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.