PLUS Towards Sustainable Paving Virginia's Initial Efforts to Incorporate Recycled Plastic Waste into Asphalt Mixtures What if BMD is a Failure? There Are Many Different Measures of Success A Ribbon of Black: Paving the CBBT VIRGINIA ASPHALT A PUBL I CAT I ON OF THE V I RG IN IA ASPHALT ASSOC IAT I ON // SPR I NG & SUMMER I SSUE 2022
VAASPHALT.ORG 05 Spring/Summer 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 monthly. COLUMNS 06 PRESIDENT’S PERSPECTIVE 07 CHAIRMAN’S PERSPECTIVE DEPARTMENTS 30 VAA 2022 PARTNERS 31 CONTRACTOR MEMBER SPOTLIGHT: BIZZACK CONSTRUCTION LLC 31 CONTRACTOR MEMBER SPOTLIGHT: J.C. JOYCE TRUCKING & PAVING CO., INC. ON THE COVER The Chesapeake Bay Bridge's Trestle C Southbound after completion of project. See more details on page 22. Photo courtesy of Mike Dudley. FEATURED GENERATION Z: FUTURE EMPLOYEES AND EMPLOYERS 08 Will Jackson will graduate from RandolphMacon College in December of 2022 with a degree in Business Management. He shares his perspective on what incoming workers are looking for in a job that will become a career. TOWARDS SUSTAINABLE PAVING 10 Like many other state highway agencies, the Virginia Department of Transportation (VDOT) is extensively working to determine how to best incorporate recycled materials such as recycled asphalt pavement (RAP), recycled crumb rubber, and crushed concrete into their roads. WHAT IF BMD IS A FAILURE 16 Researchers and departments of transportation have invested millions of dollars into laboratory asphalt mixture testing in order to improve design and performance. It's been stated that to be successful, a Balanced Mix Design (BMD) process must result in new asphalt mixes that perform better than the “recipe” mixes resulting from conventional Superpave design. But if BMD mixes are no better, will BMD be a failure? A RIBBON OF BLACK: PAVING THE CBBT 22 The Chesapeake Bay Bridge and Tunnel (CBBT) District initiated a multi-year paving project to repave the facility from the south toll plaza to the north toll plaza, both northbound and southbound. The success of the project was recently awarded the Virginia Best Roadway award and the Golden Lute Award, which is the highest honor a project can achieve in Virginia. A SEAMLESS SOLUTION TO DATA COLLECTION 28 The Virginia Asphalt Association, in partnership with HeadLight, is proud to announce HeadLight Smartforms, the digitization of several VDOT forms related to density testing and tack coat application rates. Smartforms not only automates calculations but incorporates pictures for complete project documentation. VIRGINIA ASPHALT A PUBLICATION OF THE VIRGINIA ASPHALT ASSOCIATION 7814 Carousel Lane, Suite 310 Richmond, VA 23294 Phone: (804) 288-3169 Email: cfahed@vaasphalt.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; Kevin Jones; C.R. Langhorne; 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 ronnie@llmpubs.com. ©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 MAY 2022
06 SPRING/SUMMER 2022 Trenton M. Clark, PE, President, Virginia Asphalt Association As I have gotten older, the music I listened to in my teens and twenties is now considered classic rock or classic country. The music wasn’t classic then, but many of those songs have endured the generations. Interestingly, I have found my kids and I listen to some of the same music (notice I used the word “some”). My son Nick actually took me to a Def Leppard and Journey concert as a birthday present a few years back, and I can play “name that song” with my daughter Laura. Why am I reminiscing about music? Music is like many other areas of life—the interests and the concerns span many generations. And while my children and I have a 25- to 30-year age difference, there are topics we can still agree on. In college at Virginia Tech, I thought I wanted to concentrate on an environmental discipline as part of my civil engineering degree. The idea of doing something to protect and improve the environment was starting to gain momentum in the early 1990s. However, it only took one class for me to discover that wasn’t going to be my life’s work. Was the need to protect and improve the environment still important? Yes, but it was not my calling. Thirty years later, the need to protect and improve the environment is front and center for politics, activist groups, and industry. Climate change impacts are part of most news shows and weather reports. Recently, portions of the Infrastructure Investment and Jobs Act (IIJA) federal legislation signed in November 2021 ties environmental stewardship to transportation project funding to slow or reverse climate change. Also in late 2021, the Office of Sustainability was established under the Virginia Secretary of Transportation. Legislation has been introduced at the federal and state levels pushing Buy Clean requirements. And in January 2022, the National Asphalt Pavement Association released their (The) Road Forward plan that sets forth “A Vision for Net Zero Carbon Emissions for the Asphalt Pavement Industry.” Through numerous surveys over the last few years, employees or potential employees look at the environmental stewardship of a company to determine if they will work or continue to work for a company. In fact, a survey by Unily (an intranet company) “revealed that 83% of workers thought their employer was not doing enough to be more sustainable and tackle climate change. What’s more, 65% said they would be more likely to work for a company with robust environmental policies.” (Forbes.com, “Employees Demand that We Become More Sustainable,” October 31, 2021). A quick Google search shows that how a company or industry views environmental stewardship is critical in attracting and retaining employees. With the current stress on the construction industry for needed workforce, an industry cannot ignore the need to employ more sustainable business practices to be viable and profitable. Going back to my music, I always enjoyed the song by Mary Chapin Carpenter called “The Bug” with the lines “Sometimes you’re PRESIDENT’S PERSPECTIVE Be the Windshield the windshield, sometimes you’re the bug.” Carpenter juxtaposes good times and bad throughout her lyrics. Clearly, we want to be the windshield and not the bug. We must lead and not be led. We must be the industry looking through the windshield, leading in sustainability and environmental stewardship. Not only must we continue to embrace ways to reduce our global warming potential for asphalt materials as a goal for our industry, but we must partner with the policymakers, regulators and customers to be able to achieve that goal. As I wrote about in the previous magazine, the asphalt industry must Lead the Change. Lastly, in the summer of 2021 VAA adopted a Vision Statement for the association that was approved by the board. It is clear and straightforward. VAA’s vision is to “be a united voice for the asphalt industry resulting in the betterment of society.” This statement clearly identifies the “why” for VAA—“the betterment of society.” Our industry has been a leader in sustainability for decades—starting with recycling of asphalt materials into new mixes, incorporation of warm mix technologies to lower plant temperatures, and switching to cleaner burning fuels at plants to name just a few. Members of our association are committed to fulfilling our vision through environmental stewardship. We must be the windshield. Being the bug is not an option. To learn more about how asphalt is green, visit the VAA website or contact me. Stay safe! Nick, Trenton, Laura and Nicky at Trenton’s 50th birthday celebration during the VAA 2021 Annual Meeting.
