Characterization of NAPTF subgrade soils for mechanistic-based analysis and design of airport flexible pavements

Abstract

The National Airport Pavement Test Facility (NAPTF) was constructed to generate full-scale testing data to support the development of advanced airport pavement design procedures. The NAPTF material properties were characterized using test pit data obtained prior to full-scale heavy gear trafficking as well as using test data obtained from trenches opened after the completion of traffic testing. In this paper, the post-traffic subgrade characterization test results obtained from NAPTF subgrade trench sections were evaluated and compared with the pre-traffic test pit data. The combined data were used to evaluate the most commonly used correlations amongst subgrade soil properties. Subgrade moduli backcalculated from Heavy Weight Deflectometer (HWD) test data were compared with the laboratory test results and were also correlated to field California Bearing Ratio (CBR) values. Regression analyses indicated that subgrade resilient modulus is significantly related to the unconfined compressive strength. These results may be used in the mechanistic-based analysis and design of airport flexible pavements subjected to New Generation Aircraft (NGA).