Rehabilitation of roads containing cobblestone pavements covered with a bituminous layer

Historically, many roads in Belgium were constructed using cobblestones. In the past, cobblestone roads used by a limited amount of heavy traffic were sometimes covered with a bituminous layer. For numerous reasons it is often recommendable to replace the cobblestones when rehabilitating these roads. With their low budget or for urgent interventions, road managers sometimes prefer replacing the bituminous layer by a new one. One approach for the evaluation of structure rehabilitation was in use in Belgium since the late 1970ies and consists of the computation of a theoretical single layer model equivalent to the existing multilayer structure. Based on traffic expectations and an abacus of life-time expectations of a standard road structure, the optimal thickness of a bituminous overlay can be estimated. When the existing multilayer structure contains a cobblestone layer, the main difficulty with this approach arises from the choice of the "equivalence factor" for the cobblestone layer. When using back-calculation software, the main difficulty encountered is the choice of realistic parameters modelling the cobblestone layer. Values for parameter s such as the layer thickness, the Poisson coefficient of the material, the degree of bounding with the other layers, and the initial guess for the E-modulus of the layer have to be introduced in the software for the cobblestones. Once the back-calculation delivered E-moduli for all layers in the introduced road structure model, a direct computation can estimate life-time expectance after repairs or the appropriate rehabilitation of the existing structure for a considered future traffic load. Both approaches were used and compared in real cases of rehabilitation design. In this contribution the limitations of road rehabilitation conserving a cobblestone layer below the surface layer will be discussed. Examples will illustrate the difficulties experienced when trying to estimate bearing capacity from FWD measurements and how they were dealt with.

Language

  • English

Media Info

  • Pagination: pp 983-992
  • Monograph Title: Bearing capacity of roads, railways and airfields: proceedings of the ninth International Conference on the Bearing Capacity of Roads, Railways and Airfields: Trondheim, Norway 25-27 June 2013. Vol 1-2

Subject/Index Terms

Filing Info

  • Accession Number: 01596594
  • Record Type: Publication
  • Source Agency: Swedish National Road and Transport Research Institute (VTI)
  • ISBN: 9788232102853
  • Files: ITRD, VTI
  • Created Date: Apr 21 2016 12:36PM