VAASPHALT.ORG 07 I have often said that my father lived to work, because as I grew up, I always saw him working. At the age of 14, my father helped me to get my first job, which was mowing grass at Oak Hill Academy, where he worked. He started work at 7 a.m., while I didn’t start until 8. Work was about 30 minutes from home, but Dad left every morning at 5 a.m. sharp. I had to be in the truck waiting if I wanted to work. I would sleep in the truck until I could clock in. I asked Dad why he left so early every day and he said, “You never know what troubles might happen on the way to work, a flat tire, truck breakdown, etc., and I don’t want to be late.” His reasoning didn’t make sense to me as a teenager. Sleep and time were important! But in his world, work was important. That is how he provided for our family. As I got older, I started to understand his reasoning but also realized we have differences in our rationale. My parents instilled in me the value and importance of doing something right the first time. But for me, work was a way to enhance life. My father lived to work but I work to live. Thinking back on my childhood, I am sure I had it much easier than my parents. As a result of the generation gap, we have differing priorities. Through the generations, priorities are constantly changing. In the workplace, it is easy to see the different generations. The baby-boomers often think the younger generation is lazy because they want to get their work finished and head home. There’s a running joke at our office reserved for someone who is leaving the office at 5 in the evening. Someone will always ask, “Are you just working a half a day today?” While it is all in jest, it does bring to light the difference in work beliefs. Someone working long hours does not necessarily make them a hard worker, just like short hours does not mean someone is lazy. It is all about being effective in the time we work to produce a quality product. We need to understand that all people are different and have different skill sets. A good example of differing skill sets among the generations is that my parents each have tablets that they use for various tasks. Most days, they need technological assistance. In contrast, my 9-year-old grandson walks into their house and his first question is, “What is your wi-fi password?” While my parents are smart, successful people, they did not have the opportunity to grow up with computers, iPads, cell phones, etc. Chris Blevins, PE, Vice President, W-L Construction & Paving, Inc. CHAIRMAN’S PERSPECTIVE It Takes Multiple Generations The same thing goes in our industry as the technology is constantly evolving. We have many new initiatives which help the industry such as Global Positioning System (GPS) equipment, e-ticketing, Paver Mounted Thermal Profiling (PMTP), etc. Often, the most seasoned operators struggle with new technology while it is second nature to the millennials. Our challenge is to have those on our crew collaborate to get the best product. We need the experience of the veteran operator and the proficiency of the millennials to create the very best product. At the end of the day, all generations are proud of a job well done. I will leave you with this quote from Farshad Asl: “True Leadership is having multiple generations working together successfully and passionately to create significance.” Our challenge is to have those on our crew collaborate to get the best product. We need the experience of the veteran operator and the proficiency of the millennials to create the very best product. Chris and Jennifer at Dallas Cowboys home field.
