PLUS Asphalt Pavement Density Profiling What We Now Know Pavement Design A Philosophy Considered The Award-Winning US460 Appomattox Bypass VIRGINIA ASPHALT A PUBL I CAT I ON OF THE V I RG IN IA ASPHALT ASSOC IAT I ON // FALL & WI NTER I SSUE 2022
VAASPHALT.ORG 05 Fall/Winter 2022 INSIDE THIS ISSUE Visit vaasphalt.org and follow us on Facebook for up-to-date industry and association news. Download the VAA News App and get timely information delivered to your cell phone. COLUMNS 06 PRESIDENT’S PERSPECTIVE 07 CHAIRMAN’S PERSPECTIVE DEPARTMENTS 34 VAA 2022 PARTNERS 35 AFFILIATE MEMBER SPOTLIGHT: RESURFACE INCORPORATED 35 AFFILIATE MEMBER SPOTLIGHT: THE KAUFFMAN GROUP INCORPORATED ON THE COVER The US460 Appomattox reconstruction project in VDOT's Lynchburg District. See more details on page 12. Photo courtesy of Boxley Materials. FEATURED ASPHALT PAVEMENT DENSITY PROFILING 08 Density profile systems are unlocking a new level of assessment for asphalt pavement performance. THE AWARD-WINNING US460 APPOMATTOX BYPASS 12 Repairing the Appomattox Bypass wins Virginia its first Perpetual Pavement Award: By Conversion. PAVEMENT DESIGN: A PHILOSPHY CONSIDERED 20 Looking to the future of pavement design might mean borrowing a few tricks from the past. WOMEN OF ASPHALT SPOTLIGHT 24 Get to know Angela Beyke: Assistant State Materials Engineer and one of the many many women professionals who are leaders in the asphalt industry. OCTOBERFEST 27 The VAA puts their spin on the German festival with a multi-day industry event. VIRGINIA INFRASTRUCTURE ACADEMY 30 Local leaders are innovating solutions in light of pandemic-induced spikes in unemployment and evolving industry needs. VECAT CONTINUES TO EVOLVE 32 The Virginia Education Center for Asphalt Technology unveils two specialty courses to address critical skill gaps. VIRGINIA ASPHALT A PUBLICATION OF THE VIRGINIA ASPHALT ASSOCIATION 7814 Carousel Lane, Suite 310 Richmond, VA 23294 Phone: (804) 288-3169 Email: email@example.com OFFICERS Chairman Chris Blevins Vice Chairman David White Secretary Bobby Hedrick Treasurer F. Marshall Luck, Jr. 1st Ex-Officio David Horton 2nd Ex-Officio Scott Claud Directors Ken Arthur; Tim Boone; David Branscome, Jr.; Sheila Cramer; Ed Dalrymple, Jr.; David Helmick; C.R. Langhorne; Buddy League; Ben Miller; Lonnie Minson; Jerry Short; Blair Williamson STAFF President Trenton M. Clark, PE Vice President David T. Lee, PE Director Mike C. Dudley Administration Caroline R. Fahed Member Relations Specialist Tigre J. Hammond DESIGN & ADVERTISING Advertising Sales: Ronnie Jacko Design & Layout: Jon Cannon For advertising opportunities and deadlines, contact LLM Publications at (503)445-2234 or firstname.lastname@example.org. ©2022 Virginia Asphalt Association All rights reserved. The contents of this publication may not be reproduced by any means, in whole or in part, without the prior written consent of the publisher. PUBLISHED NOVEMBER 2022
06 FALL /WINTER 2022 The opening line in Pastor Rick Warren’s Purpose Driven Life is, “It is not about you.” The book goes on to talk about purpose, why each person was put on this earth. So, have you ever stopped to consider what your purpose might be? Why were you put on this planet? Why do you work for a certain company or organization? I am convinced everything happens for a reason, and that there is no such thing as coincidence. If you don’t believe me, take a minute and look back over your life, or even a specific unforgettable moment. Is what happened strictly coincidence or part of a larger plan? As for me, becoming the President of the Virginia Asphalt Association (VAA) was never in the cards. When I was in high school, I planned to become an accountant, since a professional golfer would clearly never happen. It wasn’t until the summer after I graduated from high school that I switched to engineering—at the urging of my dad, a Virginia Tech Civil Engineering graduate. Dad told me, “Go to college and challenge yourself.” During my four years in Blacksburg, I was certainly challenged (try being the only engineer in an apartment with three business majors!). I was interested in building vertical structures, though much of my summer work experience was in site development, surveying and working in the Materials Division of the Northern Virginia District of the Virginia Department of Transportation (VDOT). By 1993, the economy sunk and finding jobs was tough. VDOT was one option, but they were in a hiring freeze. Finally, after sending out dozens of resumes, I got an interview with a pavement consulting firm in Maryland. Besides pushing a profilograph on I-66, picking up concrete cores from patching projects on I-66 and watching density testing, I knew nothing about pavement. But I got the job, and the rest is history. Looking back over nearly 30 years, how I got to this role was part of a bigger plan and purpose I could not have imagined. For us at VAA, our purpose is tied to our mission: “To promote the increased use and quality of asphalt pavement in Virginia.” The association’s purpose goes back to its founding by a group of asphalt contractors in 1952. Back then, promotion of the industry was essential. So was quality. Today, we look at the activities and actions of the association through the same lens by asking two simple questions. One, does this promote the increased use of asphalt? Two, does this activity improve quality? While not every activity affirmatively answers both questions, proposed or approved activities must answer at least one. This November, the VAA hosted a “Back to Basics” workshop with VDOT and the Virginia Transportation Research Council (VRTC), toward increasing the quality of asphalt pavement. The workshop focused on basic lab testing—maximum specific gravity, bulk specific gravity, aggregate gradation and AC