Durability related functional units for life cycle assessment of high-volume fly ash concrete

High-volume fly ash (HVFA concrete) concrete has been developed in order to reduce the environmental impact of cement production. By replacing at least 50 % of ordinary portland cement with pozzolanic fly ash, an important reduction in greenhouse gas emissions can be achieved. However, this proposition is only valid if HVFA concrete is as durable as portland cement concrete. In order to deal with differences in durability, the amount of concrete needed in a 1 m3 structure with a service life of 50 years is choosen as functional unit for life cycle assessment (LCA). This way, additonal emissions caused by structure replacement over time are included. Accelerated test procedures for carbonation as well as freezing and thawing with deicing salts were used. Base on long-term damage prediction, a significant reduction in environmental impact is observed for concrete mixtures with 50 % fly ash when subject to carbonation. However, freezing/thawing resistance is poor.