08 SPRING/SUMMER 2022 GENERATION Z: FUTURE EMPLOYEES AND EMPLOYERS Not a Typical Workday My name is Will Jackson. I will graduate from Randolph-Macon College in December of 2022 with a degree in Business Management. After graduation, I will join the workforce as an employee of my family’s business in North Carolina. Ever since I was 10, I have been spending my summers working for my father in the auto body business his grandfather built. Although I have not always had as big a role in the business as I do today, I am very aware of the changes that have happened over time. I remember when my dad bought his first Blackberry smartphone so that he could better manage day-to-day affairs. Change is always happening regardless of the size of a company. I believe that for my generation (Gen Z), working for a company that embraces change is a must. A company that is stuck in the past is less likely to be flexible and attract employees with the ability to change and adapt to everyday situations. When you ask Gen Z what they want in a job, most would say they’re looking for flexibility and not a typical 9-to-5 workday. Now more than ever we want to explore, go new places, and see new things. A job where you have to be there every day and get a week’s vacation once a year doesn’t cut it anymore. The COVID pandemic gave employees and employers the opportunity to see that hybrid jobs work and that it’s not necessary to be in the office all the time. This is something that my generation wants to continue for the rest of their lives. This allows us the work-life balance we feel is so important. When I picture the perfect job, flexibility is a top priority. Looking at my internship with VAA, I see aspects that are very enticing to a Gen Z college student. A flexible workday is something I have never seen before. I’ve always worked from 8 a.m. to 5 p.m. Seeing that the employees at VAA are not always in the office is also refreshing and enticing. Being behind a desk every day can get mundane. Another aspect of a great employer is the people working around you. Happy employees promote a happy workplace and help make any job enjoyable. The perfect job needs employees that work as a team, who are happy to be employed and are friendly. Nobody wants to collaborate with people that are unhappy and hate their job. When I graduate in December, I plan to go back to North Carolina and prepare to run my family business. I want to grow our small local business by adding more locations and making it a great place to work. Not everyone enjoys blue-collar work. To be a competitive employer I will need to implement ideas like the ones I have previously mentioned so that Jackson’s Body Shop can be that “perfect job” for the individuals I need to hire to grow my business and make it a success. Will Jackson, Senior at Randolph-Macon College Barry, Will, Heather, Luke and Jaye (in front). Will Jackson #76 makes a play for the Yellow Jackets.
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VAASPHALT.ORG 11 TOWARDS SUSTAINABLE PAVING Researchers and engineers started looking at asphalt mixtures as a potentially viable “home” to incorporate some of the recycled plastic waste commodity. There is a growing body of literature on the use of recycled plastic waste in asphalt, but much of the documented efforts lack a clear experimental plan and suffer from the use of dated test methods. Moreover, it is still unclear if producing and paving recycled plastic modified (RPM) asphalt mixtures would require any changes to typical paving practices, especially to those in Virginia. Finally, future research was recommended with a particular focus on sourcing and methods of incorporating recycled plastics, material characterization of laboratory and field produced asphalt mixtures modified with recycled plastic waste, plant operations, health and safety, and mainly construction of field demonstration projects and associated short- and long-term performance. What’s in It for Virginia? The initiative of incorporating recycled plastic waste into asphalt mixtures has been on the agency’s radar for years. This initiative promotes defining a sustainable solution for both improving the performance of asphalt pavements in Virginia and diverting waste plastic from being placed in a landfill or incinerated into a secondary use as a commodity replacement for other raw materials. Seven types of plastics are currently identified with various chemical and physical properties (such as melting points and others). With the existence of multiple plastic types and the major uncertainties due to the variabilities in their properties, such an initiative will help the agency gain a gradual knowledge about the types of recycled plastic waste that may be compatible with the paving material typically used in Virginia (e.g., asphalt binders, aggregates and others) and that are expected to result in longer-lasting pavements. As much as we care about diverting plastics and any other material coming from various waste streams (tire rubber, RAP, glass, etc.), we also care about including these materials in a very responsible manner that would guarantee good performance. continues on page 12 △ With the change in recycling streams over the past few years, the interest in diverting plastics from the waste stream for reuse in asphalt has been a growing topic for highway agencies. Like many other state highway agencies, the Virginia Department of Transportation (VDOT) is extensively working to determine how to best incorporate recycled materials such as recycled asphalt pavement (RAP), recycled crumb rubber, and crushed concrete into their roads. With the change in recycling streams over the past few years, the interest in diverting plastics from the waste stream for reuse in asphalt has been a growing topic for highway agencies. In 2017, plastics accounted for 35.4 million tons of waste in the United States with only 3 million tons (8% of the plastic waste) being recycled, 5.6 million tons (16% of the plastic waste) undergoing combustion, and 26.8 million tons (76% of the plastic waste) being stacked and landfilled. Hence, the current plastic waste challenge became a critical concern.
