PLUS VTRC Update How Production and Variability Impact Balanced Mix Design Perpetual Pavements Shine in Virginia Rethinking Reality The Evolution of Acceptance Testing A PUBLICATION OF THE VIRGINIA ASPHALT ASSOCIATION // FALL & WINTER ISSUE 2023
Fall/Winter 2023 INSIDE THIS ISSUE Visit vaasphalt.org and follow us on Facebook and LinkedIn for up to date industry and association news. COLUMNS 06 CHAIRMAN’S PERSPECTIVE 08 PRESIDENT’S PERSPECTIVE DEPARTMENTS 30 VAA 2023 PARTNERS 31 ASSOCIATE MEMBER SPOTLIGHT: R&B CRUSHING VTRC UPDATE 10 How production and variability impact balanced mix design. RETHINKING REALITY 13 The evolution of acceptance testing. PERPETUAL PAVEMENTS SHINE IN VIRGINIA 17 Two 2022 projects win Virginia accolades for being built-to-last. WOMEN OF ASPHALT’S 23 IN 2023 20 A spotlight on a mentor and leader among women in the industry. BACK TO BASICS: ASPHALT MIX SEGREGATION 22 Taking preventative measures against segregation at the plant level. BACK TO BASICS: SEGREGATION IN THE FIELD 24 A closer look at five main areas in the field where segregation occurs. GETTING TO KNOW RESEARCH DIRECTOR G. MICHAEL FITCH 26 A brief Q&A with the Virginia Transportation Research Council’s (VTRC) Director of Research, Michael Fitch, Ph.D. OCTOBERFEST 28 VAA’s three-day fall event. POWER VERSUS SUSTAINABILITY 31 What are our equipment members doing to lower the energy spent on paving projects? 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 David White Vice Chairman Bobby Hedrick Secretary Tim Boone Treasurer David Branscome, Jr. 1st Ex-Officio Chris Blevins 2nd Ex-Officio David Horton Directors Ken Arthur; Scott Claud; Sheila Cramer; Ed Dalrymple, Jr.; David Helmick; C.R. Langhorne; Buddy League; Ben Miller; Lonnie Minson; Rob Schwear; 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. Fortune 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. ©2023 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 2023 VAASPHALT.ORG 05
The Virginia Asphalt Association (VAA) Board of Directors and Vision 2030 Implementation Team members recently returned from our Strategic Retreat, during which our mission was to predict the unpredictable. Yes, you heard that right! What is the industry’s future, and are we positioned to make a positive impact? I would love to tell you we figured it all out, but we did engage in thoughtful discussion as we strategized and planned for the road ahead. We explored numerous topics, some of which are in their infancy today and will only amplify in the future. Topics like innovation, sustainability, and workforce were all wrestled with as we tried to decipher what lies ahead for the asphalt industry. The asphalt industry is often overlooked in the grand scheme of technological advancements, and yet it is amazing to realize where we are and wonder where we might be in the next five to ten years. Already, we’ve harnessed the power of data analytics, revolutionizing how we make decisions. We’re using sensors and monitoring systems to collect real-time data on factors such as temperature, compaction, and density during construction to ensure quality and reduce costly repairs. Fleet management systems and intelligent construction technologies improve efficiency and quality of products and operations. Artificial intelligence and robotics are already operational at asphalt plants, updating predictive maintenance measures by safely gathering infrared and vibration analysis, and resulting in more uptime and higher quality performance. If autonomous construction vehicles are gradually making their way into the industry, what else is on the horizon? A completely autonomous paving train? Ten years ago, I would have said, “not in my lifetime,” to what is already happening today! So, the question remains: how do we position ourselves to lead in this ever-evolving landscape? “Environment” and “climate” are words we hear and read about every day. The next generation of people we work with and for will require a certain level of environmental stewardship from all products and services, regardless of their affiliated political party. This will be a continuous journey of improvement for all industries, and the asphalt industry will be no different. The encouraging news is that we already have a great start. Our industry has demonstrated exceptional commitment to environmental stewardship through innovative practices such as warm-mix asphalt and recycling technologies, significantly reducing our carbon footprint. We will keep chasing excellence by using environmental production declarations and lowering CHAIRMAN’S PERSPECTIVE Leading Into the Unknown David A. White, President, Superior Paving Corp. greenhouse gases within our operations. These efforts pave the way for more sustainable roads and exemplify the industry’s dedication to a greener future. Another consistent challenge heard through industries like ours is securing a skilled and sustainable workforce. As many in our industry approach retirement, there is a growing need to attract and retain a new generation of workers who are knowledgeable in modern asphalt technologies and processes. We believe the VAA is uniquely positioned to help members successfully attract a talented workforce by investing in training and education programs like the Virginia Education Center for Asphalt Technology and the Virginia Infrastructure Academy in partnership with local community colleges. These are all critical strategies to help address the workforce challenge and ensure the asphalt industry’s continued growth. As the recent retreat for the Vision 2030 team and VAA Board highlighted, we are embracing innovation, sustainability, and workforce as key pillars of opportunity. We’re making asphalt construction smarter, more efficient, and more sustainable through environmental stewardship and building a skilled workforce. While the future may be uncertain, our industry is poised for continued progress and resilience. We are embracing innovation, sustainability, and workforce as key pillars of opportunity. We’re making asphalt construction smarter, more efficient, and more sustainable through environmental stewardship and building a skilled workforce. 06 FALL/WINTER 2023
