].

Innovation & Research Trends:
Ongoing efforts focus on:
- Enhanced mix designs for performance reliability [7].
- Standardization of test methods (e.g., Wet Track Abrasion Test).
- Integration of recycled materials for sustainability.
- Development of performance-based specifications to reduce variability [19].

Conclusion:
Microsurfacing remains a key tool in pavement preservation, balancing performance, cost, and environmental stewardship. While its advantages are well-documented, continued progress hinges on improved data collection, standardization, and adaptive innovations.

Key References:
- [6] Kandhal & Mallick (1997): Emissions study favoring cold-applied methods.
- [7] Shuler et al. (2011): Mix design and performance improvements.
- [9] Galehouse et al. (2003): Cost-effectiveness in preventive maintenance.
- [14] Button & Lytton (2007): Need for long-term performance data.
- [18] Andriescu et al. (2006): Environmental timing effects on performance.
- [19] Morian et al. (2012): Performance-based application guidelines and field challenges.

Member Spotlight: How One LEAP Made All the Difference —

My name is Matthew Gutkaiss, and I was part of the 2023 LEAP class. The LEAP tours, articles, and experiences helped forge friendships that I still cherish today. I look forward to every opportunity to reconnect with my group and catch up on each other’s lives and careers. Since completing LEAP, many of us have gone on to work in the LDT group, continuing to advance both our industry and our professional relationships.

One of the LEAP requirements is to deliver a group presentation to your peers just before graduating. Since that day, I’ve regularly spoken at local association events and even led a few facility tours during the 2025 PPRA event in Richmond. Without that initial push, I may never have developed the confidence to speak comfortably in front of large groups.

We all know that training the next generation can be costly and time-consuming. But the LEAP program, offered through AEMA, not only delivers essential education — it also builds lasting relationships among young professionals in our field. My advice to anyone considering LEAP is simple: absolutely go for it! This program is for anyone in our industry, regardless of background or experience.

LEAP offers a fantastic opportunity to learn about raw materials like surfactants, refined liquid asphalt, and aggregates. The tours provide valuable insight into emulsion manufacturing, testing, and innovations in pavement preservation. Take advantage of every tour you can — and don’t sleep on the TCC Fly-In! It’s a unique chance to team up with industry peers and bring our message directly to federal lawmakers.

Dr. Brahams’ course through the University of Arkansas is packed with valuable knowledge and encourages students to reach out to industry professionals for clarity on unfamiliar processes. Whether you're considering joining LEAP yourself or sending your company’s up-and-comers, I can’t recommend this program enough. See for yourself how impactful it can be!

AEMA is excited to announce the formation of our brand-new Workforce Development Committee, and we’re calling on members like you to help guide its direction. This committee will focus on tackling industry-wide workforce challenges—and your input will shape the initiatives we prioritize.

Take our quick survey to let us know what matters most to your team, your company, and your future workforce. Whether it's training, recruitment, retention, or upskilling — your voice helps us build a stronger, more prepared industry.

Click here to take the survey

Together, we can create solutions that support your success and grow the future of the asphalt emulsion industry!

LEAP Tours Sustainable Emulsions —

Following the 2025 AEMA-ARRA-ISSA Annual Meeting, the newly inducted LEAP class—along with fellow LEAP alumni—visited the production plant and laboratory of Sustainable Emulsions, a division of Pavement Recycling Systems (PRS). During the General Meeting, keynote speaker Aaron Witt introduced a framework that categorizes companies as Losers, Followers, or Winners. This tour made it clear: Sustainable Emulsions is a Winner—a company actively driving progress in the industry.

Upon arriving at the Colton, CA facility, the LEAP group was warmly welcomed by their hosts, led by Jorge Campos, LLC Manager at Sustainable Emulsions. The tour began with a walkthrough of the manufacturing plant, showcasing the diverse services offered by PRS. With capabilities spanning cold milling, concrete recycling, RAP aggregates, and—most recently—asphalt emulsions, PRS demonstrates its commitment to a fully sustainable business model. In its first year, Sustainable Emulsions shipped 25,000 gallons of asphalt emulsion. The team also highlighted the company’s in-house milling software, equipped with Bluetooth remote connectivity, which enhances communication and collects critical data to improve plant performance.