12 SPRING/SUMMER 2022 TOWARDS SUSTAINABLE PAVING Summer 2021 Field Trials One major benchmarking experiment/project was planned and developed for the 2021 paving season. The experiment included two RPM 12.5 mm dense-graded surface mixtures (SM-12.5 P1 and SM-12.5 P2) alongside two typical VDOT control dense-graded mixtures (SM-12.5 D and SM-12.5 E). The first RPMmixture featured the use of a complex arrangement of polyethylene-based polymers designed for the extension and enhancement of asphalt binders used in road surfaces at a rate of 5% by total weight of the employed asphalt binder (herein referred to as “P1”). The second plastic trial featured the use of polyethylene terephthalate-based plastomeric amorphous polymers designed to improve the overall performance at a rate of 3% by total weight of the employed asphalt binder (herein referred to as “P2”). The RPMmixtures were designed to meet the agency’s specifications in terms of gradations and volumetric properties. Both RPMmixtures included 15% RAP and were produced using a PG64S-22 asphalt binder. The mixtures were produced following typical contractor practices. The only difference is that the plastics were added to the mixtures following a “dry process.” The plastics were introduced at the RAP collar behind the flame at the target rates using carefully calibrated fiber feeders to ensure a consistent flow of plastic. They were then mixed with the hot aggregates prior to introducing the asphalt binder as shown in Figure 1. The RPM mixtures were produced at a temperature range of 320 to 330°F. About 700 tons of RPM asphalt mixtures per each recycled plastic product were produced and were placed in the field in a 1.5-inch single lift over the course of 1-mile long adjacent stretches on Old Stage Road in Chester, Richmond, Virginia. The first few tons of RPM mixtures with plastic P1 were produced at a relatively lower temperature (~290 to 300°F) which resulted in the initial roller pattern and control strip not meeting the density specifications. This could be due to the slight increase in stiffness of produced asphalt mixtures when recycled plastic particles were included. To account for that, the production temperature of asphalt mixtures at the plant was increased to 320 to 330°F. As △ continued from page 11 As much as we care about diverting plastics and any other material coming from various waste streams (tire rubber, RAP, glass, etc.), we also care about including these materials in a very responsible manner that would guarantee good performance. Figure 1. (a) feeder machine used for plastic P1, (b) feeder machine used for plastic P2, (c) Polyethylene (PE)-based plastic P1, and (d) Polyethylene Terephthalate (PET)-based plastic P2. (c) (a) (b) (d)
VAASPHALT.ORG 13 TOWARDS SUSTAINABLE PAVING Figure 2. (a) loose RPM asphalt mixtures, (b) RPM pavement being compacted, (c) RPM pavements in-service after 4 months. (a) (b) (c) the night progressed, all core densities passed the requirements. The first night of trials generated several lessons learned. No issues were encountered when producing and paving the second RPM mix (with plastic P2). Figure 2 shows some of the paving operations. No changes from routine established practices in relation to surface preparation or paving operations were reported; standard construction practices and equipment were used. Finally, personnel involved with this effort had not encountered any safety-, health- or environmental-related considerations specific to RPMmixtures that do not apply to standard conventional asphalt mixtures. Do RPM Mixtures Perform Well? An extensive suite of laboratory tests are being performed on asphalt binders and specimens fabricated from the RPM and corresponding control produced mixtures to assess the compatibility of using recycled plastic waste with the raw materials locally available in Virginia. The asphalt specimens include plant mixed plant compacted specimens (no-reheat), plant mixed laboratory compacted specimens (reheat) and plant mixed field compacted specimens (cores) right after paving. The selected tests belong to three levels 10 8 6 4 2 0 Cantabro Mass Loss (%) (a) N/A SM-12.5 D 7.6 8.1 4.4 5.9 3.8 5.4 6.3 8.1 SM-12.5 E SM-12.5 P1 SM-12.5 P2 Design=7.7 Design=6.6 Design=5.0 Non-Reheated Reheated AC = 6.1% FT = 10.1% AC = 6.0% FT = 9.2% AC = 6.8% FT = 11.7% AC = 6.1% FT = 8.8% 350 300 250 200 150 100 50 0 CT Index at 25°C (b) N/A SM-12.5 D 201 182 228 168 257 204 185 118 SM-12.5 E SM-12.5 P1 SM-12.5 P2 Design=68 Design=100 Design=68 Non-Reheated Reheated AC = 6.1% FT = 10.1% AC = 6.0% FT = 9.2% AC = 6.8% FT = 11.7% AC = 6.1% FT = 8.8% Figure 3. Performance test data of RPM and control asphalt mixtures: (a) Cantabro mass loss and (b) IDT-CT. I-bars indicate the parameter variability plus/minus standard deviation. AC = asphalt content and FT = film thickness. of testing complexity: “basic” tests characterized by a short time for specimen preparation and testing without requiring any specific cutting, coring and gluing; “intermediate” tests requiring a longer time for specimen preparation and testing; and “advanced” tests requiring expensive machinery and multiple days to complete and analyze the test results. Figure 3 presents some of the results of the Virginia Balanced Mix Design (BMD) tests when performed on RPM and control specimens fabricated during design and production (i.e., reheats and non-reheats). Overall, the RPMmixture exhibited Cantabro mass loss values relatively greater than the ones observed for SM-12.5 E mix but lower than the ones observed for SM-12.5 D mix; thus, indicating promising durability. As expected, no issues related to rutting were observed when evaluating all mixes using the asphalt pavement analyzer (APA) rut test at 147°F (64°C). The indirect tensile cracking test (IDT-CT) at 77°F (25°C) was performed on all mixtures to evaluate the resistance to cracking. In general, RPMmixes showed cracking tolerance index (CT index) values similar or greater to those of SM-12.5 D and SM-12.5 E mixes. Although, current efforts are comprehensively assessing continues on page 14 △
