Developing A Fair Specification for Paver Mounted Thermal Profiling

High quality pavement construction improves long-term pavement performance. State Departments of Transportation (DOTs) use laboratory and field tests throughout various stages of a construction contract to measure properties related to asphalt mixture and mat performance. By assessing the quality of asphalt mixtures and placement practices before and during paving operations, DOTs can make informed decisions regarding conformance to specifications. Asphalt mat density is an important volumetric property that has a direct impact on long-term performance and is correlated to performance properties of the mat (tensile strength, stiffness, fatigue strength, etc.). Many state DOTs, such as Ohio, include asphalt mat density as a quality characteristic in their Quality Assurance (QA) program and use it as a payment factor for contractors. In-place density is an important indicator of a pavement's potential for "segregation," or nonuniform zones of mix, which are typically lower in density than the rest of the Hot Mix Asphalt (HMA) mat. The usual form of HMA segregation is truck-end segregation which occurs where the HMA at the ends of the truckload is colder and sometimes coarser in gradation. These locations show up on the mat as regularly spaced defects and can vary from small areas on either side of the paver to larger areas that extend across the width of the HMA mat being placed. The segregated locations deteriorate rapidly because of their lower density, higher permeability, and higher susceptibility to raveling and fatigue cracking. These locations can fail prematurely, causing poor ride quality for the traveling public and a burden of unplanned maintenance costs for the agency. Paver Mounted Thermal Profiling (PMTP) provides thermal mapping of asphalt mats during the laydown process. This information is especially useful for managing the laydown process and controlling the quality of the final product, specifically final pavement density and segregation. The main goal of this project is to provide innovative recommendations for a fair specification for paver mounted thermal profiling. Specific objectives include the following: (1) gain an in-depth understanding of the effective pavement temperature differentials; (2) during construction affect specified standards and life-cycle performance; (3) apply innovative AI and ML techniques to finding the optimal use of available data and inform future data collection/analysis protocols; and (4) develop a fair and executable specification for employing PMTP technology to ensure the quality of flexible pavement construction. The results of this research will provide recommended parameters for a specification that could augment current quality assurance protocols. By using advanced data science techniques to delineate the relationship between PMTP data and pavement performance, ODOT will have the tools to employ targeted coring that will be more likely to identify issues and strengthen existing incentives and disincentives for contractors.