Design after Back-Calculating K-Value with HFWD

Determination of subgrade strength for rigid pavements, i.e. k-value, is an important factor for the design of pavements. Various design manuals and practices suggest that the k-value should be determined by a plate bearing test at the natural subgrade. This value should be corrected for any stabilizing layer or other material laid over the subgrade (i.e., subbase course and base course) for pavement design purposes. This corrected k-value is thus used as an effective k-value by various designers. The Aerodrome Design Manual of ICAO suggests that plate bearing tests conducted on top of subbase courses can sometimes yield erroneous results, since the depth of influence beneath a 762 mm bearing plate is not as great as the depth of influence beneath a slab loaded with an aircraft landing gear assembly. In this instance a subbase layer can influence the response of a bearing plate more than the response of a loaded pavement. Some literature recommends an effective static k-value of one-half of the effective dynamic k-value, where the k-value back calculated by a falling-weight deflectomer (FWD) is considered as the dynamic k-value. In order to establish a relation between dynamic and static k-values in Indian conditions, plate load tests were conducted at many places at different airports on natural subgrade, on subsequent subbase and base course layers, and these were verified with designed k-values for individual layers. Further, the k-value achieved by heavy falling-weight deflectometer (HFWD) back-calculation after collection of deflection data on finished concrete pavement at the same locations was also compared. It was observed that in most of the cases the k-values calculated by HFWD readings were very close to the design k-value at the top of the base course (underneath the concrete slab) as well as those worked out with plate load tests. Therefore, it is recommended that the k-values calculated by HFWD data can suitably be used as input for overlay design.

• Record URL:
  http://www.airporttech.tc.faa.gov/Airport-R-D/Conference-and-Workshop/Airport-RD-Conference-Detail/dt/Detail/ItemID/399/Design-after-Back-Calculating-k-value-with-HFWD
• Record URL:
  http://www.airtech.tc.faa.gov/naptf/att07/2007/Papers/P07012_Chaudhari&Gupta.pdf
• 
• Corporate Authors:

  Federal Aviation Administration

  800 Independence Avenue, SW
  Washington, DC  United States  20591
• Authors:
  • Chaudhari, G K
  • Gupta, Pankaj
• Conference:
  • 2007 Worldwide Airport Technology Transfer Conference
  • Location: Atlantic City New Jersey, United States
  • Date: 2007-4-16 to 2007-4-18
• Publication Date: 2007

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 12p
• Monograph Title: 2007 FAA Worldwide Airport Technology Transfer Conference: New Directions in Airport Technology

Subject/Index Terms

• TRT Terms: Backcalculation; Coefficient of subgrade reaction; Falling weight deflectometers; Flexural strength; Pavement design; Subbase (Pavements); Thickness
• Uncontrolled Terms: Heavy weight deflectometers
• Geographic Terms: India
• Subject Areas: Aviation; Design; Pavements;

Filing Info

• Accession Number: 01617393
• Record Type: Publication
• Files: TRIS, ATRI, USDOT
• Created Date: Nov 21 2016 1:43PM