The Sustainable Emulsions team showed a clear dedication to innovation and practical problem-solving. One standout example addressed the challenges of California’s extreme heat and urban “heat island” effects—areas that retain higher temperatures due to dense development. To help combat this, PRS acquired CoolSeal, a reflective pavement technology that reduces asphalt surface temperatures by 10–20°F. The LEAP class later observed this cool pavement in action in the company’s parking lot.

The benefits of Sustainable Emulsions’ 100% employee-owned structure were apparent throughout the visit. The team’s enthusiasm, ownership, and forward-thinking mindset stood out at every stage. From developing innovative machinery that scans milling teeth to reduce waste and costs, to maintaining clean, efficient facilities, the company continues to raise its own standards.

The LEAP group extends its sincere thanks to the Sustainable Emulsions team for their energy, innovation, and hospitality throughout the tour.

Written by: Ellie Kenny, Walker Emulsions

2. Roadvocate Training.

Your New Road Maintenance Tool — A Game-Changer for Road Management

In this article, a recent trainee, Jorge Campos, dives into the Roadvocate Training experience and explores how RoadResource.org empowers public works professionals with practical, data-driven tools. From budget-stretching planners to treatment selectors, this free platform brings real value to the field.

I just wrapped up an insightful three-day Roadvocate Training on RoadResource.org, the free and user-friendly platform developed by the Pavement Preservation & Recycling Alliance (PPRA) — and let me tell you, it’s built to make life easier for anyone managing pavement networks.

This isn’t your average online tool. It’s packed with practical features that make planning, budgeting, and treatment selection smarter and more transparent. You can plug in your own data, test out different scenarios, and get clear, visual insights to support your decisions.

What really stood out?

• Hands-on learning with real, customizable data.
• Intuitive interface—no tech frustrations.
• Expert guidance on when, where, and how to apply treatments.
• Planning tools that help you communicate value, plan long-term, and maximize funding.
  

Bottom line: this platform reflects deep industry knowledge, real-world needs, and a commitment to better roads. If you're in road maintenance or asset management, RoadResource.org isn’t just useful — it’s essential.

Written by: Jorge Campos, Sustainable Emulsions

The research paper investigates the feasibility of using polyphosphoric acid (PPA) to modify emulsified asphalt, focusing on its emulsification characteristics, rheological properties, compatibility, and modification mechanisms. The study prepared PPA-modified emulsified asphalt with different dosages (0%, 0.5%, 1.0%, 1.5%, and 2.0%) and evaluated its properties, including evaporation residue, storage stability, and rheological performance using dynamic shear rheometer tests. Additionally, Fourier transform infrared spectroscopy (FTIR) and fluorescence microscopy (FM) were employed to analyze the chemical composition and microscopic characteristics of the modified asphalt.

The results showed that increasing PPA dosage initially decreased the softening point of the modified emulsified asphalt, then increased it, while penetration and ductility first increased and then decreased. The study found that PPA modification improved high-temperature stability, fatigue properties, and low-temperature performance, with optimal compatibility achieved at a PPA dosage of 1.0%. However, excessive PPA dosage led to particle aggregation, weakening the modification effect. The study also noted that PPA underwent hydrolysis within the emulsified asphalt system, resulting in distinct modification mechanisms compared to base asphalt.

In conclusion, the research demonstrated that PPA could effectively enhance the performance of emulsified asphalt, particularly at a dosage of 1.0%. The study highlighted the importance of selecting an appropriate PPA content to optimize the properties of modified emulsified asphalt. Future research should focus on validating the long-term aging behavior and field performance of PPA-modified emulsified asphalt and further investigating the interaction mechanisms between PPA and emulsifiers to improve storage stability.