14 SPRING/SUMMER 2022 TOWARDS SUSTAINABLE PAVING the feasibility of using these tests to evaluate the “true” performance of RPM mixtures, promising preliminary performance of RPM mixtures were observed, making them qualify to act as “D premium mixtures.” Environmental Aspect of the Initiative In addition to evaluating the performance properties of the produced RPM paving materials, there is a major interest in better understanding the potential environmental impacts associated with the use of recycled plastics in asphalt mixtures. For example, per night, this trial helped save the equivalent weight of approximately 635,000 single-use plastic bags going to landfills. This was accompanied by an offset of approximately 10,770 kg of CO2. Although these numbers might seem low because only one trial was done, an increase in using such alternatives can help reduce fossil fuel usage, leading to a reduction in carbon footprint and helping to foster a circular economy. On the other side, along with an increased interest in the reuse of waste plastics, a growing concern has been raised regarding the topic of microplastics in the environment. Lewis N. Lloyd, research scientist at VTRC with expertise in waste management and beneficial reuse of waste material, is handling the environmental aspect of this initiative. His efforts will attempt to detect and quantify the presence of microplastics in material generated from pavement wear that could potentially be introduced into the environment through stormwater runoff. This portion of the research is still in its early stage, and no firm or clear conclusions have been derived yet. Ongoing and Future Work We learned many lessons from this trial about practices covering the mix design and production stages, but there is still more to figure out. Multiple field trials are being planned for the upcoming 2022 paving seasons. These trials are expected to feature similar and new types of plastic waste. Moreover, the research team will continue evaluating the RPM and control mixtures in the laboratory with a major focus on critical long-term aging and in the field through non-destructive testing. One major item on the team’s radar in 2022 is about evaluating the feasibility and the process of recycling asphalt mixtures already containing recycled plastic. This will highlight the impact of such processes on the properties and production of such mixtures, and the potential generation of hazardous emissions on the environment. Acknowledgements This important and extensive effort could not be accomplished without the contribution and hard work of several parties. Appreciation is extended to Thomas Schinkel, the material engineer for VDOT’s Richmond District, for allowing this trial to take place in his district. Support from personnel at VDOT’s Richmond district and VDOT’s Materials Division is greatly appreciated. Sincere appreciation is expressed to Travis Cable, Vice president of quality control, and the team at Colony Construction Inc. In addition, the assistance and support provided by the plastic suppliers MacRebur and Kao Chemicals and the supplier of fiber feeders/machines, Hi-Tech Asphalt Solutions, are greatly appreciated. Finally, appreciation is extended to VTRC leadership and staff for their continuous support of innovative efforts. △ continued from page 13 On the other side, along with an increased interest in the reuse of waste plastics, a growing concern has been raised regarding the topic of microplastics in the environment. This portion of the research is still in its early stage, and no firm or clear conclusions have been derived yet.
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16 SPRING/SUMMER 2022 FAILURE? What if BMD is a Trenton M. Clark, PE, President, Virginia Asphalt Association There Are Many Different Measures of Success For the better part of two decades, researchers and departments of transportation have invested millions of dollars into laboratory asphalt mixture testing in order to improve design and performance. Much effort has been spent on directly measuring the physical engineering properties of asphalt mixtures through devices such as the AMPT (Asphalt Mixture Performance Tester) in an effort to improve the predictive modeling for flexible pavement design. While this approach has benefits, it also has several shortcomings, such as the time required during mix design and usefulness during actual asphalt production. Therefore, researchers and agencies have turned their attention to less complicated testing procedures that can be used during mix design and production. While these procedures do not produce fundamental engineering properties such as modulus and flow number, they do provide a method to assess material performance against a set of minimum or maximum thresholds. Essentially, agencies are hoping to improve cracking resistance while not resulting in rutting/deformation. In other words, balance distress modes to maximize performance. In the end, agencies such as VDOT have stated that to be successful, a Balanced Mix Design (BMD) process must result in new asphalt mixes that perform better than the “recipe” mixes resulting from conventional Superpave design. But if BMDmixes are no better, will BMD be a failure?
VAASPHALT.ORG 17 Background Most design procedures evolve, change and adapt over time. Asphalt mix design is no different. Just look through decades of state highway agency specification books and this will be obvious. What started out as a trial and error approach more than 125 years ago has evolved into a very complicated process. However, the basic ingredients in asphalt mix have not changed—fine aggregates, coarse aggregates and asphalt binder tossed in with some recycled materials and at times polymer modified binder. The evolution over the decades has been the recognition of how these basic ingredients and other additives in various proportions impact performance. During the Marshall Mix Design era (1980s and 1990s), much emphasis was placed on mixture volumetrics—specifically air voids or voids in total mix (VTM), voids filled with asphalt (VFA) and voids in mineral aggregate (VMA). Understanding the role of these mixture properties contributed to significant strides in mixture design. However, it became clear in the late 1970s and early 1980s that properties other than volumetrics must be considered to combat the asphalt rutting and bleeding experienced across the US. These concerns led to the asphalt mix design research efforts under the Strategic Highway Research Program (SHRP) in the mid-1980s. Ultimately, the outcomes from SHRP led to more stringent aggregate properties, a new asphalt binder grading system and design mixture compaction levels as a function of pavement loading. While envisioned as a three-level mixture design process (Level 1 recipe design, Level 2 lab performance design and Level 3 engineering properties design), limitations in lab testing equipment kept state highway agencies at Level 1. However, the lack of robust testing equipment and procedures did not deter researchers and agencies from pursuing Level 2 and Level 3 design processes. The Asphalt Mixture Performance Tester or AMPT device was developed through National Cooperative Highway Research Program (NCHRP) projects 9-19 (Superpave Support and Performance Models Management) and 9-26 (Simple Performance Tester for Superpave Mix Design)1 to achieve Level 3 designs for mixes where the results can be used in mechanistic/mechanistic-empirical flexible pavement design methodologies. While the AMPT has progressed since its continues on page 18 △ Most design procedures evolve, change and adapt over time. Asphalt mix design is no different. What started out as a trial and error approach more than 125 years ago has evolved into a very complicated process. " " Asphalt flushing. WHAT IF BMD IS A FAILURE?