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When I first started working for the Virginia Department of Transportation (VDOT) in 1998, the agency’s slogan was “We Keep Virginia Moving.” That slogan did not explain how VDOT was going to keep Virginia moving, but it did make it clear that the focus was on the transportation of people and goods across the Commonwealth. In the 25 years since my first day at VDOT, a lot has changed, and a lot has stayed the same. VDOT still builds most pavements out of asphalt; VDOT still constructs bridges and the occasional tunnel; and VDOT is still moving. But it is easy to point out how many of the materials and approaches used to construct and maintain the highway network have changed and advanced. I have two favorite sayings. One from Thomas Edison: “Results! Why, man, I have gotten a lot of results. I know several thousand things that won’t work.” The other, while attributed to Albert Einstein but with no proof, is the quote, “The definition of insanity is doing the same thing over and over again and expecting a different result.” Both quotes tie together hard work, but Edison was looking to learn, and the unknown author pointed out the foolishness of expecting change when nothing changes. As the transportation industry continues to press forward in delivering a safe, economical, long-lasting system, we must remember the lesson in these two quotes. Forces that will impact the asphalt industry will come from all directions. In the last 36 months, we have seen the impacts of COVID-19, inflation, supply chain disruptions, workforce scarcity, knowledge depletion, funding, regulations, special interest groups; and the list goes on and on. As an industry, we should ask ourselves— what must change to control the fate of the industry; and are we willing to make those changes? This was the focal question posed to the Virginia Asphalt Association PRESIDENT’S PERSPECTIVE Keep Moving Trenton M. Clark, PE, President, Virginia Asphalt Association Board of Directors and invited members at the September 2023 Strategic Retreat. The attendees agreed that the asphalt industry must be proactive, but it would not be easy. Many of the forces are out of our direct control. However, we may be able to educate, influence, and position asphalt as the material of choice for pavement owners. As the association winds down 2023 and begins plans for the coming years, we are asking those tough questions. Why are we doing this, and does it really make a difference? Are we following the path of insanity, or are we learning thousands of ways not to do something? We can press the easy button and choose not to make any changes out of complacency or fear, but we cannot repeat the same activities and expect a change. Just as the VDOT slogan “We Keep Virginia Moving” implies, VAA will be focused on providing those services necessary to promote the asphalt industry. Some may be subtle, and others may appear drastic, but nothing will be done without forethought. As you enter 2024, what are you doing to Keep Moving? Stay safe! Just as the VDOT slogan “We Keep Virginia Moving” implies, VAA will be focused on providing those services necessary to promote the asphalt industry. Some may be subtle, and others may appear drastic, but nothing will be done without forethought. 08 FALL/WINTER 2023
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VTRC UPDATE HOW PRODUCTION AND VARIABILITY IMPACT BALANCED MIX DESIGN Stacey Diefenderfer, Ph.D., PE, Associate Principal Research Scientist, Virginia Transportation Research Council Ilker Boz, Ph.D., Research Scientist, Virginia Transportation Research Council The Virginia Transportation Research Council (VTRC) recently completed the second phase of a project investigating how materials variability impacts balanced mix design (BMD) test results during production. While the first phase of the work was performed at the National Center for Asphalt Technology (NCAT) and used lab-produced mixes to evaluate the impact of acceptable volumetric variations on BMD test results, this second phase overlaid the information with actual production data. The results of this effort demonstrate how variability in mix properties during production can impact BMD test results. Only Cantabro mass loss and Indirect Tensile Cracking Tolerance (IDT-CT) test results are addressed; and only one sample in the study failed the asphalt pavement analyzer (APA) rut depth requirement, which supports the anecdotal concerns that mixes are being under-asphalted. Thirteen production mixes, of which ten were BMD mixes and three were non-BMD mixes, are discussed herein. Naming conventions were used for the mixes that consist of a letter indicating a single plant (A-F), reclaimed asphalt pavement or RAP content xR (where x indicates RAP content by weight), asphalt binder type PG yy-yy (where yy-yy indicates performance grade), and, if present, an additive (recycling agent, RA, or For charts, black stars indicate the design JMF values and black plus signs indicate the O-J lab-produced values. Solid circles and squares indicate individual sample results, while hollow blue circles and red squares show the mix average. Green and orange symbols indicate the lab-produced mix variations. Mass Loss Figure 1 shows the lab-produced mix test results for mass loss overlaid with the production and reheat sample values. From design and production, one JMF and seven reheat samples failed the mass loss requirement of 7.5%. The failing JMF (B 30R PG 64S-22) was a non-BMD mix. No production samples failed the mass loss requirement. The average production mass loss values were always less than average reheat mass loss values, likely due to the additional aging introduced during the reheating process. Average production values were also less than JMF mass loss values, except for three mixes: C 35R PG 58-28, E 35R PG 58-28 RA, and E 35R PG 58-28 Softening Oil + Fiber. In seven of the thirteen cases, the reheat sample mass loss values bracket the JMF values. Only two mixes (E 35R PG 58-28 Softening Oil + Fiber and F 40R PG 58-28) are shown to have all production samples, reheat samples, and lab-produced variations pass the mass loss requirement. The lab-produced mixes show the influence of materials variability on the mass loss results. Only seven of the thirteen O-J mixes passed the mass loss criterion. All lab- produced mixes were made from aggregate and RAP sampled at production, except for a few instances when resampling was required. The variations in stockpile gradation and RAP likely resulted in the O-J mass losses being different from those submitted with the JMF. Considering the controlled variations of the lab-produced mixes, the L-J and O-C variations were most likely to fail mass loss, together comprising 53% of the failures and followed by the O-J and O-F variations at 19% other additive). Production samples were not reheated before specimen fabrication; reheat samples cooled after sampling and were reheated for specimen fabrication. For the lab-produced mixes, O indicates optimum asphalt content; L and H signify higher and lower asphalt content, respectively; C and F designate coarser and finer gradation, respectively; and J denotes the job-mix formula (JMF) gradation. Figure 1. Mass Loss. Dashed line indicates a maximum acceptable mass loss. R = RAP content; PG = performance grade; RA = recycling agent; JMF = job mix formula; O = optimum asphalt content; L = low asphalt content; H = high asphalt content; C = coarse gradation; F = fine gradation J = JMF gradation. 10 FALL/WINTER 2023
