Life Cycle Assessment of Asphalt Pavements Using Crumb Rubber: A Comparative Analysis

Using crumb rubber (CR) as a performance enhancing additive to asphalt
mixtures is an increasingly popular method to improve pavement properties and
recycle waste tires. However, the ecological benefits/losses of CR asphalt pavements
have not yet been assessed in Switzerland. This study investigates the climate change
impacts and cumulated energy demand as two indicators of environmental impacts
for CR modified wearing courses in Swiss semi dense asphalt pavements. Mechanical
tests are conducted to estimate the lifetime of wearing courses. CR comes from the
waste tires otherwise incinerated in cement kilns. Life cycle assessment is employed
to compare the environmental impacts of scenarios with varying amounts of CR use
(from waste tires) in pavements and the current situation of conventional pavements
and co-processing of waste tires in cement kilns. Inventory data are collected from
previous scientific works, reports, industrial partners and the ecoinvent v3.5 database.
The results show that the CR wearing courses have comparable energy demands to
conventional pavements, while emitting less greenhouse gases compared to the reference system that is polymer modified. It can be preliminarily concluded that using CR
in the SDA wearing course of pavement is a potentially environmentally promising
option compared to conventional materials to enhance pavement performance, and
it provides a viable option to recycle waste tires in Switzerland.