Asphalt mixtures modified with basalt fibres for surface courses

This paper shows the results of an experimental study concerning the effect of introduction of basalt fibres in asphalt mixtures for surface course, mainly with regard to those to be used in urban areas, for dedicated bus lanes. Surface layers, where tire-pavement interactions occur, have to provide different properties such as high friction (very important for users’ safety), stability, resistance to meteorological agents, and contribution to the overall pavement performances. Considering that basalt fibres provide considerable physical and mechanical properties and above all high abrasion resistance, scope of the study is to evaluate the effects of these fibres on mixtures properties, especially in terms of friction and rutting behaviour. For this purpose, after setting up a model to estimate the impact of fibres on asphalt film thickness and richness modulus, the mixtures produced were subjected to laboratory tests for performance evaluation in terms of rutting resistance and the surface texture. The test results allow drawing some important conclusions about basalt fibre-modified asphalt mixtures: in particular, these mixtures show better performance with reference to permanent deformation resistance when compared with the traditional mixture; moreover, the introduction of basalt fibres involves a “flattening” of the profile texture and a lower macrotexture. Interestingly, fibres addition is likely to slightly increase the micro-texture. This point calls for further study.