Over the past several years, the Laboratorio de Caminos de la Universidad Politecnica de Cataluna has been researching and working on the crack reflection problem in roadbase layers treated with hydraulic binders on the rolled bituminous layers. By way of a finite elements program, which introduces a continuous damage model in its constitutive equations, we have analysed the influence of the different parameters of the mixture: modulus, resistance to traction,toughness, etc. on the resistance of the asphalt rolling layers to the propagation of cracks, as well as the effect of interlocking crack-resistant layers. At the same time, laboratory tests have been carried out to develop asphaltic compounds, or bituminous mixes with large synthetic fibres (12-20 mm) which are characterized by their toughness and resistance to cracking. For the characterization and study of these new materials, a new testing procedure has been established, known as the BTD test, which allows for a quick and simple simulation of crack propagation in the laboratory. With this test, we selected a series of formulae which have been successfully used to reinforce semi-rigid road surfaces with crack reflection. This paper presents the results of the analytical study carried out on this crack reflection phenomenon, where the determining factors of this phenomenon are analysed, and its incidence on the speed of crack propagation. Likewise, laboratory results corresponding to asphaltic compounds are included, highlighting the advantages provided by these materials on standard mixes to eliminate or delay the crack performances achieved with this new material are included as well as the results obtained. (A)
Abstract