18 SPRING/SUMMER 2022 WHAT IF BMD IS A FAILURE? initial inception in the early 2000s, there has not been widespread adoption by highway agencies or the contracting industry. One drawback to the AMPT is the time required to achieve results. During the mix design process, the turnaround time from specimen preparation to final results is less critical (typically 4 to 5 days). However, if adjustments to the design are needed then the time to final approval can be extensive. Likewise, during the production of asphalt, test results are needed in “real-time” to make adjustments. If the mix design approval is based on fundamental engineering properties and not standard properties such as asphalt content, aggregate gradations and volumetrics, then a contractor will not be able to adjust their mix during production in order to ensure conformance with the mix design. Many days will pass from the time the sample is retrieved to final test results. Recognizing other challenges exist with the production use of AMPT, research moved to focus on Level 2 mix design using lab performance tests, generally referred to as BMD. Many extensive efforts have been underway for the past decade at numerous universities to develop lab performance tests that correlate to in-service performance of asphalt mixes. The most notable early tests developed have been the Illinois I-FIT, the Texas Asphalt Overlay Cracking Test, the Disc Shaped Compact Tension and the Semi-Circular Bend test. Since the development of these procedures and use by state agencies, the Indirect Tensile (IDT) has gained broader acceptance for assessing cracking potential; the Cantabro test for evaluating asphalt mix and durability, and either the Asphalt Pavement Analyzer (APA) or Hamburg wheel tracking device to assess mixture rutting potential. Based on a recent survey of state agencies, 10 states are implementing while others are in the process of either implementing or evaluating BMD tests.2 The Basic Premise As stated earlier, state agencies such as VDOT are investigating or implementing BMD in the hopes that new asphalt mixes perform better than current asphalt mixes. Better performing mixes, while potentially more expensive initially, will have lower life cycle costs due to the better performance and longer service life. Asphalt mix testing. An asphalt sample in IDT test equipment. continues on page 20 △ △ continued from page 17
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20 SPRING/SUMMER 2022 those terms, when compared to the impetus behind BMD implementation, an asphalt mix of equal performance will be deemed a failure. However, is that really the case? BMD can be a success even if the overall performance of asphalt mixes is not improved. There are three main successes agencies can achieve as well as the contracting industry. The first success comes in the area of knowledge. For too long asphalt mixes have been designed to meet a set of metrics—asphalt content, aggregate gradation bands and volumetric properties. In general, this approach has worked. Like any normal distribution of performance, some mixes have performed better than expected, many have performed as expected and Recently, the National Center for Asphalt Technology (NCAT) completed a report for NCHRP (NCHRP Project 20-07 Task 406) outlining a model for BMD implementation. A few important points were made in that report. First, an agency needs to evaluate the numerous lab performance tests available that fit the state. For example, the predominant cracking experienced in Montana will be different than the cracking in Florida. While fatigue cracking may occur in Montana, temperature-induced thermal cracking may be more relevant to the Montana Department of Transportation (MDT) in selecting a cracking test protocol. Florida DOT may be more concerned with fatigue cracking and rutting due to high pavement temperatures. Once a test or set of tests are selected, a second important step is to baseline the current or standard mixes used in the state. As the old adage goes, if you do not know where you are, how can you know where you are going? Through extensive lab testing, contractors and the agency can determine a benchmark or baseline for existing materials by nominal maximum aggregate size and binder type. By cross-referencing the standard mixes with performance data from a pavement management system, an agency can begin to determine what “better” means by using BMD. But What if Better Isn’t Achieved? While so much time, effort and funding has been invested in BMD, what if BMD does not produce better mixes? What if the only outcome is a different mix design process? Would that make BMD is a failure? According to Merriam-Webster’s Dictionary, failure is defined as “omission of occurrence or performance, state of inability to perform a normal function…a lack of success.” In △ continued from page 18 Agencies should not miss the forest for the trees. Proper implementation of a performance-based BMD approach will have long term benefits through knowledge gained, reduced costs, and improved sustainability. " " WHAT IF BMD IS A FAILURE? BMD experimental mix being laid at VTTI.
