APTech engineers are renowned for their leadership in prominent applied pavement research programs. Our nationally recognized team members have conducted pavement-related studies for organizations such as the Federal Highway Administration, National Cooperative Highway Research Program, Innovative Pavement Research Foundation, Airfield Asphalt Pavement Technology Program, and several state departments of transportation. The firm has played an instrumental role in large-scale, national pavement research projects as well as smaller studies for states, municipalities, and private organizations.
APTech's practical research results have been implemented by agencies across the country and around the world, providing transportation engineers with the information and tools necessary to design, build, and maintain better-performing pavements.
avement preservation is acknowledged to lead to improved pavement performance and longer pavement service lives. As such, it should be considered in mechanistic-based pavement design processes. Before 2010, the American Association of State Highway and Transportation Officials (AASHTO) interim edition of the Mechanistic-Empirical Pavement Design Guide (MEPDG) Manual of Practice did not explicitly consider the contributions of pavement preservation treatments to overall pavement performance. As a means of addressing this, the National Cooperative Highway Research Program (NCHRP) retained Applied Pavement Technology, Inc. (APTech) to provide recommendations for various approaches that could be employed to more directly consider pavement preservation as part of the pavement design process.
The approaches developed by APTech specifically recognized the benefits of pavement preservation (or preventive maintenance, in particular) to preserve an existing roadway, slow future deterioration, and maintain or improve functional condition. APTech developed a chapter on pavement preservation, in a format consistent with the AASHTO Mechanistic-Empirical Pavement Design Guide A Manual of Practice, for consideration and adoption by AASHTO. Through the successful extension of the MEPDG analysis tool to include the beneficial effects of preservation, greater acceptance of both MEPDG and pavement preservation was achieved.
Freezing and thawing causes concrete to expand and contract, creating damage. To prevent this problem, microscopic air bubbles are purposefully entrained in the concrete to act as tiny pressure relief valves that dissipate stress as saturated concrete freezes. However, if excessive air is entrained in concrete, there is a commensurate loss of strength and an increase in permeability, both of which negatively affect the durability of concrete. The optimal mix of concrete and air minimizes freezing damage and maximizes strength. The Wisconsin Department of Transportation (DOT) has recognized the need to evaluate the impacts to the air void structure and air content due to the vibration and consolidation action of today’s modern slipform pavers used in Wisconsin. APTech was selected to develop performance-related specifications to determine the optimal mix of concrete and air for slipform pavers.
This project involved investigating the effects of concrete mixture components (air-entraining admixture and aggregate type), concrete plant type, and concrete paver type on the characteristics of the entrained air-void system. These goals were accomplished through conducting a literature review, developing a testing matrix, conducting field and laboratory investigations, and preparing a report of the findings. The final goal of the research was to evaluate the impacts of slipform paving on the air-void parameters of portland cement concrete pavements and help identify appropriate air content target values to ensure that in-place concrete meets or exceeds desired properties in regards to strength and air.
Alberta Infrastructure and Transportation (INFTRA) used the 1993 American Association of State Highway and Transportation Officials (AASHTO) Guide for Design of Pavement Structure for design of new and overlay pavements. INFTRA’s Pavement Design Manual documented its current pavement design approach using the 1993 AASHTO Guide, but several areas needed modification, including the use of drainage and material layer coefficient values. The coefficients had been in use since the implementation of the Pavement Design Manual in 1997, but the introduction of new materials and evaluation techniques raised questions about their applicability. Consequently, APTech reviewed and verified the drainage and material layer coefficients, recommending changes as appropriate.
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