content—because if these tests cannot be performed correctly, then all other calculations are meaningless. Presenters from the VAA, VTRC, VDOT and the National Center for Asphalt Technology (NCAT) all demonstrated testing under SUPERPAVE™ PRESIDENT’S PERSPECTIVE What Is Your Purpose? Trenton M. Clark, PE, President, Virginia Asphalt Association criteria for volumetric acceptance and balanced mix-design. This workshop was a great example of an unexpected, but necessary, item on the VAA 2022 business plan, and we were happy to put together the workshop and deliver on our purpose. We are continuing to fulfill both purposes of the association this winter, including, of course, the fourth Mid-Atlantic Asphalt Expo and Conference (MAAE), where exhibitors will showcase their products and services that will strengthen the asphalt industry. We always look forward to hosting this event, which promotes the positive and exceptional aspects of asphalt while emphasizing quality through technical sessions. Next, in 2023, the VAA will launch a new training and education program for plant technicians and mix designers through Germanna Community College (See “VECAT Continues to Evolve” on page 32). Over seven weeks, attendees will learn the basics of design and testing from industry experts, from proper procedures to analyzing results. It will be open to VAAmember employees, non-members, VDOT employees and students. In looking back, our purpose at the VAA has expanded, now encompassing a vision concerned with “the betterment of society.” What does this mean? Simply that we want to leave this earth better than we found it. Our actions and decisions have meaning and intentionality beyond ourselves. We will continue to push forward with initiatives that question the status quo— changing not for the sake of change, but to improve along the way. Our purpose is clear. I hope yours is too. Stay safe!
VAASPHALT.ORG 07 In our industry, we struggle to attract new talent because the hours are often long, days are hot, and the weather wreaks havoc on our efforts, all followed by winter layoffs. On top of that, the work we do is inherently dangerous. Our teams deal with distracted drivers who pay little to no attention to the traffic control measures we install. That is why it is of the utmost importance that we provide our people— our most valuable assets—with the safest environment possible to ensure everyone goes home at the end of each shift. When I think about safety, I think back to my younger days. As a child, I was blessed with parents who instilled in me a sense of pride in all my endeavors. Their lessons included doing things right the first time and being safe along the way. This pride has served me well throughout my career, and I believe it significantly impacts how I face each day at work. Over the years, I have seen that same sense of pride in employees throughout our industry. When talking with different crews, it is easy to see how committed they are to having each other’s backs. Their commitment is visible when the “seasoned vet” demonstrates the proper use of the shovel to spread asphalt to a new team member, and in the reminder that PPE is their personal protective equipment, so use it! These simple actions show care for safety and work done well, and they build cohesion until the crew begins acting as a successful unit. W-L Construction & Paving has implemented several proactive initiatives in regards to employee engagement, with the understanding that each employee is not only responsible for their own safety but also the safety of their team. One management- led initiative is “See, Stop, Do” Day. Each month on this day, management spends the day in the field with our crews discussing essential safety topics, one of the most important being “if you see something amiss, stop and do something about it.” It is a time for employees to engage in conversation with top management, asking questions, lifting concerns and sharing personal stories. It is also an opportunity for leaders to address any safety concerns, reiterate the importance of safe practices, and get to know employees personally. It sends a clear message that safety is the #1 priority. All of our actions have consequences, even our choice to get up and go to work in the morning. Most will say the reason they do any job is for the money; but, when you dig deeper, there’s always more to it. For me, I love the challenge and the opportunity to make a difference each day. As a son, I want to make my parents proud. As CHAIRMAN’S PERSPECTIVE Be the Difference Chris Blevins, PE, Vice President, W-L Construction & Paving, Inc. a husband, I want to make my wife proud. As a father, I want to make my kids proud. As a grandfather… you get the picture. I leave you with this: think of something at work this week that made you happy. If you are honest, I bet money was not the first thing that popped into your mind! While you may work for your salary, it is likely not the primary thing that makes you happy. It is the random thank you from a co-worker, your boss acknowledging your hard work, or the satisfaction of a job well done. I challenge you to hold on to that thought and use it to fuel your commitment to making a difference in your workgroup. Be the reason that all go home safely at the end of each day. There are a number of reasons our working environment is dangerous, but even one person can make a difference by doing things safely and with pride. Make safety your #1 priority. All of our actions have consequences, even our choice to get up and go to work in the morning. Most will say the reason they do any job is for the money; but, when you dig deeper, there's always more to it. Chris and Jennifer at Dallas Cowboys home field
