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Podium Presentation at the Conference, with Full Paper in Conference Proceedings

Accelerated Pavement Testing and Instrumentation

Session: AIRFIELDS - Accelerated Pavement Testing & Instrumentation

1374457 - Embedded Coil Sensors to Investigate the Deformation Behavior of Airfield Pavement Unbound Aggregate Base Courses

Friday, June 16, 2023
10:45 AM - 11:00 AM CST
Room: 400
TRACK: I
Permanent deformation, or rutting, is the primary performance indicator of an airfield flexible pavement subjected to heavy aircraft loading, where a significant portion of the total permanent deformation accumulation may originate from the rather thick unbound granular layers intended to protect the subgrade. This paper presents findings from the ongoing Construction Cycle 9 tests at FAA’s National Airport Pavement Test Facility (NAPTF) with the objective to investigate the deformation behavior trends of full-scale flexible pavement sections applied realistic traffic loading with gear/wheel load wander. Inductive coil sensor technology, which involves displacement measurements through the mutual inductance coupling of two co-axial sensors, was adopted to investigate the deformation behavior of the unbound aggregate base equipped with an array of coil sensors installed through the full depth layer profile of the unbound aggregate base. In total, 8 pairs of coil sensors were installed free-floating with a target distance of 3 in. (7.6 cm) in a 26-in. (66-cm) thick base. A dual-wheel tridem-axle (3D) gear configuration loading module applied 58,000 lbs. (26.3 tons) per wheel to the tested sections with a 6.8 ft. (2.08 m) wide wander pattern consisting of 66 passes arranged in 9 lateral wander positions. Throughout the 26,400 passes applied during the traffic testing, accumulation trends of permanent deformation with depth profile were analyzed and the depths at which minimum and maximum deformations were taking place were determined according to the 3-in. vertical intervals measured by the coil sensors. The study findings are quite revealing when the aggregate base course deformations are compared to the overall pavement surface profiles, which are intended to identify damage mechanisms in these thick airfield pavement granular layers and how thick they need to be designed and constructed to protect the subgrade.

Learning Objectives:

Attendees can expect to learn the following from this session:
  • Gather knowledge on the use of embedded coil sensors in unbound granular layers and how to take advantage this kind of instrumentation to collect responses through accelerated pavement testing
  • Demonstrate knowledge on the FAA's National Airport Pavement Test Facility (NAPTF) Construction Cycle 9 (CC9) full scale flexible pavement test section experiments slow roll and trafficking goals
  • Evaluate the coil sensor data related to the NAPTF CC9 findings, and identify governing damage mechanisms of the 26-in. thick granular base course and its permanent deformation trends