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

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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.

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Correspondence to Sujata Purakayastha.

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Peer review under responsibility of Chinese Society of Pavement Engineering.

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Purakayastha, S., Biswas, P.P. & Sahis, M.K. Determination of bituminous overlay thickness of flexible pavement by mechanistic-empirical approach based on concentration factor. Int. J. Pavement Res. Technol. (2020) doi:10.1007/s42947-020-0166-1

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  • Odemark
  • Modular ratio
  • Concentration factor
  • Deflection
  • Overlay
  • Flexible pavement