Brian Diefenderfer, PhD, PE, Principal Research Scientist, VTRC Hari Nair, PhD, PE, Associate Principal Research Scientist, VTRC Figure 1. Example of a DPS device used on asphalt pavement overlay projects in 2021 Asphalt Pavement Density Profiling A l D What We NowKnow 08 FALL /WINTER 2022
VAASPHALT.ORG 09 Achieving adequate and uniform density is critical to obtaining the desired performance of a newly placed asphalt pavement layer. The mix compaction process is critical, as the aggregate particles are reoriented and the volume of air within the mixture is reduced, and many studies have shown that inadequate compaction results in a decreased durability of the asphalt mixture. The degree of compaction is usually expressed as a percentage of a reference density. However, the reference density may be a theoretical maximum density (the density if all the air voids were removed), the density of a field-produced control strip or a laboratory value derived during mix design. Current tests for quality control and acceptance of asphalt mixtures placed on Virginia Department of Transportation (VDOT) projects relies on nuclear density gauge testing and collection and testing of sawn plugs, respectively. Neither of these processes are optimal. Use of the nuclear density gauge requires stringent use and storage requirements due to the Cesium source material. Collecting and testing sawn plugs is a destructive and time-consuming process. In addition, these tests only assess a small portion of the pavement mat (about 0.003%). Instead, the use of a density profiling system (DPS) could allow more rapid assessment over a larger sampling area and allow contractors to have real-time feedback of achieved density during the paving operation. A DPS device operates by correlating a measured material property to pavement density. In its current form, DPS uses ground penetrating radar (GPR) technology, measuring the dielectric constant of the pavement surface. The dielectric constant of a material—or the relative permittivity—represents the ratio of the electrical permittivity of a material to the permittivity of a vacuum. For use in pavement surveys, GPR operates by transmitting pulsed electromagnetic energy into a pavement and collecting the reflected energy. A portion of the incident pulses are reflected at boundaries between two materials with differing dielectric constant values. Specifically, in the case of measuring the surface layer of pavements, air and the pavement are the two boundary materials. The dielectric constant of the pavement surface layer is calculated based on the ratio of the amplitude of the signal reflected at the air-to-pavement interface to the incident amplitude, obtained by measuring the reflection from a metal plate. Figure 1 shows a DPS device that was used by the Virginia Transportation Research Council (VTRC) on four asphalt paving projects during the 2021 construction season. The DPS device, manufactured by Geophysical Survey Systems, Inc. (GSSI), consists of three GPR antennas operating at a central frequency of 2.0 GHz, a data recording and processing computer, and a global positioning system (GPS) sensor mounted on a push cart. The four projects assessed in 2021 were located in the Culpeper, Lynchburg, Richmond and Northern Virginia districts. The projects included an asphalt overlay placed over either a milled or existing asphalt pavement surface. Testing was conducted to evaluate the DPS technology first by determining the correlation between the field-measured dielectric constant and the lab-measured density from cores for different asphalt pavement mixtures, and then by assessing the density longitudinally and transversely. Testing at each project was completed by scanning an approximately 500-foot section from which nine calibration cores were collected. Next, the DPS device was used to scan selected portions of each project site. Within each lane, the DPS was operated in Percent Maximum Density Dielectric Constant 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 100 98 96 94 92 90 88 86 84 82 80 y=9.8978x + 41.73 R2 = 0.9612 Figure 2. Correlation between dielectric constant and percent maximum density for one project two passes, with three antenna passes covering the left and right side of each lane, for a total of six antenna passes per lane. After field testing, the density (expressed as a percentage of the theoretical maximum) was measured for each calibration core. These data were used to establish a correlation between the DPS device output and the pavement density. Using this correlation, the density was assessed for the scanned areas of each project. Results: Density Correlation and Continuous Pavement Density The dielectric properties of an asphalt mixture are dependent on the dielectric properties of the mixture components that can vary from project to project. Calibration cores were collected from each project, covering a range of dielectric constant values, to establish a relationship between percent maximum density and dielectric values. The study found that the dielectric constant values from the DPS were well correlated with the percent maximum density (with R2 values ranging from 0.82 to 0.98). Figure 2 shows an example of this relationship. The results of testing using the DPS were evaluated with respect to the longitudinal and transverse directions. For each project, relatively lower density values were found along certain longitudinal joints and unsupported edges. As expected, lower density variability was found on primary routes while higher density variability was found on pavements located in subdivisions. ASPHALT PAVEMENT DENSITY PROFILING continues on page 10 △