VAASPHALT.ORG 21 WHAT IF BMD IS A FAILURE? others have not performed well at all. Without immediate failures, the bad performers are not identified without tying the job mix formula to measured field data many years after the mix was produced. By understanding the overall lab performance of mixes and establishing actual baselines, each existing or new mix design can be assessed. The contractor and the agency can evaluate ways to improve lab performance outcomes that may improve performance in the field that would benefit the agency. The second success can be seen in reduced costs to the taxpayer. These reductions may be in terms of initial cost, i.e., producing the asphalt, or long-term in lower life cycle cost. In a performance-based BMD approach, the actual performance of the mixture is paramount. Except for certain criteria such as design and production VTM as well as top-sized aggregate (function of lift thickness and pavement design), contractors are free to design mixes that meet or exceed the performance criteria. For some contractors, that may change the amount of recycled asphalt pavement (RAP) or asphalt shingles (RAS) used in a mix. This could lead to cost savings for the contractor and agency. The contractor may be able to use more local aggregates and not have to truck in special materials to meet gradation bands and volumetric properties. Again, this will be a cost savings. A combination of recycled materials, specialty binders and mix additives could result in lower costing or better performing materials. Whether it is lower costs or longer performance by eliminating poorer performing mixes, the cost to the taxpayer should be reduced. Finally, success can be seen in terms of sustainability. Performance-based BMD mixes will be more sustainable, especially in urban areas where RAP and RAS are abundant. Incorporation of RAP and RAS beyond the current limits in most state agency specifications will reduce the demands for virgin aggregates and virgin asphalt binders. In terms of aggregates alone, this will extend the life of quarries and reduce the amount of energy needed to blast, haul, crush and truck materials to asphalt plants. Binder additives such as softeners and rejuvenators will allow aged asphalt binder in RAP and RAS to be better utilized in new mixes. Mix additives such as ground tire rubber, crumb rubber and various fibers can be part of performance designed mixes. Many of the additives are products of other waste streams or by-products. And while the research is still being conducted and consensus conclusions still not obtained, plastics may be in future asphalt mixes. To understand the impacts on performance, BMD will be an assessment tool. Don’t Miss the Forest for the Trees Will BMD result in better mixes? The hopeful answer to that question is “yes.” However, it will be many years before an agency will be able to definitively answer that. Even if the newmixes meet certain criteria during design and production, will the change in actual performance be measurable? Given the number of factors that contribute to the actual performance of a mix, improvement may be a nebulous term. In the meantime, agencies should not miss the forest for the trees. Proper implementation of a performance-based BMD approach will have long term benefits through knowledge gained, reduced costs, and improved sustainability. References 1. “TechBrief: Asphalt Mixture Performance Tester,” FHWA 2013, https://www.fhwa.dot.gov/pavement/asphalt/pubs/ hif13005.pdf 2. “Facilitating Balanced Mix Design Implementation,” NCHRP 20-44(27) Project Description, https://apps.trb.org/ cmsfeed/TRBNetProjectDisplay.asp?ProjectID=4920
Craig Rayfield, Quality Control Manager, Allan Myers Trestle C northbound paving operations—traffic was put back into the original configuration with 2-way traffic on the southbound C trestle. This allowed for a safe work zone due to the northbound trestle having no shoulder. A RIBBON OFBLACK PavingtheCBI3–i SPRING/SUMMER 2022 22
VAASPHALT.ORG 23 The Chesapeake Bay Bridge and Tunnel (CBBT) District initiated a multi-year paving project to repave the facility from the south toll plaza to the north toll plaza, both northbound and southbound. Allan Myers secured the winning bid for the project. The goal: an asphalt surface with a 20-year lifespan placed on this unique bridge-tunnel system. The success of the project was recently highlighted by the Virginia Asphalt Association awarding it the Virginia Best Roadway award and the Golden Lute award, which is the highest honor a project can achieve in Virginia. What makes this project unique is that all milling and paving operations occurred roughly 35 feet above the Chesapeake Bay. Work was done in single lane closure configurations over the original 75-foot concrete trestle built in the 1960s and the new 300-foot trestles were completed and opened to traffic in April 1999. Once Allan Myers was awarded the contract, the team immediately developed detailed safety plans for approval by the CBBT District. Highway work is always dangerous, but working on a bridge deck with no place for traffic or crews to escape in the event of an incident brought a new focus to safety. When the time came for Maintenance of Traffic (MOT) setups and protection, nothing was left to chance. Additional signage was posted along with new barrels and cones for added visibility. A fleet of attenuator trucks was used to protect every operation in the work zones, and the CBBT police increased patrols as well. Myers developed specific routes for crews to access and egress the work zones and created staging areas for personal vehicles and equipment. The team used 24-hour MOT patrols when multiple closures on multiple trestles were required to allow for milling and paving operations along with cleanup operations, concrete deck repairs and joint repairs and installs. Allan Myers’s safety motto “Home Safe Tonight” was taken to new levels to ensure all workers went home safe each night. Trestle C southbound after milling and cleanup, ready to be tacked and edges sealed. You can see the drain outlets that had to be sealed with foam backing to prevent material from leaving the deck. A RIBBON OF BLACK: PAVING THE CBBT continues on page 24 △ Chesapeake Bay Bridge and Tunnel District.
