Tar-containing reclaimed asphalt – Environmental and cost assessments for two treatment scenarios

Life Cycle Assessment analysis was carried out in order to evaluate quantitatively the environmental burdens related to two possible treatment scenarios for tar-containing reclaimed asphalt pavements. About 4500 tons of this hazardous waste material was obtained during the reconstruction of the runway at Ljubljana Airport. According to the first scenario, this material could be transported to a suitable incineration plant where the hazardous compounds would be decomposed. According to the second scenario, it could be treated as a recycled aggregate, and used for the production of lean concrete for different civil engineering applications, in which case 40 wt. % of the natural aggregates would be replaced by reclaimed asphalt. The hazardous PAHs would be immobilised in the concrete. The results of LCA analysis showed that the incineration scenario has an especially significant impact on energy consumption, as well as on Abiotic Depletion Potential and Global Warming Potential. The reason for this can be found in the energy needs at the incineration plant for the maintenance of high combustion temperatures, since the net generation of energy is low during the incineration of low calorific reclaimed asphalt. In the case of the recycling scenario, the results of the study showed only a slight burden or even a benefit for all of the studied environmental indicators. This is a direct consequence of the reduced extraction and production of natural aggregate. The study also showed that around 1.5–2 EUR can be saved for each ton of reclaimed asphalt in the case of recycling scenario.