Matching Items (2)
Description
The structural design of pavements in both highways and airfields becomes complex when one considers environmental effects and ground water table variation. Environmental effects have been incorporated on the new Mechanistic-Empirical Pavement Design Guide (MEPDG) but little has been done to incorporate environmental effects on airfield design. This work presents a developed code produced from this research study called ZAPRAM, which is a mechanistically based pavement model based upon Limiting Strain Criteria in airfield HMA pavement design procedures. ZAPRAM is capable of pavement and airfield design analyses considering environmental effects. The program has been coded in Visual Basic and implemented in an event-driven, user-friendly educational computer program, which runs in Excel environment. Several studies were conducted in order to insure the validity of the analysis as well as the efficiency of the software. The first study yielded the minimum threshold number of computational points the user should use at a specific depth within the pavement system. The second study was completed to verify the correction factor for the Odemark's transformed thickness equation. Default correction factors were included in the code base on a large comparative study between Odemark's and MLET. A third study was conducted to provide a comparison of flexible airfield pavement design thicknesses derived from three widely accepted design procedures used in practice today: the Asphalt Institute, Shell Oil, and the revised Corps of Engineering rutting failure criteria to calculate the thickness requirements necessary for a range of design input variables. The results of the comparative study showed that there is a significant difference between the pavement thicknesses obtained from the three design procedures, with the greatest deviation found between the Shell Oil approach and the other two criteria. Finally, a comprehensive sensitivity study of environmental site factors and the groundwater table depth upon flexible airfield pavement design and performance was completed. The study used the newly revised USACE failure criteria for subgrade shear deformation. The methodology utilized the same analytical methodology to achieve real time environmental effects upon unbound layer modulus, as that used in the new AASHTO MEPDG. The results of this effort showed, for the first time, the quantitative impact of the significant effects of the climatic conditions at the design site, coupled with the importance of the depth of the groundwater table, on the predicted design thicknesses. Significant cost savings appear to be quite reasonable by utilizing principles of unsaturated soil mechanics into the new airfield pavement design procedure found in program ZAPRAM.
ContributorsSalim, Ramadan A (Author) / Zapata, Claudia (Thesis advisor) / Witczak, Matthew (Thesis advisor) / Kaloush, Kamil (Committee member) / Arizona State University (Publisher)
Created2011
Description
Differences in climatic conditions, aircraft traffic, and maintenance practices drive airfield pavements to perform differently. Through the Federal Aviation Administration’s (FAA’s) PAVEAIR online database and the National Oceanic and Atmospheric Administration’s (NOAA’s) online public platform, historical pavement condition and climate data from nearly 200 airfields in the dry freeze (DF), dry no-freeze (DNF), wet freeze (WF), and wet no-freeze (WNF) climatic regions were collected to evaluate pavement performance and distress trends. This research details the methodologies employed in the PAVEAIR pavement inspection data retrieval and dataset organization, and further presents the results of a two-part analysis. First, rate of deterioration (ROD) of various pavement families were evaluated by fitting a linear regression to the pavement condition index (PCI). Then, historical distresses data were analyzed for various pavement families in the different climatic regions. Families were assigned with respect to climate, pavement structure (conventional asphalt or asphalt overlays), and branch type (apron, taxiway, and runway).
The regression results showed that pavements in the WF region have the highest ROD, followed by the pavements in the DNF region. In terms of branch type, in three of four climatic regions, aprons have the fastest rate of deterioration, followed by taxiways and runways, respectively. The distress analytics revealed that cracking type of distresses were the most common in all the regions regardless of the pavement family.
The results showed that climatic data alone were not adequate to characterize airfield pavement behavior due to the multivariate factors affecting pavement deterioration. An accurate pavement and distress prediction modeling effort should at least include additional information on the structure and traffic level.
ContributorsDuah, Ebenezer (Author) / Ozer, Hasan (Thesis advisor) / Kaloush, Kamil E (Committee member) / Mamlouk, Michael S (Committee member) / Arizona State University (Publisher)
Created2021