Simulation of Flexible Pavement Design in Kansas
The Kansas Department of Transportation (KDOT) is currently adopting the Mechanistic-Empirical Pavement Design Guide (MEPDG) to replace the 1993 American Association of State Highway and Transportation Officials (AASHTO) design method. It would be valuable for the designer to know whether the MEPDG design simulation analysis would predict the actual distresses observed in Kansas. Thus, five newly built Superpave pavements, designed using the 1993 AASHTO design guide, were selected as test sections for the design-simulation study. Deflection data were collected approximately 8 to 10 weeks after construction using a falling-weight deflectometer (FWD). The FWD deflection data were used to backcalculate the pavement-layer moduli using three different backcalculation programs. All mixture data were obtained from the KDOT mix-design database. Required parameters for use in asphalt concrete (AC) mixture modulus prediction equation were then calculated. The existing pavement structures were analyzed for a 10-year analysis period. The maximum numbers of years the existing pavement structures will be in a serviceable condition as well as the minimum thicknesses of different layers to serve for ten years were determined. Effects of changing subgrade modulus, target distress, and reliability were also investigated. The MEPDG design analysis shows that the 1993 AASHTO guide-designed flexible pavements do not show the distresses currently observed in Kansas for the 10-year design period. Thus, local calibration of the design models appears to be essential. The MEPDG design simulation shows that the thinner the pavement sections, the higher the AC layer and total permanent deformation. The existing pavement structures can serve for more than 20 years as per the MEPDG design analysis if the default failure criteria and nationally calibrated models are used. The total AC thickness varies from 3 to 6 inches for a 10-year design period if the effect of AC surface-down cracking (longitudinal cracking) is ignored. The lowest thickness is observed on a pavement that has 11 inches of aggregate base. The minimum total AC thickness to serve for a 10-year period, considering the longitudinal cracking, varies from 6 to 9 inches. The lowest International Roughness Index (IRI) is observed on a pavement that has the highest total AC thickness and vice versa. Longitudinal cracking does not depend on the thickness of AC layers. Backcalculated subgrade moduli obtained from various backcalculation programs result in variable predicted distresses for different projects. Distress target values and reliability do not show significant effects on the maximum service life of the existing pavements. Verification of these results by the in-service pavement performance is recommended.
- Record URL:
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Corporate Authors:
Iowa State University, Ames
Institute for Transportation
Ames, IA United States 50010-8664 -
Authors:
- Gedafa, Daba S
- Hossain, Mustaque
- Romanoschi, Stefan A
- Gisi, Andrew J
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Conference:
- 2009 Mid-Continent Transportation Research Symposium
- Location: Ames Iowa, United States
- Date: 2009-8-20 to 2009-8-21
- Publication Date: 2009
Language
- English
Media Info
- Media Type: Web
- Features: References; Tables;
- Pagination: 14p
- Monograph Title: Proceedings of the 2009 Mid-Continent Transportation Research Symposium
Subject/Index Terms
- TRT Terms: Asphalt concrete; Backcalculation; Falling weight deflectometers; Flexible pavements; Mix design; Pavement design; Pavement distress; Subgrade (Pavements)
- Identifier Terms: Mechanistic-Empirical Pavement Design Guide
- Geographic Terms: Kansas
- Subject Areas: Highways; Pavements; I22: Design of Pavements, Railways and Guideways;
Filing Info
- Accession Number: 01139777
- Record Type: Publication
- Files: TRIS
- Created Date: Sep 18 2009 7:07AM