Determination of bituminous overlay thickness of flexible pavement by mechanistic-empirical approach based on concentration factor

  • Sujata PurakayasthaEmail author
  • Partha Pratim Biswas
  • Manoj Kumar Sahis
Article in Press


In this paper, attempts are made to formulate a methodology for determination of bituminous overlay thickness of flexible pavement by mechanistic-empirical approach based on concentration factor. The term concentration factor in this paper has been defined as a factor, which is used for determination of vertical stress by Boussinesq’s theory in a two layered system. An analytical approach for determination of concentration factor has been presented in this paper for different modular ratio defined as the ratio of elastic modulus of top and bottom layer in a two layered system. The elastic modulus of in-service pavement has been obtained by back-calculation from rebound surface deflection which has been used for determination of modular ratio. In this paper, the vertical interface stress and corresponding deflection in a two layered system has been determined for an estimated modular ratio with required overlay thickness of specified resilient modulus so that the interface deflection becomes equal to the allowable deflection for design axle load repetitions as recommended by Asphalt Institute. In this backdrop, required thickness of bituminous overlay has been obtained by solving the proposed equation using back-calculation technique by Odemark’s method. Comparative analysis of the results obtained from the present study with the findings of the Indian Road Congress (IRC) shows reasonable convergence in different load ranges.


Odemark Modular ratio Concentration factor Deflection Overlay Flexible pavement 


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  1. [1]
    Asphalt Institute, Asphalt overlays for highway and street rehabilitation. Manual Series (MS)–17. AI, Lexington, KY, USA, 1996.Google Scholar
  2. [2]
    Indian Road Congress, Guidelines for strengthening of flexible road pavements using Benkelman beam deflection technique. IRC: 81. New Delhi, India, 1997.Google Scholar
  3. [3]
    W. R. Kinchen, H. W. Temple, Asphaltic concrete overlays of rigid and flexible pavements. Research Report No. FHWA/LA-80/147, Research Project No. 69-3B. Louisiana Department of Transportation and Development, Federal Highway Administration, LA, USA, 1980.Google Scholar
  4. [4]
    S. M. Hoffman, Direct method for evaluating structural needs of flexible pavements with Falling-Weight Deflectometer deflections, Transp. Res. Rec. 1860 (1) (2003) 41–47.CrossRefGoogle Scholar
  5. [5]
    E. Horak, Application of Equivalent-Layer-Thickness concept in a mechanistic rehabilitation design procedure, Transp. Res. Rec. 1207 (1988) 69–75.Google Scholar
  6. [6]
    Z. Soos, C. Toth, Simple overlay design method for thick asphalt pavements based on the Method of Equivalent Thicknesses, Periodica Polytechnica Civ. Eng. 61 (3) (2017) 389–397.Google Scholar
  7. [7]
    Oregon State Highway Division, Flexible pavement design procedure, Oregon Department of Transportation, Oregon, USA, 1951.Google Scholar
  8. [8]
    H. Zhou, J. Huddleston, J. Lundy, Implementation of back calculation in pavement evaluation and overlay design in Oregon, Transp. Res. Rec. 1377 (1992) 150–158.Google Scholar
  9. [9]
    N. Odemark, Investigations as to the elastic properties of soils and design of pavements according to the theory of elasticity. No. Meddelande 77. Statens Vaginstitut, Stockholm, Sweden, 1949.Google Scholar
  10. [10]
    P. Ullidtz, Modelling flexible pavement response and performance, Lyngby, Polyteknisk Forlag, Denmark, 1998.Google Scholar
  11. [11]
    P. P. Biswas, Mechanistic–Empirical design of bituminous pavement using concentration factor in a two layered system, (PhD thesis), Jadavpur University, Kolkata, India, 2005.Google Scholar
  12. [12]
    K. Xia, A finite element model for tire / pavement interaction: application to predicting pavement damage, Inter. J. Pave. Res. Technol. 3 (3) (2010) 135–141.Google Scholar
  13. [13]
    Indian Road Congress, Guidelines for the design of flexible pavements. IRC-37. New Delhi, India, 2018.Google Scholar
  14. [14]
    R-6 Research Scheme, Development of methods such as Benkelman Beam Method for estimation and design of overlays for strengthening of weak pavements. Final report submitted to the Ministry of Surface Transport (Roads Wing) by the Central Road Research Institute, New Delhi, India, 1995.Google Scholar

Copyright information

© Higher Education Press Limited Company 2020

Authors and Affiliations

  • Sujata Purakayastha
    • 1
    Email author
  • Partha Pratim Biswas
    • 1
  • Manoj Kumar Sahis
    • 1
  1. 1.Department of Construction EngineeringJadavpur UniversityKolkataIndia

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