Slow-Rolling Response Tests on the Test Pavements at the National Airport Pavement Test Facility (NAPTF)

Author(s):  
Gordon F. Hayhoe ◽  
Robert Cornwell ◽  
Navneet Garg
2007 ◽  
Vol 34 (2) ◽  
pp. 189-198
Author(s):  
Kasthurirangan Gopalakrishnan ◽  
Marshall R Thompson

Rutting is a major distress in airport flexible pavements. Subgrade vertical strain criteria are used in many airport flexible pavement design procedures to consider the development of rutting. Several research studies have identified the limitations associated with these criteria. Design criteria based on subgrade stress ratios (SSRs) are being considered for evaluating subgrade rutting in airport flexible pavements. In this paper, the SSRs based on measured vertical subgrade stresses are related to surface rutting in flexible pavements subjected to repeated trafficking of Boeing 777 and 747 simulated test gears at the US Federal Aviation Administration (FAA) National Airport Pavement Test Facility (NAPTF). The results indicated overstressing of the subgrade in two test sections, and this was confirmed by trench study results. A good correlation was obtained between the SSRs and the surface rut depths, supporting the validity of developing SSR-based rutting transfer functions for airport flexible pavements serving the next generation of aircraft.Key words: rutting, subgrade stress ratio (SSR), National Airport Pavement Test Facility (NAPTF), pressure cell (PC), new generation aircraft, airport flexible pavement.


Transport ◽  
2008 ◽  
Vol 23 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Kasthurirangan Gopalakrishnan

This paper presents a simplified approach for predicting the allowable load repetitions of New Large Aircraft (NLA) loading for airfield runways based on Non‐Destructive Test (NDT) data. Full‐scale traffic test results from the Federal Aviation Administration's National Airport Pavement Test Facility (NAPTF) were used to develop the NDT‐based evaluation methodology. Four flexible test pavement sections with variable (unbound layer) thicknesses were trafficked using six‐wheel and four‐wheel NLA test gears until the test pavements were deemed failed. Non‐destructive tests using a Heavy Weight Deflectometer (HWD) were conducted prior to the initiation of traffic testing to measure the pavement surface deflections. In the past, pavement surface deflections have been successfully used as an indicator of airport pavement life. In this study, the HWD surface deflections and the derived Deflection Basin Parameters (DBPs) were related to functional performance of NAPTF flexible pavements through simple regression analysis. The results demonstrated the usefulness of NDT data for predicting the performance of airport flexible pavements serving the next generation of aircrafts.


Author(s):  
Izak M. Said ◽  
Imad L. Al-Qadi

The main goal of a durable and sustainable airfield is to withstand repeated aircraft traffic loading while minimizing the environmental impact. The objective of this study is to develop a design-life cycle assessment (LCA) framework considering a balanced evaluation of structural adequacy, minimizing emission, and optimizing total energy demand. To achieve this objective, three steps are introduced: an evaluation of the structural adequacy of the design using the Federal Aviation Administration (FAA) pavement design software FAA rigid and flexible iterative elastic layered design; a preliminary performance check using field instrumentation responses; and a LCA of airfield sections using both deterministic and probabilistic approaches. In addition to presenting the design-LCA methodology, this paper offers a comparative evaluation that covers two perpetual designs (LFP1-N and LFP4-N) and one conventional section (LFC5-N). These pavement sections were built and tested at the National Airport Pavement Test Facility as part of construction cycle 7, funded by the FAA. Responses collected from instrumentation were used to compute field-based coverages to failure. Moreover, life cycle inventories from secondary sources were used to quantify the greenhouse gas emissions and energy demand associated with the construction of these sections. Results show inconsistencies between the field-predicted and theoretically predicted performance. This suggests the need for the additional calibration of the currently used performance models. Moreover, this study shows that under a specific asphalt concrete (AC) thickness limit, conventional AC may be more eco-friendly than a perpetual design.


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