Pan, S., Liu, X., Li, X., Jia, J., & Yang, J. (2025). Feasibility of Polyphosphoric Acid in Emulsified Asphalt Modification: Emulsification Characteristics, Rheological Properties, and Modification Mechanism. Coatings, 15(4), 471. https://doi.org/10.3390/coatings15040471

2. Evaluation of the electrochemical interaction in the asphalt emulsion-aggregate system of cold mix asphalt through zeta potential and surface free energy analysis

In this article, researchers investigate the electrochemical interactions between asphalt emulsions and aggregates in cold mix asphalt. The study utilizes zeta potential and surface free energy analysis to understand these interactions, which play a key role in the performance and durability of CMA. By examining the electrical potential and interaction in the emulsion-aggregate system, this research aims to optimize the formulation and application of asphalt emulsions.

One of the key findings is the correlation between zeta potential, which measures the electrical potential at the boundary layer of particles in a suspension, and adhesion between asphalt emulsions and aggregates. Higher zeta potential values indicate better electrochemical compatibility, leading to improved bonding and stability of the asphalt mix. The study also highlights the role of surface free energy in determining the wettability and adhesion properties of the emulsion-aggregate system. Aggregates with higher surface free energy tend to perform better with asphalt emulsions, improving the performance of CMA.

The researchers then go on to explore the impact of different types of aggregates and emulsions on the electrochemical interaction. It was found that slow-setting cationic asphalt emulsions and certain Colombian aggregates, such as alluvial and quarried types, exhibit varying degrees of interaction based on their zeta potential and surface free energy characteristics. This variability highlights the importance of selecting appropriate materials to achieve optimal performance in cold mix asphalt applications.

In conclusion, the article provides valuable insights into the electrochemical mechanisms central to the interaction between asphalt emulsions and aggregates. By utilizing zeta potential and surface free energy analysis, the researchers suggest this could be used as a scientific basis for improving the formulation and application techniques of CMA.

Cuaran-Cuaran, Z. I., Castilla-Barbosa, M., Rincón, O., & Ocampo-Terreros, M. (2024). Evaluation of the electrochemical interaction in the asphalt emulsion-aggregate system of cold mix asphalt through zeta potential and surface free energy analysis. International Journal of Pavement Engineering, 25(1). https://doi.org/10.1080/10298436.2024.2361837

3. Maintenance mechanisms of rejuvenator-optimized asphalt emulsion in damaged porous asphalt mixture: Morphological, physicochemical, and rheological characterizations

In this article, authors were looking for a way to maintain porous asphalt mixtures that were aging and raveling faster than dense and gap graded pavements.  Previous studies had shown them that their typical surface treatments were only penetrating the pavement by 20mm.  In addition to improving penetration, they were looking for an emulsion composition that would also improve coating efficiency and faster diffusion into the mixture to improve bonding strength more quickly. 

Knowing that rejuvenators in emulsions have been successful in restoring aged binder characteristics, the authors decided to use one petroleum-based rejuvenator and one bio-based rejuvenator in their standard emulsion.  Both rejuvenators were emulsified separately at 60% by weight and then added back into the standard emulsion at 10% bwe for the petroleum based and 5% by weight for the bio-based rejuvenator.  The standard emulsion, containing 60% residue, served as the control.  For the mixtures, a polymer modified PG76-16 PAV aged binder was used.  The loose mixtures were aged at 135C for 8 hours and compacted.  Three freeze/thaw cycles were also applied to the compacted specimens to introduce cracking.  Cross sectional images of the mixtures were obtained using X-ray CT.  Binder was extracted at various cuts using dichlormethane for rheolgical and physiochemical properties.

Both the petroleum-based rejuvenators and the bio-based rejuvenator modified emulsions were found to penetrate the surface almost double the control emulsion as found by X-ray.  GPC testing confirmed these results.  FTIR analysis confirmed the penetration depth of the bio-based rejuvenator modified emulsion, but not the petroleum-based rejuvenator as the functional groups for both binder and oil were very similar.  G-R parameter and G* master curve analysis of the different binder layers showed that the modified emulsions were penetrating further and were rejuvenating the aged asphalt binder.  MSCR testing showed increased Jnr 3.2kPa for all three emulsions in layers 1-3, when compared to the aged asphalt binder.  %R, 3.2kPa was most affected by the petroleum based rejuvenator, but a reduction was seen across the board for all three emulsions. 