VTRC UPDATE continues on page 12 △ and 13% of failures, respectively. The failure of these variations indicates that the mixes were designed close enough to the mass loss criterion that aggregate gradation variability or lower asphalt content could cause the initial passing JMF to fail during production. The H-J variation provided the lowest values of mass loss 77% of the time. In addition, the H-J, H-C, and H-F variations improved the mass loss over the O-J mix in every case. This indicates that increased asphalt content is likely the most effective means of lowering mass loss. The impact of the gradation variations are less clear cut as their effects depend on the initial aggregate structure. CT Index Figure 2 shows the lab-produced Cracking Tolerance (CT) Index values overlaid with the production and reheat sample values. From design and production, one JMF and six reheat samples failed the CT index requirement of 70. The failing JMF (B 30R PG 64S-22) was a non-BMD mix. Note that these mixes predate the current production requirement of CT index greater than or equal to 95; however, if the production requirement of 95 were applied to these mixes, six production samples would fail the requirement, along with one production mix (A 40R PG 58-28). Except for one mix (E 35R PG 58-28 RA), average production CT index values were always greater than the average reheat CT index, likely due to the additional aging introduced during the reheating process. Average production values were also greater than JMF CT index values except for B 40R PG 64S-22 RA and C 35R PG 58-28. In seven of the thirteen cases, the reheat sample CT index values bracket the JMF value. For the remaining six cases, half had JMF CT index values lower than both production and reheat values, while for the remaining three, the production samples bracketed the JMF CT index value. Only three mixes (C 35R PG 58-28, E 35R PG 58-28 RA, and E 35R PG 58-28 Softening Oil + Fiber) had all lab-produced variations, production samples, and reheat samples pass the CT index criterion of 70. As with the mass loss, the lab-produced mixes show the influence of materials variability on the CT index results. Only 8 of the 13 O-J mixes passed the CT criterion of 70. Of those eight, four had CT index values less than the JMF while four had values greater than the JMF value. The L-J variation was most likely to fail the CT index criterion, with a 70% failure rate, while the O-C and O-F variations were the next most likely condition to fail, with each having a 46% failure rate. These results indicate that the optimum asphalt content is being selected too close to the CT index minimum value of 70 during design to provide assurance that a mix will not fail during production due to gradation or asphalt content varying within the acceptable tolerance limits. This is further indicated as the H-J variation improved the CT index values over that of the O-J variation for every mix. Additional analysis was performed to compare the average test result of each individual lab-produced mix variation (e.g., O-F) to the average O-J test result using the CT index difference two-sigma limit (d2s) precision estimates for single-operator and multi-laboratory conditions. This analysis was performed to investigate if the production tolerance limits for gradation and asphalt content produce test results that are wider or tighter than the variability of the CT index test method. Table 1 shows the results of this analysis. For most of the mixes, the test results between the O-J and variations in coarse and fine aggregates did not statistically differ, as seen in Table 1. Only 2 and 3 out of 14 observations were statistically significant for O-C and O-F variations, respectively. These results generally indicate that the test variability is similar or wider than the variation induced from the production tolerance limits on coarse and fine aggregates. This further indicates that the current gradation tolerance limits are appropriate to apply in the context of the IDT-CT test. Figure 2. CT Index. Dashed line indicates the minimum acceptable CT index. CT = cracking tolerance; R = RAP content; N/A = data not available; PG = performance grade; RA = recycling agent; JMF = job mix formula; O = optimum asphalt content; L = low asphalt content; H = high asphalt content; C = coarse gradation; F = fine gradation J = JMF gradation. Mix Variation Number (Percent) of Mixes Exceeding the d2s Boundaries Single Operator Multi-laboratory O-C 2 (14.3%) 0 (0.0%) O-F 3 (21.4%) 0 (0.0%) L-J 11 (78.6%) 1 (7.1%) L-C 1 (50.0%) 1 (50.0%) L-F 2 (100.0%) 1 (50.0%) H-J 9 (64.3%) 1 (7.1%) H-C 2 (100.0%) 0 (0.0%) H-F 0 (0.0%) 0 (0.0%) Table 1. Analysis Results Summary for Pairwise Comparison between O-J Mix and Its Variations. O = optimum asphalt content; L = low asphalt content; H = high asphalt content; C = coarse gradation; F = fine gradation; J = JMF gradation. VAASPHALT.ORG 11
VTRC UPDATE On the other hand, the O-J mix test results statistically differed from most of the variation mixes, primarily due to variations in asphalt content. In some combinations, the differences even exceeded the d2s limits of the multi-laboratory precision estimate, a considerably wider boundary than the d2s single operator boundary. The decrease and increase in asphalt content with no change in gradation resulted in statistically different outcomes for 78.6% and 64.3% of the L-J and H-J variation mixes, respectively. Although the interaction mixes had statistically different results, this was also mainly driven by the asphalt content changes. Generally speaking, the results indicate that the variations in CT index values caused by asphalt content variation within the production tolerance limits are significantly wider than the test variability, increasing the risk of failing the IDT-CT test during production, even when asphalt content varies within acceptable tolerances. Industry Implications What does this mean for the industry? Overall, the variability for each material