Estimation of the "C" value considered In the AASHTO-93 guide for back analysis of the elastic modulus of the subgrade

This investigation focuses on the estimation of the "C" value included in the methodology for back analysis of the subgrade elastic modulus of the AASHTO-93 Guide for Pavement Design. Within the main investigation to evaluate the behaviour of the pavement during its period of design, it emphasises The AASHTO Road Experiment, held in the United States of America in the decade of 1950s. This guide includes a methodology for back analysis of the superficial deflections using the Falling Weight Deflectometer in order to estimate the elastic modulus of the subgrade. The guide alerts about the use of this adjustment factor "C" of 0.33, considering that it responds to the pavement materials of the AASHTO Road Experiment. Hence, they recommend estimating it for each individual project, based on historical data, characteristic of the materials or laboratory test results. On this basis, this investigation compared the subgrade resilient modulus obtained from the laboratory on samples extracted from an existing road, and the modulus obtained applying the AASHTO-93 back analysis methodology. The route used for the development of the present work corresponds to 22 kilometres of the Provincial Route No 6, located in the Province of Buenos Aires, Argentina. This paper showed, based on the pavement materials that have been surveyed, that an average "C" value of 0.72 should instead be used; this is more than double of the recommended value of 0.33. This finding impacts the final result of the elastic modulus of the subgrade incrementing its value, and finally the expected structural behavior of the pavement.

• Record URL:
  • http://www.aapaq.org/documents/FPC2011/S1D3_1505_Ernesto_Urbaez_Estimation_of_C_value_AASHTO-93_back_analysis_EM_subgrade-doc.pdf
• Record URL:
  • http://arrbknowledge.com
• 
• Authors:
  • Urbaez, E
  • Giovanon, O
• Conference:
  • AAPA International Flexible Pavements Conference, 14th, 2011, Sydney, New South Wales, Australia
• Publication Date: 2011-9

Language

• English

Media Info

• Pagination: 35p (day 3, session 1)
• Monograph Title: Australian Asphalt Paving Association fourteenth international flexible pavements conference: sustainable roads, 25th - 28th September, Sydney, New South Wales, Australia

Subject/Index Terms

• TRT Terms: Backcalculation; Calculation; Deflection; Pavement design; Pavement performance; Pavement subbase
• Uncontrolled Terms: Design guide; Road design and asset management
• Geographic Terms: Argentina; Buenos Aires (Argentina)
• ATRI Terms: Back analysis; Design guide; Pavement design; Pavement performance; Subbase
• ITRD Terms: 2950: Subgrade
• Subject Areas: Highways; Pavements; I22: Design of Pavements, Railways and Guideways;

Filing Info

• Accession Number: 01375627
• Record Type: Publication
• Source Agency: ARRB
• Files: ITRD, ATRI
• Created Date: Jul 18 2012 9:26AM