The authors recommended further work with additional slices of mix and varying asphalt aging levels in addition to monitoring cracking, rutting, water permeability, noise reduction and skid resistance outside of the lab. 

Yang, Bin, et al. “Maintenance mechanisms of rejuvenator-optimized asphalt emulsion in damaged porous asphalt mixture: Morphological, physicochemical, and rheological characterizations.” Construction and Building Materials, vol. 464, Feb. 2025, p. 140185, https://doi.org/10.1016/j.conbuildmat.2025.140185.

The 2025 season is off to a fast and promising start in many regions, with early activity indicating a strong year ahead for the asphalt emulsion industry. As agencies continue to look for ways to stretch their maintenance budgets, AEMA remains committed to providing education, resources, and opportunities for collaboration throughout the industry.

International Collaboration at ISAET ’24:

The 8th International Symposium on Asphalt Emulsion Technology (ISAET ’24), held in Washington, D.C., brought together global experts for three days of presentations and networking. Several AEMA members were among the 22 speakers, representing the association’s strong voice in advancing the science and application of asphalt emulsions.

Continued Engagement Through the IBEF Webinar:

Building on the success of the symposium, IBEF hosted a Technical Webinar in December that featured five of the most popular ISAET ’24 presentations. Among them was a contribution from AEMA Board Member Aaron Walker of Ingevity. The webinar saw significant engagement, with 230 registrants and 150 participants joining live to explore key technical topics.

New IBEF White Paper Now Available:

After 24 months of development and contributions from 14 industry professionals, IBEF has published a comprehensive new white paper. Now freely available to the public, the paper reflects a shared commitment to transparency and continued learning across the pavement preservation and asphalt emulsion sectors.

Regional Meetings and Upcoming Events:

The Southeastern Pavement Preservation Partnership (SEPPP) held its annual meeting in Richmond, Virginia, from March 18-20, bringing together stakeholders from across the region. Looking ahead, the Northeastern Pavement Preservation Partnership (NEPPP) is preparing for its next gathering in Somerset, New Jersey, from May 13–15.

PPRA Annual Meeting Recap:

More than 250 attendees came together in Rancho Mirage, California, for the 2025 Annual Meeting hosted by the AEMA-ARRA-ISSA (PPRA). The event offered an engaging mix of technical presentations, strategic discussions, and valuable networking opportunities that continue to shape the direction of our shared industry.

Share Your Updates with AEMA:

We’re always looking to spotlight the work and insights of our members. If you have industry news, event highlights, or updates from your company or region, we encourage you to share them. Please contact Morgan at morganb@cmservices.com or Ali at alim@cmservices.com to be featured in future editions of Industry Notes.

I trust this message finds you all in good health and happiness with yourselves and all your loved ones, and everyone is beginning to get that early season itch in anticipation of a great 2025!

I am honored to introduce myself as the new President of the Asphalt Emulsion Manufacturers Association (AEMA). It is a privilege to represent our dedicated member companies, and I am truly excited about the opportunities ahead for our industry and association over the next two years.

Just a few weeks ago, we held our Annual Meeting alongside our partners in PPRA, ISSA, and ARRA. It was a fantastic opportunity to connect with many of you, discuss key industry events and initiatives, and gain a deeper understanding of what our members truly value. During the AEMA Business Meeting, outgoing President Dan Koeninger outlined the association’s three-year strategic plan, setting the stage for continued progress and momentum. These discussions reinforced the importance of collaboration, innovation, and the role AEMA plays in driving our industry forward.

I would like to take a moment to sincerely thank Dan Koeninger of Barrett Industries, Greg Arntson of Albina Asphalt, and Xavier Guyot of COLAS for their outstanding dedication to AEMA, the Board of Directors, and the Asphalt Emulsion industry as a whole. As they transition into the next phase of their careers and exit the Board, we recognize the lasting impact of their tireless efforts. Their leadership and commitment have placed AEMA in a strong position for the future, ensuring that our association continues to thrive. On behalf of the entire association, I extend my deepest gratitude for their unwavering commitment and wish them all the best in their future endeavors.

