Study on the use of bituminous mixtures modified with acrylic fibres in road pavement overlays

In general, fibres can be used to improve the mechanical properties of bituminous mixtures in road pavements. Fibres may be used as additives to modify bituminous mixtures by fastening a significant amount of bitumen, what allows the increase of the binder content of the mixtures without losing their resistance to permanent deformation. Thus, fibres are a valuable additive for mixtures containing a high quantity of mastic, such as Stone Mastic Asphalt (SMA). Actually, bituminous mixtures modified with fibres emerge as an excellent solution to be applied on thin overlays used over cracked pavements. The high quantity of bitumen in the mastic of these mixtures guarantees a significant resistance to the initiation and propagation of fatigue and reflective cracking, what, associated with the stability offered by fibres, produces a material with an excellent performance, mainly in road pavement overlays. The main objective of this paper consists in evaluating the advantages of using acrylic fibres in bituminous mixtures, by studying their main properties in laboratory which are compared with those of mixtures usually applied in road overlays. By using a FEM numerical simulation, this paper also estimates the required thickness to overlay an existent cracked pavement with traditional dense mixtures or with mixtures modified with fibres