being used in a mix needs to be understood, monitored, and accounted for during design and production to minimize the risk of a BMD failure. While the study recommendations address the IDT-CT test, they demonstrate the importance of good design practices and quality control to ensure passing results for all BMD tests. Designing to account for material and test variations, along with improved aggregate stockpile management, RAP management, and use of consistent asphalt sources will be keys for success in producing consistent, acceptable BMD mixes. Study Conclusions: • From the perspective of the IDT-CT test, current material tolerance limits on aggregates are also appropriate for the BMD concept. The risk of IDT-CT failure is minimal when mix gradations remain within the tolerances for acceptance. However, sudden deviations or continuing drift from target values may result in test failure. • From the perspective of the IDT-CT test, asphalt content during production is the single most influential factor influencing potential failures. Designing a mix with both suitable asphalt content for performance and consistent control of the asphalt content during production is extremely important to meet IDT-CT requirements. Also, a consistent asphalt source will minimize the likelihood of changes in the asphalt binder performance that may adversely impact test results. • Asphalt mixes designed with an average performance result within the single-operator precision estimates of performance thresholds may risk failures during production due to inherent material and test variability. This means that, especially for mixes with CT index values within a single operator tolerance of the CT index limit, additional quality control efforts may be necessary to ensure the mixes remain balanced during production. The single operator variability limits for the design CT index is 70 to 88 CT units. If mixes are designed within this range, the risk for failures due to material and test variability increases significantly. These risks can be mitigated by designing for a CT index value of at least one d2s above the minimum criteria (a value of 88) or by improving quality control of materials and production. △ continued from page 11 12 FALL/WINTER 2023
Have you ever wondered why things are the way they are? Why is a baseball game nine innings? Why is a basketball goal ten feet from the ground? Or why does the Virginia Department of Transportation (VDOT) use asphalt content and gradation for asphalt mixture acceptance? All of these are great questions, and the reasons are based on sound logic, but are they non-negotiable or open to improvement? Modern baseball traces its roots back to 1845, when the first rules of the game were established, but no one can claim today’s game follows the same rules as nearly 180 years ago. Recent changes to the game include the pitch clock and the use of replay. Major League Baseball had to make changes to keep up with innovations and the interest of fans. The same can be said of basketball. The National Basketball Association has continued to make changes to the rules and the court. Think, for example, about the rule against flopping and the movement of the three-point line as players become better shooters. As times have changed, so have the games. Is it time to change the way asphalt materials and pavements are accepted? Over the last five years, Virginia has been at the forefront of researching and implementing carried out by state employees were transferred to contractors. Before the shift, VDOT staff controlled the asphalt plants, directed the mix designs, and adjusted at the plant and in the field. In other words, VDOT was responsible for all testing and acceptance processes. Like many changes in industry or life, a disrupter came along, resulting in a new way of doing business. A quality assurance process utilizing contractor test results caused a paradigm shift. Contractors had to learn how to design asphalt mixes, how to test asphalt mixes, and how to ensure quality. The Virginia Asphalt Association (VAA) and VDOT had to hold training classes to teach the workforce how to perform the tasks once performed by VDOT alone. Outside experts were hired, and VAA staff had to know as much or more than the members to serve as a technical resource. By 1995, states like Virginia were relying on contractor test results in the project acceptance process. Each state had their own approach to performing this process, so there was a lack of uniformity as well as no federal requirements. Recognizing the large federal investment in state DOT programs, a new federal regulation was established: 23 CFR 637. This regulation established RETHINKING REALITY Trenton M. Clark, PE, President, Virginia Asphalt Association continues on page 14 △ THE EVOLUTION OF ACCEPTANCE TESTING balanced mix design (BMD). Starting in the late 1990s, VDOT began using inertial road profilers to measure and pay for smoothness instead of a California-type profilograph. With the implementation of the “Blueprint” in 2009, VDOT had to adjust the plant and field quality assurance programs due to a reduction in staff. These are some of the changes made over 25 years to the asphalt acceptance program. However, are the specifications and approaches developed and implemented over the last 30 or 40 years appropriate for tomorrow’s challenges? Maybe. Maybe not. CURRENT PROCESS Much of the processes used to accept asphalt mixes at the plant and placement in the field date back to the 1980s. During that time, VDOT had a reduction in staffing, and many of the roles and responsibilities VAASPHALT.ORG 13