10 FALL /WINTER 2022 Figure 3 shows an example of the density results for part of one project. The numbers 1, 3, 4 and 6 correspond to four of the six antenna passes along the lane. Passes 1 and 3 were along the left edge and left-center of the lane while Passes 4 and 6 were along the right-center and right edge of the lane. This figure shows that the density is fairly uniform between Passes 1, 3 and 4 but the density is much lower for Pass 6. Pass 6 was collected close to an unconfined edge. The figure also shows local density minimums at distances of approximately 860, 960, 1050, 1175 and 1260 feet. These are the approximate locations where trucks delivering asphalt to the paver were switched. Figure 4 shows another way to view the density profile data. From this figure, it can be seen that the 50th percentile density for Passes 1, 3, 4 and 6 is approximately 93.7%, 93.4%, 92.8% and 87.6%, respectively. If specifications required a minimum of 92.5% density, the percent conforming for Passes 1, 3, 4 and 6 is approximately 79.4%, 79.2%, 62.0% and 0.0%, respectively. Conclusions and Future Testing The study concluded that the DPS device is a promising tool for continuous density assessment. Additional testing is recommended to study additional mixture types and to determine a process to reduce the need for field-obtained calibration cores. The VTRC project team continues to collect data using the DPS on projects during the 2022 construction season. In addition to gathering data on additional mixture types (including intermediate and base mixtures), the research team is investigating the use of a lab-based DPS component that could eliminate or reduce the need for calibration cores collected from the field. The lab-based DPS consists of a single GPR antenna and data collection computer and is designed to facilitate testing of gyratory pills that could be fabricated during the mix design process or the day of paving. It is anticipated that gyratory pills, having a range of density values, could be produced and tested in the laboratory prior to paving. The study of these changes and other topics is underway as part of a VTRC study and also through a transportation pooled fund study (TPF 5(443)) led by the Minnesota Department of Transportation. References Brown, E. R. Basics of Longitudinal Joint Construction. Transportation Research Circular E-C105. Factors Affecting Compaction of Asphalt Pavements. Transportation Research Board, 86-95, 2006. Hughes, C. S. Compaction of Asphalt Pavement. NCHRP Synthesis of Highway Practice 152, National Cooperative Highway Research Program, Transportation Research Board, Washington, D.C. 1989. Maupin, G. W. Preliminary Field Investigation of Intelligent Compaction of Hot-Mix Asphalt. VTRC-08-R7, Virginia Department of Transportation, 2007. Saarenketo, T., 1997. Using Ground-Penetrating Radar and Dielectric Probe Measurements in Pavement Density Quality Control. Transportation Research Record, No. 1575, pp. 34-41. Scherocman, J. A. Compacting Hot Mix Asphalt Pavements: Part 1. Roads and Bridges, December 28, 2000. Sebesta, S. and T. Scullion, 2007. Infrared Imaging and Ground-Penetrating Radar as Quality Assurance Tools for Hot Mix Paving in Texas. Journal of the Association of Asphalt Paving Technologists, Vol. 76, pp. 1-40. Tran, N., P. Turner, J. Shambley. Enhanced compaction to improve durability and extend pavement service life: a literature review, NCAT Report 16-02R, 2016. Percent Maximum Density Distance, ft 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 100 98 96 94 92 90 88 86 84 82 80 1 4 3 6 Figure 3. Percent maximum density with respect to project distance for four antenna passes Cumulative Percentage Percent Maximum Density 80 82 84 86 88 90 92 94 96 98 100 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1 4 3 6 Figure 4. Cumulative distribution of percent maximum density for data shown in Figure 3 △ continued from page 09 ASPHALT PAVEMENT DENSITY PROFILING
12 FALL /WINTER 2022 THE AWARDWINNING US460 APPOMATTOX BYPASS
VAASPHALT.ORG 13 Perp P e a tu vi a n l g THE AWARD-WINNING US460 APPOMATTOX BYPASS continues on page 14 △ ASTUDY IN Kenneth W. Arthur, Director of Asphalt Plants and Development, Boxley Materials David T. Lee, PE, Vice President, Virginia Asphalt Association The Appomattox Bypass was constructed as a nine-inch jointed-concrete pavement in the early 1990’s, designed to last forty years. However, after twenty years of service the ride began to significantly deteriorate as slabs began to rock under traffic. Local engineers recognized that the dowels between slabs were not transferring loads as expected. As joints opened, water began to impact the substructure, consisting of a #57 drainage layer and cement-stabilized soil. Once noticed, the VDOT spent the next decade performing significant repairs to the pavement, including concrete patching and slab-jacking to improve the ride. In March 2017, VDOT requested bids for a long-term solution to repair the Appomattox Bypass. The plan would require rubblization of the concrete and overlaying the entire section with asphalt pavement, including over five lane-miles of mainline in the eastbound lanes with a three foot inside shoulder and ten foot outside shoulder. Boxley Materials Company was the successful bidder with a 5.3 million dollar project plan, executed from June through October 2018. 0 The Virginia Department of Transportation (VDOT) was one of six departments and agencies to win the first inaugural Perpetual Pavement Award: By Conversion, granted by the Asphalt Pavement Alliance to recognize noteworthy asphalt pavement design, construction and value in the U.S. The award was in commendation of the rubblization of a section of US Route 460 known as the “Appomattox Bypass,” spanning the historic Lynchburg district of Central Virginia. The Appomattox Bypass is a high-volume primary highway, used by approximately 3,500 vehicles per day, on a wellknown east-west route stretching from Virginia Beach to the West Virginia State line.
