Promotion of bitumen-impregnated cellulose fibres from lightweight roofing tiles in stone mastic asphalt

Applied in wearing courses, Stone Mastic Asphalt (SMA) is known to enhance pavement durability, in particular to reduce permanent deformation. The peculiarities of this bituminous mixture consist of its high content of coarse aggregates, its gap-graded gradation and the presence of fibres inside. Traditionally, cellulose fibres extracted from different sources (paper, magazines) are employed. In this research work, bitumen-impregnated cellulose fibres made according to the same manufacturing process as for lightweight roofing tiles were used. These materials are composed of a soft pure bitumen, recycled magazines and old corrugated paper (OCC). The objective of this study was to evaluate the influence of their introduction on the compactability, volumetric and mechanical properties of SMA mixtures. The results showed that adding impregnated fibres decreases binder drainage. Moreover, incorporating a specific fibre content of 0.3% wt. improves compactability, compression and rutting resistances of the mixtures. As a conclusion, bitumen-impregnated cellulose fibres similar to those used in roofing industry are viable for a potential use in SMA.