the minimum criteria required for Quality Assurance (subpart B) on all federal-aid projects on the National Highway System. It is important to note this new regulation was restricted to a subset of projects on the NHS, but many states chose to apply this approach to most or all projects. The purpose for this regulation was to ensure that the materials and workmanship performed on a project met the minimum criteria set forth in a contract or specifications where Federal Highway Administration (FHWA) funded via reimbursement to the DOT. Today, VDOT follows a robust program to verify and validate contractor test results in the lab and in the field. Statistical comparisons are made on individual test results as well as lots of material. For compaction/density in the field, a combination of processes is followed to verify results. Like anything, the approach used by VDOT has evolved—but can it improve? FUTURE APPROACH So, what must change—or stay firm—when implementing a new approach? With the development of technology and changes in the workforce, we should debate new approaches to acceptance; but we must first agree what non-negotiables qualities should be monitored and measured, and if those qualities apply to every project or only the applicable metrics. Meanwhile, quality materials and workmanship in the final product must not be jeopardized. While there may be debate on the metrics, five non-negotiables rise to the top: mix quality, mat compaction, surface uniformity, layer bonding, and pavement smoothness. Other than a non-subjective approach to determine surface uniformity, the other four qualities are part of VDOTs acceptance and payment process. So, what is the difference? Simple. How the process is administered, and the technology utilized. START RIGHT, STAY RIGHT Before the first ton of mix is shipped to the project, it must be produced. Prior to production, the mix must be designed, validated, and confirmed. This is nothing new. The tests used to approve mixes, however, have changed from the Marshall Era to SUPERPAVE to BMD. During production, the amount of testing by the contractor and the independent validation/verification testing by VDOT should follow a risk-based approach. All mixes in all situations should not have the same level of sampling and testing. Subdivision streets and high-volume interstates do not carry the same level of risk, so the sampling frequency and testing regimen should be different. This will allow VDOT and the contractor to focus on those mixes being supplied to high-priority routes (i.e., interstates, high-volume primary routes, and high-volume secondary routes) and adjust the limited resources accordingly. (Note: in 2024, VDOT’s specifications on testing asphalt surface mixes will vary during production. An important first step in a future approach.) TAKING IT TO THE STREET Arguably, the biggest adjustment to a future acceptance approach will be in the field. What will be the role of the inspector, and what technology(s) will be employed to ensure quality installation and workmanship? In nearly every instance, the compaction or in-place density of the asphalt material is deemed the most important quality metric. At this point, destructive and non- destructive testing protocols are followed to determine the acceptance of a lot and sublot of material. While a stratified random approach is used to select the testing locations, the amount of area tested is very small. Further evaluation and piloting of equipment to cover a larger area of the mat is the next step. Instead of a straight average for density, other statistical measures such as cumulative distribution or percentage of the mat meeting or exceeding a minimum density may be more appropriate. However, it is important to note with density and other field quality metrics, this will not be a one-size-fits-all-projects approach either. The ability to meet density uniformity will be different on a maintenance overlay project as opposed to new construction. While density has been long regarded as the “king” of quality parameters, the bonding between layers cannot be overlooked. A thick asphalt pavement in which the surface △ continued from page 13 RETHINKING REALITY 14 FALL/WINTER 2023
layer does not have an adequate bond to the layer below will crack very quickly. The VDOT specifications in Section 310 place emphasis on tacking, and Virginia Test Methods outline the amount used and how tacking is verified. However, is this level of inspection necessary? Can random cores during or after the paving be extracted to assess bonding? Does technology exist to eliminate the need for a core? Again, how do we differentiate between a maintenance overlay (or mill/fill) and new construction? The overall uniformity of a pavement surface is generally tied to segregation. Where segregation exists, surface cracking and potholes will form and reduce the service life of the material. Segregation can start at the plant. It can be created through the loading of trucks. It can be induced by the transfer of the mix from the truck to the hopper. It can be the improper balance of the paver or operation of the augers. Or the mix getting too cold. Or a number of different causes. No matter the source, segregation is an indication of a quality issue. For some projects, the simple use of a material transfer vehicle (MTV) may minimize or eliminate segregation. Unfortunately, MTVs cannot be used in all applications or on all projects. Specific criteria must be set for projects with a surface uniformity requirement. Likewise, the owner must be thoughtful in specifying mixes for use on a project. The coarser the mix on a project where an MTV cannot be used, the greater the possibility of segregation. In current specifications, segregation is determined visually. To improve, we must move away from subjective visual assessment toward scanning technology such as lasers and cameras. Objective approaches can be used to measure and quantify segregation in an approach like density. The last quality metric that has been used in Virginia for decades is smoothness. Research conducted by McGhee and Gillespie (VTRC 06-R28) confirmed the value of smoothness in the long-term performance of pavements. Simply put, the smoother the road, the longer it will last. When the ride spec program was initiated in VDOT with inertial profilers in the early 2000s, there was no equipment and processes in place for many contractors to purchase and use the equipment for acceptance purposes. Today, the contractor can test and submit the results to the owner for payment purposes. Is it time for Virginia to move away from VDOT acceptance to validation/verification? OUR ROLE If you look closely at this sketch of a future approach, you will not see the role of the owner’s inspector present in the paving process. While a valuable part of the project delivery process for decades, retirements and workforce shortages have made this role challenging. Having a dedicated, educated, and knowledgeable inspector on every type of project is impractical. Projects are more complex than in the past. Processes followed by contractors are constantly evolving. Highly skilled inspectors are needed on those projects that are of the highest risk to the owner. Most future paving projects will rely on the contractor adhering to specifications and making appropriate field decisions to deliver quality. They will be responsible for controlling the controllables and requesting direction from the owner where the situation is beyond the contract’s scope. The owner will be