14 FALL /WINTER 2022 Boxley Materials Company of Blue Ridge, Virginia, was founded in 1908 as an aggregate and ballast supplier for the booming railroad industry constructing mainline rails across the Commonwealth. Now a part of the East Region of the Summit Materials family of companies, Boxley’s bid for the project included serving as the general contractor and providing the project's asphalt pavement, stone base and paving installation services. In a 2018 interview with AsphaltPro magazine, Boxley Chief Estimator Eddie Blount remarked about the unique partnership opportunity the project provided his company. “Because it was a VDOT-designed project, the Department had a clear understanding of what they wanted as a finished project. There were plenty of opportunities to partner through the learning curve because the process was unique to our area. VDOT afforded us flexibility on executing the work and was a great partner on the project.” The Boxley team faced the challenge of managing traffic during construction by shifting vehicles to a single lane, comprising the travel lane and ten-foot shoulder. As the intermediate lift was completed, traffic was switched and the rubblization process was repeated on the passing lane and inside shoulder. Brian Peiklik, Boxley Project Manager, shared with AsphaltPro magazine that the benefit of this method “was that it gave us more room to work and made things safer for the traveling public.” Other challenges included significant undercut, underdrain removal and reinstallation and adjustment of planned traffic detours to accommodate motorists. There were also nuances of working with concrete that Boxley had not encountered before this project, particularly with line eradication. Before traffic could be switched, a Boxley subcontractor had to eradicate a thermoplastic longline from the concrete. This proved extremely hard on the teeth of the long-line pavement grinder, and consequently much of the marking was removed with the cutting edge of the motor-grader. Boxley subcontracted the rubblization operation to Antigo Construction from Wisconsin. They then used a Badger Breaker truck-mounted rubblizing machine to break the existing concrete into hand-sized pieces, and a Bomag Z-grid patterned steel wheel roller to crush the materials closer to the size of a #57 with a single pass. Their roller pattern included two more passes with a Bomag steel wheel roller and two additional passes from a CAT pneumatic roller for a total of five passes. To achieve VDOT’s gradation specification, they adjusted the roller pattern for in-place rubblized material by depth. Paving on the newly rubblized concrete was similar to paving on a porous asphalt layer of loose aggregate. Boxley staggered the dump trucks and shuttle buggy where possible on the non-rubblized pavement, so that only the paver was on the rubblized material. Boxley had to operate differently when the entire paving train had to be placed on rubblized material. This required additional labor in front of the paver and shuttle buggy to address areas impacted by the equipment and incoming trucks. Dump-truck drivers had to be intentional about how quickly they accelerated and decelerated to limit their impact on the surface. Boxley used a Roadtec 2500A shuttle buggy and a Roadtec 190E paver for laydown operations; and on the ramps, where there were steeper grades, Boxley utilized a Propave 110RT track paver to better distribute the weight for installation. One of the project’s highlights was the use of a high-binder asphalt base design directly on the rubblized concrete. On the mainline, this was a four-inch lift of BM-25.0D+0.8 with an asphalt content of 5.2%. To ensure rutting would not occur under traffic during THE AWARD-WINNING US460 APPOMATTOX BYPASS △ continued from page 13 continues on page 16 △
VAASPHALT.ORG 15 THE AWARD-WINNING US460 APPOMATTOX BYPASS
16 FALL /WINTER 2022 △ continued from page 14 THE AWARD-WINNING US460 APPOMATTOX BYPASS construction, VDOT Lynchburg District’s Materials Division performed rut testing on the same high-binder base design from a previous design-build project. The Department was confident after the rut data returned positive. Asphalt Quality Control Manager Andre Royal mentioned how unusual the high-binder base felt under foot after compaction, saying the technician and he were concerned about walking on the mat after compaction on the first day of production. “It still felt soft underfoot, but after it cooled, it was as sturdy as can be. I loved how easy it was to achieve great density.” There were fourteen cores cut on the project from the BM-25.0D+0.8 that averaged 97.6% density in the three-inch lift sections and 96.4% density in the four-inch lift sections. The heightened field densities and high liquid content made for an excellent application, arguably much less prone to stripping than a conventional BM-25.0A base mix. The BM-25.0D+0.8 caused no significant change to production, laydown, or testing operations. The mainline pavement was paved in three lifts, with four-inch BM-25.0D+0.8, two-inch IM-19.0D and two-inch SM-12.5D. The highway section’s three bridges also impacted pavement design. VDOT specified performing full-depth removal and replacement to maintain vertical clearance in each location. This pavement structure was composed of a base layer of nine-inch 21-A stone base and seven-inch BM-25.0D+0.8. In total, there were eleven inches of asphalt in the full-depth replacement locations placed in four lifts: four-inch BM-25.0D+0.8, three-inch BM-25.0D+0.8, two-inch IM-19.0D and two-inch SM-12.5D. When Boxley personnel rode the first lift of BM-25.0D+0.8 upon completing a long pull, they were surprised. Even after
VAASPHALT.ORG 17 THE AWARD-WINNING US460 APPOMATTOX BYPASS incorporating a shuttle buggy to achieve the smoothest ride possible on the first lift, there was significant movement of the mat on the rubblized material. While this did not negatively impact density, it significantly impacted ride. Boxley Paving Superintendent Jerome Christian was confident his team could achieve low International Roughness Index (IRI) numbers with two lifts remaining to complete—and they did just that. The ride was significantly improved after the IM-19.0D installation and set up well for the final lift of SM-12.5D. Christian’s crew achieved final average IRI numbers of 60.4 and 58.5 on the two 2.6mile lanes, earning a rideability bonus for both. In total, Boxley shipped and laid 33,000 tons of warm-mix asphalt for the project. This included roughly 17,000 tons of BM-25.0D+0.8, 8,000 tons of IM-19.0D and 7,900 tons of SM-12.5D. Boxley transported all of this material over fifteen miles to the site from their Lynchburg plant, near Liberty University. The Appomattox Bypass project on Route 460 would go on to win the VDOT Lynchburg District Construction Paving Award and be named the VDOT Statewide Construction runner-up for 2017. The hard work and collaboration between VDOT and Boxley personnel was a testament to the industry. As Summit Materials’ Vice President of Asphalt and Construction Charles Craddock stated, “The uniqueness of this project made it enjoyable. We encountered some unusual circumstances that provided opportunities to partner with VDOT and our subcontractors to deliver an excellent project on time and within budget.” Not only has this project earned VDOT their first Perpetual Paving Award: By Conversion, but it will also serve the community for decades to come.
