title: Assessment of Pavement Classification Number of Airport Pavements Based on Falling Weight Deflectometer Test
Creators: name: Sun, Junyu
Publisher: name: Griffith University
Year: 2023
Subjects: subject: Airport Pavement Management System
subject: Pavement Structural Evaluation
subject: Heavy Weight Deflectometer
subject: Maintenance and Rehabilitation

description: Asphalt and concrete pavements are widely constructed for airport runways, taxiways, and aprons to support aircraft traffic loads for a specified design life. The pavement structural configuration, materials, aircraft traffic, environmental conditions, and pavement failure model should be considered in the design stage of airport pavements, before construction. Different stress distributions at interfaces of pavement structural layers are developed in the two main types of pavement structures (rigid and flexible pavements), because they support traffic load in different ways. Airport pavement structural design differs greatly from road pavement structural design, because of the following characteristics of the former: high traffic load, high load magnitude, high tyre pressure, and high traffic wander. Computer programs based on the specifications of airport pavement structural design have been developed to assist engineers in designing pavement structures. The main methods used by the programs are empirical methods, analytical design charts, and numerical approaches (layered elastic analysis and finite element analysis). The Federal Aviation Administration (FAA) and other agencies' methods of structural design and the corresponding design programs were reviewed in this thesis, which also discussed their computational methodology and identifies advances in pavement structural design methods. Pavement structural condition can be evaluated by falling weight deflectometer (FWD) or heavy weight deflectometer (HWD) tests, which simulate the stress generated by a moving aircraft. From such nondestructive testing (NDT), the load-carrying capacity and remaining life of an existing pavement can be determined. This information supports design of maintenance and rehabilitation (M&amp;R) strategies. Airport traffic should also be considered during the design stage of airport pavements, before construction. To protect airport pavements from unexpected overload, a pavement strength rating system and an aircraft load classification system are used. Under the rating systems developed by the International Civil Aviation Organization (ICAO), the Aircraft Classification Number (ACN) and the Pavement Classification Number (PCN) are calculated to assess aircraft loads and the load-carrying capacity of airport pavements for unrestricted operations. With the ongoing increase in air-traffic demand, increasing attention to the continuous evaluation of airport pavement conditions is being introduced to airports worldwide. Evaluation of the load-bearing capacity and continuous calculation of PCN during the pavement service life is used to assess airport pavement conditions. PCN values can be estimated by testing the response of stationary dynamic loads, using a FWD or a HWD device that simulates the stress generated by aircraft movements. By evaluating the PCN continuously in Airport Pavement Management Systems (APMS), periodic determinations of the load-bearing capacity can be conducted to support M&amp;R decision-makers. Accurate evaluation of the elastic moduli of structural layers is essential when evaluating the condition and load-bearing capacity of an airport pavement. The generation of pavement surface deflection basins by FWD or HWD test has been widely applied as an NDT approach to analyse the elastic moduli of the pavement layers via a back-calculation procedure. The accuracy of the back-calculated modulus depends on the accuracy of the input layer properties as well as the back-calculation process, including the forward calculation step and the iteration procedure. The research reported here looked at the different tools and methodologies for analysing FWD and HWD test results, using data from the FAA's National Airport Pavement Test Facility’s HWD "Round-Up" tests. The equivalent thickness method and the layered elastic analysis employed by different back-calculation tools were compared, based on the back-calculation results for both rigid and flexible pavement sections. Furthermore, a comparative study of the back-calculation process of the rigid and flexible pavement sections was implemented to elucidate the factors influencing the back-calculation results of different pavement types. The findings show that the application of the back-calculation analysis is effective and provides a comprehensive and state-of-the-art structural evaluation approach for airport pavements. This study also examined the effect of different damage criteria of pavement materials and different HWD drop load levels on PCN calculation results, based on HWD test data and the use of a technical method for determining PCN. Data from a flexible pavement and a rigid pavement constructed by the National Airport Pavement Test Facility were used for calculation of PCN based on the HWD test data under three drop loads: 50 kN, 100 kN, and 150 kN.