Inclusion of durability of recycled aggregate concrete in life cycle assessment (LCA)

From the life cycle perspective, service life of concrete is a crucial part to be evaluated but is normally overlooked in the environmental impact assessment. While recycled aggregate concrete is regarded as an alternative material to virgin aggregate concrete, CO2 Concrete has the enhanced mechanical and durability properties matching to those of virgin aggregate concrete beneficial from carbon conditioning treatment. To validate its potential on the environment reservation, this study attempts to conduct a comparative analysis of life cycle assessment (LCA) for virgin aggregate concrete and CO2 Concrete, with two functional units (FU) applied. When considering volume and compressive strength of concrete, CO2 Concrete is much preferred for the utilization to construction. However, involving the durability parameters in FU greatly affects the performance of CO2 Concrete. Results illustrate that the selection of FU is crucial to LCA study even though the same system boundary is applied, and the inclusion of durability parameters of concrete is essential to generate an unbiased LCA results. It is also suggested that various scenarios regarding different FU criteria are presented to make a more informed decision, since there is no standard for durability indicators of concrete to be included in the evaluation.