18 FALL /WINTER 2022
VAASPHALT.ORG 19 Ronnie Jacko email@example.com | 503.445.2234
20 FALL /WINTER 2022 PAVEMENT DESIGN: A CONSIDERED Trenton M. Clark, PE, President, Virginia Asphalt Association Before we begin, I want to make a few things clear. First, this review is based on my experience and opinion, and I do not speak for the Virginia Asphalt Association. Secondly, though this has been my career since 1993, I’ve never formally studied Pavement Design. There was a class offered my senior year at Virginia Tech, and would have made for a helpful elective, but the professor was the new guy—Dr. Imad Al-Qadi from Penn State—and I heard he was tough. So, like a fool, I took Finite Element Methods instead. Live and learn. (On a personal note, I consider Imad a dear friend and mentor in this industry, and you’ll see him mentioned numerous times throughout the following pages.) It was not until the early 2000s that the late Dr. Lynne Irwin took the time to teach me mechanistic-empirical pavement design. Once a week over a series of months, he gave virtual lectures, homework and discussion to help me understand M-E pavement design. Philosophy
VAASPHALT.ORG 21 So, is pavement design really that complicated, or is it job security for niche engineers like me? The answers are simple: yes and yes. History of Pavement Design Before we can understand the complexities of pavement design, we need to understand how it evolved. For the sake of this article, I plan to cover the quick history lesson; but, I’m no Dr. Al-Qadi, so I will recommend anyone interested in a more detailed history of pavements to visit Pavement Interactive (pavementinteractive.org). Most people have heard about the ancient Roman roads. Before Rome, however, there were roads built by the Mesopotamians and peoples on the Indian subcontinent some 4,000 years ago. These roads were constructed from pavement composed of thick layers of stone, then covered with smaller rocks to lock the materials into place. The pavement’s thickness and the stones’ size protected the natural subgrades and drainage and storage capacity for water. The final surface had to be smooth enough so that large armies could quickly march and drive their chariots across their empire. To my knowledge, these roads were not designed using layered elastic theory or finite elements but they shared our commitment to empirical study: trial, error and observation. Once they found out what worked, the method was replicated over and over, often shared across cultures. Fast forward a few thousand years. While the Roman roads were still being used in the 18th and 19th centuries, the populations of Europe and the United States were growing and expanding outwards, requiring more roads. The roads built by the Romans were costly and labor intensive, so while they worked and persevered over the centuries, that was not the road-building approach used by modern builders. Too many roads were needed for an expanding society, and too quickly. The pavement produced was designed simply to keep travelers out of the mud. Enter British surveyor Thomas Telford and Scottish engineer John McAdam. Both took what they observed from the Roman roads and their experiences with contemporary pavements to make design modifications. Telford designed roads on a flat subgrade with three layers of stone, for a maximum thickness of approximately eighteen inches (450 mm). Drainage was provided on the surface, but this approach allowed the subgrade to be wet. Following Telford was the Macadam method, popularized by John McAdam. He noted two issues with the Telford approach. One, that most surface stones were round and not angular, allowing them to be easily displaced by traffic. Therefore, he proposed replacing the round stones with angular rocks to help lock the surface. Two, the flat subgrade needed to be sloped to aid drainage. His approach still used three layers of stone with the top layer mixed with fines and compacted, but the total thickness was reduced to approximately ten inches (250 mm). The design refined by McAdam was used for decades. By the mid-to-late 1800s, tar and asphalt materials were mixed with aggregates to form a more stable and durable pavement. Macadam projects were then installed in Nottingham, England; Nashville, Tennessee and Washington, D.C. In the 1900s, various locations in the United States had their own set pavement designs. The materials used for the pavements were based on local specifications, and the layer thicknesses were based on experience and performance. It was not until the middle of the 20th century that flexible pavement thickness equations were developed in order to methodize design. Much like the original American Association of State Highway and Transportation Official (AASHTO) nomographs developed from their well-known Road Test in Ottawa, Illinois, these equations were empirically based. In other words, build it and see what happens. Since the AASHTO Road Test, engineers and researchers have been refining the design process. Many large oil companies had pavement research offices like Royal Dutch Shell and Chevron for asphalt pavements. They and entities such as the Asphalt Institute developed Interstate 81 after 40 years of service Just a little too thick continues on page 22 △ PAVEMENT DESIGN: A PHILOSOPHY CONSIDERED
22 FALL /WINTER 2022 △ continued from page 21 design processes following a combination of mechanistic (engineering properties and responses due to loads) and empirical (measured road performance) analyses. These led to the rise of mechanistic-empirical (ME) pavement design procedures. Eventually, AASHTO took up the effort to refine the existing design process and develop the AASHTO ME Design Guide used by several state departments of transportation today. While AASHTO was working on their guide, the National Asphalt Pavement Association contracted with Dr. David Newcomb at the University of Minnesota to develop a mechanistic design approach. With the assistance of Dr. David Timm, they developed the PerRoad program for perpetual pavement design. Since then, Dr. Timmhas refined the perpetual pavement design approach fromusing a single limiting strain value to the distribution of strains, based on his research at the National Center for Asphalt Technology (NCAT) Test Track in Auburn, Alabama. In less than a century, we have gone from an experience- based pavement design approach to highly sophisticated, computer-required, data-intensive design processes. Pavement DesignToday, Practically Speaking I have been in the pavement engineering field for nearly thirty years. I have been involved with the Transportation Research Board pavement committees. I have served on a number of