responsible for a new type of inspection. You may be asking yourself, what is really new? In this case, we mean a phased inspection focused on certain criteria. At the end of a project, the three, four, or five quality metrics are measured and final payment is determined. A composite pay approach that results in a bonus, penalty, or 100% payment to the contractor. As with any major change, some aspects will take time, and others can be implemented immediately. Contractors performing ride quality testing will vary by company. Some will purchase the equipment, and others will outsource the testing to third parties. Adjusting the testing regime for asphalt mixes, however, is already underway. Bond strength can be assessed during the core/ plug density measurements, but moving to non-destructive procedures will take time and evaluation. Determining acceptable density profiles using ground penetrating radar or other technologies may take research. Surface uniformity can be evaluated using thermal cameras mounted on the back of pavers or new scanning technology on vehicles. What is clear is the approach used to monitor and accept paving projects must change. Just as past changes that were brought on by disruptors and the development of technology, tomorrow’s process will place the responsibility on the contractor to deliver what is contracted by the owner. Highly skilled inspectors will play a critical role for the owner and the contractor. Many of the details of paving projects and how decisions are made must be worked out, but they are not insurmountable. The time to start improving is now! RETHINKING REALITY VAASPHALT.ORG 15
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We all know that Virginia boasts some excellently performing pavements. Pay some attention to the roads as you travel throughout the state and you’ll see that the pavement structures were built to last. Fortunately, this practice continues with many newly designed and constructed pavements. In 2022, the Virginia Department of Transportation (VDOT) sought recognition for our state’s recent projects of significance and was awarded two Perpetual Pavement Awards (PPA) by the U.S. Asphalt Pavement Alliance (APA), one under Performance and the other under Design. As a requirement for receiving PPAs, the pavements met strict Perpetual Pavement criteria and demonstrated the characteristics expected from long-life asphalt pavements: excellence in design, quality in construction, and value for the traveling public. Perpetual by Design Recognizing the opportunity to highlight a significant project in Virginia, VDOT submitted the I-64 Widening and Reconstruction Segment II in Newport News, James City County, and York County for the PPA by Design Award, a category established in 2021. VDOT recognized the efforts taken to embrace new technologies and methods with open arms exemplified by this project, especially when compared to other states’ projects around the country. Not to mention, this project was the largest single pavement recycling project in North America at its completion. The project set for this segment of the Interstate 64 corridor was initially conceived as a reconstruction of the existing four-lane divided interstate section using jointed concrete while also adding a new travel lane David T. Lee, PE, Vice President, Virginia Asphalt Association continues on page 18 △ Perpetual Pavements SHINE IN VIRGINIA I-64 Widening and Reconstruction Segment II in Newport News, James City County, and York County, PPA by Design Award Winner. VAASPHALT.ORG 17
PERPETUAL PAVEMENTS and shoulder to the inside of the existing pavement. It was executed using full-depth reclamation (FDR) for the foundation layers and included cold central plant recycling (CCPR) as the asphalt structural layer above. The prime contractor was Allan Myers, with Slurry Pavers as the FDR subcontractor. The FDR in the existing lanes was completed by stabilizing the in-place △ continued from page 17 foundation material; while in the new lanes, the FDR stabilized imported recycled concrete aggregate. The CCPR for all lanes was produced using reclaimed asphalt pavement (RAP) from existing stockpiles and #10 aggregates, a quarry co-generated product. VDOT estimates that approximately 168,000 tons of existing stockpiled RAP was used to produce the CCPR. A study by Timm et al. (2018) estimated cost savings of approximately $10 million using the combination of pavement recycling techniques rather than traditional pavement materials. More recently, FHWA published a report (https://www.fhwa.dot.gov/pavement/ sustainability/case_studies/hif19078.pdf) on the environmental savings, which showed that these processes resulted in a significant reduction in primary energy demand and global warming potential. Therefore, not only was the project designed using Perpetual Pavement methodologies, but also notably reduced costs and environmental impact. Upon being recognized for the I-64 project, VDOT Hampton Roads District Engineer Christopher Hall, P.E. stated, “The Virginia Department of Transportation is honored to receive this national Perpetual Pavement Award for the design and delivery of top-quality pavement work as part of the 7-mile reconstruction and widening of the Interstate 64 corridor through James City County, York County, and the city of Newport News. Not only does this highlight our continued commitment to providing a long-lasting, high-quality product for an improved driving experience on the most heavily traveled corridor of the Virginia Peninsula, but also in incorporating innovative and eco-friendly approaches such as utilizing recycled materials, Cold Central Plant Recycling and Full Depth Reclamation, resulting in a significant estimated cost-savings of $10 million for the Commonwealth of Virginia. We are thankful for this recognition and hope this trailblazing approach can serve as a model to be replicated across the rest of the state and beyond.” Perpetual by Performance Many asphalt pavements function as Perpetual Pavements despite being built before the Perpetual Pavement concept began circulating in 2000. The Perpetual Pavement by Performance Award recognizes state agencies and other owners of pavements with the foresight to build pavements according to these principles. This award honors Perpetual Pavement projects that are at least 35 years old, have not suffered a structural failure, and have an average interval between resurfacing of no less than 13 years. “One of the keys to sustainability is long life,” explained Amy Miller, P.E., former I-64 Widening and Reconstruction Segment II in Newport News, James City County, and York County, PPA by Design Award Winner. PPA by Performance winner: Interstate 81 two-mile section (milepoint 109.8 to 111.8). 18 FALL/WINTER 2023
