Beneficial use of recycled aggregates from concrete sludge using a new dry washing technology

Abstract

Demands for a more sustainable concrete production with reduced waste streams and lower carbon footprint has introduced new solutions that transform waste streams into recyclable raw materials and bring them back into the value chain. Here, recycled aggregates with carbonation potential from a dry-washing technology for concrete trucks are considered to reduce concrete waste. Accordingly, the environmental impacts of a dry-washing method in ready-mix concrete production were investigated through a scenario-based attributional life cycle assessment (LCA) approach. The environmental impacts are calculated by a cradle-to-gate LCA modelling in SimaPro® based on onsite interviews in Norway, existing environmental product declarations (EPD), and geography-specific life cycle inventory data. Also, the properties of the reclaimed aggregates have been tested to ensure their mechanical strength for use in fresh concrete. LCA showed that the dry-washing method reduces environmental impact compared to the conventional handling of concrete sludge. The technology reduces the concrete sludge by > 80% thereby reducing the treatment of washing water. Using recycled aggregates decreases the extraction of virgin aggregates. The study contributes to circularity in the production design of concrete by controlling the material and waste flow in the life cycle of concrete.