Life cycle assessment of natural and mixed recycled aggregate production in Brazil

Abstract

The natural and mixed recycled aggregate production for use as road base and subbase have been compared through an attributional life cycle assessment. The primary data have been collected in a basalt natural aggregate production facility and in a recycling facility of mixed aggregate, both located in Southeast Brazil. The topic is important since there is a local increasing demand for aggregate use in road construction and there are no studies related to the environmental aspects of the production of natural and mixed recycled aggregate, and no suitable, site-specific data are available to develop a reliable life cycle investigation. The potential environmental impacts related to the two production processes have been estimated by using the Impact 2002+ methodology. The results show that the production of recycled aggregates is preferable to that of natural materials for the impact categories of “respiratory inorganics”, “terrestrial ecotoxicity”, “land occupation”, “global warming” and “non-renewable energy”. A specific sensitivity analysis suggests that the mixed recycled aggregate is a better option for all the environmentally impact categories if the distance of the recycling facility from the consumer is up to 20 tkm longer than the distance of the natural aggregate production facility from the consumer of this product. These results, and those of the detailed life cycle inventory and impact assessment, may support the decision making process in the same field as well as the development of similar life cycle assessment studies, provided that both be appropriately adapted to the specific conditions of the system under analysis.