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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