24 SPRING/SUMMER 2022 The smoothness of the ride felt by the traveling public, called the camber, is an important consideration when paving a roadway. The original contract did not have a camber specification, but Allan Myers added a requirement to the contract to improve the camber by a minimum of 20%. All the trestles were tested, pre-mill ride data was evaluated, and targets and goals were established for the paving crews. Kicking Off With Milling Once all crew members received safety training, the milling operation started on the C trestle southbound outside travel lane with multiple milling crews to remove all the asphalt material down to the concrete deck. This process was started by a support crew installing drain protection in each drain slot to prevent millings from falling into the cable trays and then into the Chesapeake Bay. Once the material was removed and decks were cleaned, any needed concrete repairs were made. Once both layers were completed, the bridge support crew cut out the asphalt and prepped each joint for the installation of elastomeric joint material every 300 feet fullwidth across the deck. Trestle C southbound after milling and cleanup, ready to be tacked and edges sealed. You can see the drain outlets that had to be sealed with foam backing to prevent material from leaving the deck. Myers then kicked off the 2020 paving season by starting the C and D trestles northbound. The CBBT District permitted Myers to close the full span from Island 4 to just before the northside toll plaza, which entailed moving traffic to a two-way configuration on the southbound lanes for more than seven miles. Three MOT setup trucks were used the night of the traffic switch to quickly remove the seven-plus miles of lane closure. With every barrel and cone being triple weighted, it was quite an undertaking. Trestle C northbound paving operations— traffic was put back into the original configuration with 2-way traffic on the southbound C trestle. This allowed for a safe work zone due to the northbound trestle having no shoulder. C and D trestles northbound were the first sections where the team encountered the angle iron end dams on each of the 75-foot A RIBBON OF BLACK: PAVING THE CBBT Trestle C northbound being paved. bridge decks. The milling on this section compared to the southbound section was slow and methodical. The mill had to pick up every 75 feet to prevent any damage to the metal dams. Each of the joints then had to be milled using skid steer milling attachments and any remaining material chipped out. Once the joints and deck were milled and cleaned, everything was inspected. Any needed repairs were made to concrete decks and joints were cut and new sections welded into place as needed. Once the section was approved for paving, the leveling course was installed. The method to install this course was planned out and carefully executed by the crew to reduce the camber feel and to level out the spans so the final course could be installed in a consistent and level 1 1/2-inch lift. Myers also wanted to be able to pave over all the joints in the section to ensure a smooth and consistent final layer. To ensure the CBBT District was completely satisfied with the results, a section was milled out and repaved to confirm the ride they were looking for on the final layer. Allan Myers repeated the process that was learned on northbound trestle C to ensure that trestle B and trestle A northbound exceeded the requirements and high standards that were set upon the completion of trestle C. Roughly 668 joints on the northbound trestle were milled, cleaned and paved over. Strict Moisture Control The southbound trestle offered a simpler approach for the milling and paving crews due to the method of construction of the new sections. Each southbound span was 300 feet in length and did not have metal angle joints. The method used for the separation between spans was an elastomeric joint compound. These joints allowed the milling crew to mill through them so once the deck was cleaned, the joint areas were covered with strips of plywood to prevent any asphalt material from dropping through during the installation of the leveling course and the final layer. When the paving operation was complete, the bridge support crew would lay out the area and saw-cut the material to be removed. Forms were then installed to allow the elastomeric compound to be placed to form the end joints. Each southbound joint required mixing and installation of roughly 300 gallons of material. The area had to be completely voided of moisture. Once the mixing △ continued from page 23 continues on page 27 △ Highway work is always dangerous, but working on a bridge deck with no place for traffic or crews to escape in the event of an incident brought a new focus to safety. When the time came for Maintenance of Traffic (MOT) setups and protection, nothing was left to chance.
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A RIBBON OF BLACK: PAVING THE CBBT Milling southbound trestle E. Trestle F southbound milling operation. SPRING/SUMMER 2022 26
VAASPHALT.ORG 27 started, the material had about 30 minutes of workability before starting to set up. It was a significant operation with more than 180 of these joints to prep and install. This project offered many unique challenges, from safety to scheduling the majority of the work during the COVID-19 pandemic of 2020. The Allan Myers team held numerous planning sessions prior to the first shift with the field managers, superintendents, safety managers and quality control personnel to ensure that the aggressive schedule could be met. All plans and procedures were approved by the CBBT District and the CBBT Police to ensure the team provided world-class performance on the project. The Myers team managed the factors within their control, but the weather was often unpredictable. Storms seemingly appeared from nowhere and the CBBT District had very strict wind restrictions. Even on sunny, clear days, wind conditions could prevent trucks from being on the bridge. A passing shower at night could prevent a paving shift due to the extreme requirement with moisture or even an elastomeric shift for the joints. With thorough planning and proper mitigation of the challenges outlined, the project resulted in an average IRI value of 59.69 for smoothness. Allan Myers provided worldclass results to the CBBT District for this most unique project, ensuring that one of the Engineering Wonders of the World will be protected from the elements for many years moving forward. Allan Myers would like to thank the following crews for their participation in the project that helped to make it an overwhelming success: Nick Giorgio: Project Superintendent Craig Rayfield: Paving Quality Control Manager Mike Anderson: Paving Superintendent Scott Durgin: Paving Field Manager James Markham: Paving Field Manager Junior Guilliams: Milling Field Manager Robert Heater: Milling Field Manager Robert Mack: Bridge Field Manager Chesapeake Asphalt Plant & Lab Allan Myers Trucking Division Allan Myers Safety Division Allan Myers Administrative staff (Glen Allen and Chesapeake offices) Allan Myers Maintenance Toano Shop and Field Mechanics A RIBBON OF BLACK: PAVING THE CBBT △ continued from page 24 Allan Myers provided world-class results to the CBBT District for this most unique project, ensuring that one of the Engineering Wonders of the World will be protected from the elements for many years moving forward.
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