PERPETUAL PAVEMENTS National Director of the APA. “Asphalt roads can be engineered to last indefinitely with only routine maintenance and periodic surface renewal.” For the second time in recent years, VDOT’s Salem District won a PPA by Performance for a segment of Interstate 81. Most of I-81 in Montgomery County was constructed in the early to mid 1960s. This specific two-mile section (milepoint 109.8 to 111.8) was built with with 9.0" of Select Material (CBR 30), 6.0" Subbase Stone, 7.5" Base Mix Asphalt, 1.3" Intermediate Mix Asphalt, and 0.75" Surface Mix Asphalt. Despite poor subgrade and weather conditions, this section of I-81 has withstood over 56 years of heavy truck loading (103,043,000 equivalent single axle loads over its lifetime) with minimal maintenance. All one has to do is drive along Virginia’s I-81 corridor to be amazed at the performance of this roadway. Though not originally designed for the level of traffic it experiences each day, most of the corridor continues to perform at or near Perpetual Pavement standards. Ken King, P.E., Salem District Engineer spoke for the VDOT by reflecting on the honor of being selected for the APA’s 2022 Perpetual Pavement Award. “This recognizes the quality work and accomplishments of generations of VDOT and industry contributors to the pavement program in Virginia.” “Several years ago, we made a concerted effort to celebrate the past and the future of Virginia’s pavement through the perpetual pavement program,” echoed Virginia Asphalt Association President Trenton Clark. “The I-81 and I-64 projects do just that. Both are shining examples of resilience and sustainability of asphalt.” PPA by Performance winner: Interstate 81 two-mile section (milepoint 109.8 to 111.8). VAASPHALT.ORG 19
WOMEN OF ASPHALT’S 23 IN 2023 Spotlight on Virginia’s Alicia Brooks Tigre J. Fortune, Member Relations Specialist, Virginia Asphalt Association According to projections from the U.S. Bureau of Labor Statistics, the number of women in the labor force is expected to increase to 77.2 million in 2024 and make up 47.2% of the total labor force. It is important to consider the women who were driven and steadfast in entering the labor force as a minority—despite the economic downturns, recessions, and historical offsets they faced over the past decades. They paved the way for women today, and the labor force gets closer to representing equality because of it. Today’s numbers reflect that men and women can work in equal shares, and this is especially key for male-dominant sectors such as construction and asphalt. Based on a study from the Institute for Women’s Policy Research, women saw an employment percentage increase of 7% in construction jobs between February 2020 and March 2022. This percentage continues to increase year after year and, slowly closing the gender gap in our workforce. So, as more women join the workforce, what is the appeal in choosing a male-dominant industry? What value do companies gain by hiring women to work in “tough” industries like construction, infrastructure, asphalt, and engineering? These sectors have realized that their labor pool widens when they accept, if not encourage women to participate. Women also bring a fresh perspective, high competency, loyalty, innovation, and more to the workforce. VAA sat down with Alicia Brooks of KCI Technologies, Inc., a mentor and leader in the industry as well as Women of Asphalt Virginia’s Chairwoman, to hear her perspective as a woman in the asphalt and construction industry for over 20 years. VAA→ What led to your career in asphalt? What has your trajectory been since your early education days? AB→ After graduating high school in 1992, I attended Old Dominion University to become a marine biologist. Biology has always been a passion of mine. However, two years into the degree, the college changed the requirements of my goal to a five-year commitment, which seemed a bit too long and would incur more student loan debt. While sticking with the major of Biology, time and, of course, money were the deciding factors in my shifting to include a minor in Education. I began teaching until I could repay my student loans. Three years out of college, I unexpectedly became a single parent, and being a schoolteacher wasn’t a financially stable enough career choice to raise my child without any additional support. So, in the winter of 1999, I hit the newspapers and answered an ad for a nuclear gauge technician for a small family-owned asphalt company in Richmond, VA. I had no idea the job would entail testing asphalt and working in a lab. I had to interview for the position three times, as the company didn’t have the confidence that a schoolteacher would be interested or successful in maintaining longevity with an asphalt company, let alone as a nuclear gauge technician. However, despite the back and forth, I held my ground and was hired. I hit the ground running with my training and certifications. I took all the required training classes that would qualify me for testing, designing, and producing asphalt, and over 18 years, I advanced role by role within the company. I was an asphalt road technician, then a lab technician, then later a lab manager and asphalt field manager. After those roles, I oversaw the QA program and maintained the environmental permits necessary for asphalt plant operations. After leaving that company (which taught me everything I know about asphalt), I moved on to other great opportunities in the industry. Currently, I am a Construction Manager for KCI Technologies, Inc., overseeing various projects throughout Virginia, working closely with the Virginia Department of Transportation—and I still love what I do. For future generations of women in the asphalt industry, you will always have job security here. Roads will ALWAYS need building OR repairing. You can grow and shape your career in any way you want. Women of Asphalt will continue to be a voice and community for those inspired to join the industry. 20 FALL/WINTER 2023
