Life cycle assessment applied to bituminous mixtures containing recycled materials: Crumb rubber and reclaimed asphalt pavement

This paper focuses on Life Cycle Assessment (LCA) of different types of road paving technologies based on the use of bituminous mixtures containing recycled materials such as crumb rubber from end-of-life tires and reclaimed asphalt pavement. Analyses were carried out by considering different scenarios which stem from the combination of production, construction and maintenance operations, and by comparing them with a reference case involving use of standard paving materials. LCA results, expressed in terms of gross energy requirement and global warming potential, showed that the use of rubberized bituminous mixtures produced by means of the so-called wet technology leads to significant benefits in comparison with standard paving solutions. This was proven by the reduction of both considered environmental indicators, ranging between 36% and 45%. However, these improvements are only slightly enhanced by making use in the same type of mixture of reclaimed asphalt pavement material in partial substitution of virgin aggregates. In the case of materials deriving from the alternative dry technology, no significant differences can be identified, with results that are very close to those of the standard scenario. Finally, the LCA also considered effects caused by variations of thickness and maintenance frequency for the wet technology scenarios, thus showing that their environmental effectiveness is guaranteed only by ensuring an adequate durability of the mixtures in service.