One of the most exciting takeaways from our Annual Meeting was the enthusiasm and engagement we are seeing across the association. Our LEAP program participants continue to impress with their dedication, and I am especially encouraged by the energy throughout AEMA, with so many new members actively participating in key initiatives. This mix of fresh perspectives and veteran leadership is a powerful asset as we tackle the challenges and opportunities ahead.

As President, my focus is on enhancing membership value. A key priority will be strengthening our industry’s presence through RoadResource.org, a vital tool for education, training, and advocacy. Additionally, our Marketing Committee is doing tremendous work in promoting the benefits of emulsions and pavement preservation. We are also advancing important initiatives, including sustainability studies and the development of Environmental Product Declarations (EPDs) for emulsified asphalts, reinforcing the long-term value of our products in road construction and preservation.

I want to extend my sincere thanks to the AEMA Board of Directors and our membership for your trust and support. I am committed to representing your best interests and ensuring that AEMA continues to grow and deliver value. The momentum we have built together is strong, and I look forward to working alongside each of you to advance our industry.

Please feel free to reach out with any thoughts or ideas—I welcome the opportunity to connect.

Sincerely,

Matt Kennedy
President, Asphalt Emulsion Manufacturers Association 

I trust this message finds you all in good health and happiness with yourselves and all your loved ones, and everyone is beginning to get that early season itch in anticipation of a great 2025!

I am honored to introduce myself as the new President of the Asphalt Emulsion Manufacturers Association (AEMA). It is a privilege to represent our dedicated member companies, and I am truly excited about the opportunities ahead for our industry and association over the next two years.

Just a few weeks ago, we held our Annual Meeting alongside our partners in PPRA, ISSA, and ARRA. It was a fantastic opportunity to connect with many of you, discuss key industry events and initiatives, and gain a deeper understanding of what our members truly value. During the AEMA Business Meeting, outgoing President Dan Koeninger outlined the association’s three-year strategic plan, setting the stage for continued progress and momentum. These discussions reinforced the importance of collaboration, innovation, and the role AEMA plays in driving our industry forward.

I would like to take a moment to sincerely thank Dan Koeninger of Barrett Industries, Greg Arntson of Albina Asphalt, and Xavier Guyot of COLAS for their outstanding dedication to AEMA, the Board of Directors, and the Asphalt Emulsion industry as a whole. As they transition into the next phase of their careers and exit the Board, we recognize the lasting impact of their tireless efforts. Their leadership and commitment have placed AEMA in a strong position for the future, ensuring that our association continues to thrive. On behalf of the entire association, I extend my deepest gratitude for their unwavering commitment and wish them all the best in their future endeavors.

One of the most exciting takeaways from our Annual Meeting was the enthusiasm and engagement we are seeing across the association. Our LEAP program participants continue to impress with their dedication, and I am especially encouraged by the energy throughout AEMA, with so many new members actively participating in key initiatives. This mix of fresh perspectives and veteran leadership is a powerful asset as we tackle the challenges and opportunities ahead.

As President, my focus is on enhancing membership value. A key priority will be strengthening our industry’s presence through RoadResource.org, a vital tool for education, training, and advocacy. Additionally, our Marketing Committee is doing tremendous work in promoting the benefits of emulsions and pavement preservation. We are also advancing important initiatives, including sustainability studies and the development of Environmental Product Declarations (EPDs) for emulsified asphalts, reinforcing the long-term value of our products in road construction and preservation.

I want to extend my sincere thanks to the AEMA Board of Directors and our membership for your trust and support. I am committed to representing your best interests and ensuring that AEMA continues to grow and deliver value. The momentum we have built together is strong, and I look forward to working alongside each of you to advance our industry.

Please feel free to reach out with any thoughts or ideas—I welcome the opportunity to connect.

Sincerely,

Matt Kennedy
President, Asphalt Emulsion Manufacturers Association