VAA→ Throughout your career in the asphalt industry, have you faced any unfavorable experiences or challenges regarding harassment or discrimination? AB→ Unfortunately, yes. I have a list of more occurrences than I want to disclose. However, I like to think the best of people and believe that the difficult experiences I’ve endured are just meant to make me stronger. Some occurrences were followed by apologies; some were ignored and validated. I witnessed unfavorable experiences, and I think it hurts me more to see unequal treatment imposed on others who don’t or can’t stand up for themselves. I continue to strive for positive interactions that deter those behaviors, pointing them out when they occur. Across the globe, women working in male-dominant industries are more likely to experience these unfavorable occurrences, making it more difficult for women to excel in these fields, but we must continue to press on. It’s challenging, but this is why organizations like Women of Asphalt are crucial in providing women with a community of like-minded women to gather and discuss how to tackle these issues moving forward. VAA→ What is your favorite thing about the Women of Asphalt organization? AB→ The Women of Asphalt organization represents who we are and the strength of women in this industry. Even when we are the only women in the room, no matter the specific time and place— WofA stands behind us in spirit. There is strength in knowing that others like you are doing and experiencing some of the exact things in different atmospheres, and this national organization provides that strength. Being a part of this group has brought many positive aspects to my life and career. I’m excited to see the women who will come after me to continue this branch and move the organization forward for years. Being a member of Women of Asphalt Virginia has made me feel like a part of something, even during one of the most isolated times of my life. VAA→ How does it feel being recognized as one of the featured women in the Women of Asphalt “23 in 2023” campaign? AB→ This recognition leaves me feeling very flattered, humbled, and motivated. I am truly flattered that someone thought enough of me to take the time to write the nomination. I am humbled as I am included amongst the other women I have grown to admire and respect. I am motivated to continue encouraging other women and working toward a goal so that all humans can coexist and feel comfortable without gender labels or discrimination. VAA→ What are your hopes for the upcoming generation of women entering the workforce? AB→ I hope that each generation of women following in our footsteps will have less and less difficulty being understood. I hope that each generation of women will endure less of the hardships I’ve experienced and witnessed. I believe the generation before me paved the way and made it possible to have a lucrative, fulfilling career in asphalt construction. I hope our generation has built on that and fostered more acceptance of our presence. VAA→ What words of encouragement do you have for women as they view the asphalt industry as a possible career path? AB→ The words of encouragement I have for future generations of women in the asphalt industry are, you will always have job security here. Roads will ALWAYS need building OR repairing. You can grow and shape your career in any direction you want. Women of Asphalt will continue to be a voice and community for those inspired to join the industry, so I encourage these newcomers to get involved and join. WofA works hard to get in front of the next generations to uphold their mission and goals by inspiring the current and next generations as they choose their careers and enter the workforce. So, why not asphalt? Everyone is welcome here—especially women. WOMEN OF ASPHALT ALICIA BROOKS VAASPHALT.ORG 21
BACK TO BASICS Asphalt Plant Mix Segregation: Causes and Cures Greg Renegar, Chief Engineer, Astec Industries Mix segregation is a direct cause of premature pavement failure. To give an example of how this occurs, aggregate segregation is the tendency of aggregate—composed of different sizes and masses—to begin separating into groups of similar size particles. At an asphalt plant, segregation occurs most often at points where mix is transferred from one plant component to another. This results in localized areas of the road being unable to withstand the traffic or weather. In the 1980s and 1990s, segregation due to mix and equipment designs was a major problem facing the industry, but modern asphalt plants are designed to minimize segregation. This problem receives less attention today, though is still prevalent on roads worldwide. Several steps must be taken to more fully eliminate segregation at the plant level. The most common type of segregation is “end-of-load” segregation. This is typically visible to the eye, appearing as a localized area of coarser textured mix between each truckload. The coarse areas allow water to penetrate the mix and is often accurately described as the “birth of a pothole.” However, the first place to look for mix separation at the asphalt plant is the drag conveyor inlet. If more mix is on one side of the drag conveyor, there will certainly be a gradation difference across the drag flights. This mix separation must be corrected at the inlet by placing divert plate(s) at the drum outlet/drag inlet. It cannot be corrected later in the process. The second place the mix can separate is at the drag-slat conveyor discharge. This can occur as the mix falls directly into a silo batcher from the drag conveyor or a horizontal drag conveyor that carries the mix to a silo batcher. If mix separation occurs at this point, it must be addressed. Again, divert plate techniques can prevent segregation at this critical transfer point. The third transfer point for potential mix segregation is where the horizontal drag conveyor discharges into a silo batcher. The sole purpose of the silo batcher is to prevent segregation, but several important batcher rules must be followed. • It is essential for the batch size to be as large as the batcher allows. Adjust the devices or controls that determine how much mix the batcher holds. More mix in the batcher is always better. • The batcher must be loaded in the center. Any off-set loading can result in mix separation at this transfer point; that is, there will be more large aggregate on one side of the batcher. One cannot just look at the chute alignment. One must physically view the mix going into the batcher to ensure flow into the center of the batcher. • The mix going into the batcher must go straight down. There can be no horizontal component to the mix flow. Any angle to the mix flow will tend to throw larger aggregate to the far side of the batcher. Again, viewing the process directly will ensure the mix flow is vertical. Gravity Discharge Improper Truck Loading Proper Truck Loading 22 FALL/WINTER 2023
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