other national and state pavement research committees. I was a part of the AASHTO task force that sunsetted the DARWin pavement design tool and wrote the initial PaveME application requirements. Yet, even I have been guilty of making pavement design more complicated than it needs to be. That changed in the 2000s, when Dr. Al-Qadi and I were both involved in a study that would later be called “Field Investigations of High Performance Pavements in Virginia” (VTRC 05-CR9), during which we observed and tested Virginia pavements for performance. By determining the common characteristics of well-performing pavement, we wanted to establish a premium pavement design for use on future VDOT projects. After evaluating eighteen sections (flexible, rigid and composite), we made a few key observations. First, long-term performance is tied to subgrade and sub-base. Most well-performing sections had a firm, stabilized subgrade and aggregate base layer. Two, these pavements were not experiencing issues with sub- surface drainage and loss of strength. Three, the flexible pavements’ thickness ranged from approximately eight to fifteen inches. Where pavement distress was present, it manifested from the top down or due to a mid-layer material (i.e., stripping) or construction (i.e., no bond) issues. Bottom-up fatigue was not believed to be a primary failure mechanism. While a follow-up project was recommended, it was never commissioned. However, over the next five years, I was involved in numerous pavement evaluations across Virginia to determine causes of failure and recommend pavement rehabilitation designs. The lessons learned from the 2005 project were verified and validated time and time again: in most cases, pavements too thin with inadequate subgrade/subbase support failed from the bottom up; and thicker pavements and those with a firm foundation failed from the top-down or mid-layer up. Nearly all these pavements were designed following VDOT’s procedure based on the AASHTO Road Test. I guess the Mesopotamians and Romans knew what they were doing when it came to well-performing pavements. Just a little too thin PAVEMENT DESIGN: A PHILOSOPHY CONSIDERED
VAASPHALT.ORG 23 Looking to the Future of Pavement Design Today, much of the pavement engineering community focuses on complex design approaches developed through research projects. This is valid and crucial for specific U.S. and world applications: we are seeing new aircraft wheel gear configurations emerging, super heavy loads at port facilities, and special loadings on highways becoming more and more common. Will closely-spaced truck platooning with super single tires and no lateral wander change the overall thickness? Today’s pavement design procedures rely heavily on modeling and assumptions to predict performance and required thickness. The PaveME procedure developed by AASHTO uses layered-elastic theory combined with past climate data and distress modeling to predict future performance. The pavement thickness and materials properties can be modified until performance criteria are satisfied. Yet, the local, regional and climate data of the past cannot predict the future climate. Current rainfall, drought, heat and cold events are more extreme than what has been recorded in hundreds or thousands of years. The modeling of pavement distresses such as cracking and ride quality have a wide coefficient of variation and low R-squared values. While the trends of the data plots may make sense, their accuracy is low. I’ll also add that, as a person who moved from a blackbox desk engineer doing pavement designs to one who got out and observed the construction and paving processes, accuracy to the nearest tenth of an inch is meaningless when tolerances to the half-inch or full inch are allowed for roadway construction specifications. Realistically, the vast majority of new and rehabilitated pavements will not be designed by the pavement engineering community. This responsibility will fall to local public works officials or design consultants. From experience and observation, they may implement what works in the local area even though the accepted pavement design method does not confirm its long-term performance. We go back to our original question: build based on design, or based on what works? The answer to future pavement performance is simple: a design catalog generated through mechanistic principles and validated through local experience. The materials selected will differ across a state or even region, but the approach would remain the same. Generating the designs would be as simple as performing analysis with a range of subgrade and sub-base layer strengths and performing an analysis, since we now know that the key to long-term performance does not lie with the overall thickness as much as with the paving materials selection. From Virginia’s research project in the early 2000s to subsequent field investigations, we have found the “sweet spot” for flexible pavement is between eight and fourteen inches of asphalt concrete on a solid sub-base foundation and adequate drainage depending on truck traffic levels. At thicknesses below eight inches, the risk of bottom-up failure increases. At thicknesses over fourteen inches, tax-payer dollars are being spent without a big return on investment. In that range, adding an inch of asphalt doubles the structural life of a pavement, according to the work done by Jim Huddleston and other engineers. The research documented by NCAT in their report 15-05R indicates a worst-case scenario of 15.5 inches of total asphalt on a weak base and subgrade layer. Most high-volume pavements in Virginia would not be constructed on a subgrade of 5,000 psi. Time, effort and money to calculate a thickness to the nearest tenth or quarter of an inch miss the bigger picture. We often miss the little things that turn out to be the big things. With pavement design and performance, we can’t take materials or construction techniques for granted. Over thousands of years, we have learned what works, and that should remain our basis of pavement design. Interstate 66 cracking due to mid-layer striping PAVEMENT DESIGN: A PHILOSOPHY CONSIDERED
