Recycled concrete for foundation structure: LCA case study

Abstract

Concrete containing primary raw resources such as sand and gravel can be replaced by recycled aggregate concretes (RAC). But recycling processes are energy-consuming and thus energy resources are consumed. To investigate the resource consumption and overall environmental impact related to the life cycle of RAC, Life Cycle Assessment (LCA) was used to compare ten RAC foundation structures with two foundation structures containing just natural aggregate (NA). This paper presents the characteristics of two types of RAC for the foundation with various replacement rates of NA (30%, 50%, 100%). Various concrete mixtures were designed with the three replacement ratios of natural gravel, the two amount of cement and the two effective water-cement ratios. Unsurprisingly, the NA foundation structures have smaller crude oil consumption. The NAC I 16/20 foundation consumed 84 kg of crude oil. Contrarily, this foundation has the biggest consumption of natural aggregate (7.6 t). Moreover, the RAC foundation structures have beneficial impacts in the Metal depletion category. For example, the impact of the RAC I C30_V1 foundation is -31,7 kg Fe eq. Most of the RAC foundation structures demonstrated the overall environmental impact lower than NA foundation structures, suggesting that RAC could be suitable replacements for standard concretes.