24 FALL /WINTER 2022 Women of Asphalt Spotlight: ANGELA BEYKE, PE Tigre Hammond, Member Relations Specialist, Virginia Asphalt Association Angela Beyke, PE, Assistant State Materials Engineer, Virginia Department of Transportation A generation or two ago, most women wouldn’t think to look to the asphalt industry for a job, let alone a long-term career. There were few resources and supports for women when entering the industry. As time has past, women have gained greater awareness and unlocked opportunities in the industry, paving the way for upcoming generations to find their footing in a male-dominated industry. This progression is in part due to the efforts of groups like Women of Asphalt, a national coalition founded in 2017 to support women in seeking careers throughout the asphalt industry through mentoring, education and advocacy. Angela Beyke’s story is one that reaches back before such programs existed, and offers further proof of how women have fought for the roles, impact and legacy they hold today. Angela Beyke, PE: Virginia Department of Transportation’s New Assistant State Materials Engineer If someone would have told me fifteen years ago that I would make a career out of materials and asphalt, I would have told them they were lying. Boy, am I glad I was wrong. Growing up, I never really knew what I wanted to do as a career. I had ideas—lawyer, teacher, doctor—but they never stuck. All I knew was that I was good at math and science and wanted to do something with it. Thankfully, I was given my first taste of engineering in high school, and I was instantly hooked. I took engineering courses and tried to narrow down my focus, thinking I had it all figured out. During these classes, I had my first experience being in the minority, since most of the classes had a high male-to-female ratio. One particular group project my senior year was an eye-opener for me. I felt like my opinions and thoughts were ignored and I became very discouraged. Then, I received a piece of advice that I’ve carried with me throughout my career from a teacher I reached out to for help. He listened to how I was feeling and asked if I was going to speak up louder or back down. He said, “You can believe in how people make you feel, back down, and show them they’re right. Or, you can be strong and show them they’re wrong.” Not only did this teacher keep me from walking away from engineering all together, but he also became a voice in the back of my head during hard situations. I enrolled in West Virginia University (WVU) with a plan to major in Mining and Civil Engineering, with a particular interest in remediation of old mining sites. After the first few weeks of classes, I dialed into Civil Engineering. I really felt like I found my niche in the transportation, materials, and concrete and asphalt courses. The civil engineering program had a high male-to-female ratio, as would be expected, but I was able to forge some close-knit relationships with others through my classes, the Society of Women Engineers (SWE), and the American Society of Engineers. Along with my degree, one lesson I walked away fromWVU with was how important and how far networking experiences can take you. During the summer between my junior and senior year, I was fortunate to intern for the Virginia Department of Transportation (VDOT) in the pavement group of the Maintenance Division. Upon graduation, I returned to VDOT full time through the Core Development Program, a competitive track for new VDOT employees allowing rotations between divisions. I began in Materials- Pavement Design, learning the ins and outs of asphalt and concrete pavement, Non-Destructive Testing (NDT) and pavement investigations. Within my first year, I observed operations of an asphalt plant, was invited into the field on paving operations and performed field investigations based on premature failures. It was exciting, and every day brought something new. Within ten months, I moved to VDOT’s Asphalt Program and learned as much as possible. I was in the lab learning the tests,
VAASPHALT.ORG 25 WOMEN OF ASPHALT SPOTLIGHT studying specifications and utilizing every resource to which I had access. I eventually began teaching certification schools and writing the same specifications I was studying months previously. It was there that my interactions outside VDOT began to grow. I met many people involved in asphalt construction, from liquid suppliers and paving crews, to quality control personnel and industry reps. Each group brought something different to the conversation, and I credit them for helping me meet my successes along the way. Over the course of my seven years within the Asphalt Program, I’ve enjoyed being a part of day-to-day tasks, research projects, implementation of new initiatives and programs, large scale projects, disputes and resolutions, presentations and personnel management. Then, in 2018, I transitioned from asphalt to concrete. I became proficient in another material, met a different group of industry and built some new relationships. Earlier this year, I made the move back to my roots and am now the Assistant State Materials Engineer, overseeing VDOT’s Asphalt and Pavement as well as Design programs. One of my first major tasks is continuing to lead Virginia’s implementation of BalancedMix Design. It is a demanding role, but one that I look forward to every single day. Throughout my career, I have dealt with positives and negatives of being a woman in a male-dominated field. I have had to not only grow technically and professionally, but also have undergone personal development—and I continue to do so. Finding a strong voice and believing in myself was essential to my journey to get to the position I am in now. Surrounding myself with mentors, those who believe in me and those who challenge me, not only helped teach me what I know but also allowed me to grow in confidence. One thing close to my heart is sharing my experiences with other females who are interested in the science and engineering fields. I am currently involved in local chapters of Women of Asphalt and SWE, and I am an advisor to a SWENext club at a local high school, counseling girls who are planning a future in engineering. It is important to me to share the experiences of women in the field— the opportunities we have had and the challenges we have encountered—and be able to answer any questions they may have. If I have a part in bringing just one female into this field and keeping her long-term, my experiences have been worth it. The driving force behind my growth, development and success in my career are my kids. I want my son to grow up seeing strong women pursue their goals. I also want my daughter to know she can do anything she wants to, as long as she puts her mind and heart into it and works hard. Being a woman in a male-dominated field and starting a family is anything but easy, but I’ve done it and am a stronger, more successful woman and engineer because of it. I received a piece of advice that I’ve carried with me throughout my career from a teacher I reached out to for help. He said, “You can believe in how people make you feel, back down, and show them they’re right. Or, you can be strong and show them they’re wrong.”vaasphalt.org