Case Studies in Construction Materials (Dec 2024)
A critical review of embodied carbon classification schemes for concrete
Abstract
Concrete and cement production account for approximately 9–10 % of global carbon dioxide emissions. Schemes are under development to establish shared definitions and rules for classifying and communicating the cradle-to-gate embodied carbon (EC) of concrete, which can be used as a basis for policies to decarbonise these industries. This paper critically reviews eight recently developed EC classification schemes for concrete, examining their specifics, limitations, and the potential for convergence upon a single, globally-applicable scheme. Important differences exist between them, regarding a) whether rating bands should remain static or be periodically updated to reflect the EC of concrete currently available in the market and b) whether baseline EC values should be established for each strength class, and/or based on other factors like design application, region, or production route (ready-mix versus precast). A recently proposed classification scheme for the UK addresses both issues by combining static rating bands applicable to all normal-weight concrete, with up-to-date industry data, thus communicating the EC of commercially available concrete. Industry EC data can then be segmented for variations in concrete production and use, enabling better like-with-like comparisons between concrete products considered for projects. Convergence upon a single, globally applicable classification scheme is proposed as it would facilitate easier comparisons between concrete products across different regions. This paper argues that achieving this goal is feasible provided the scheme establishes a shared LCA methodology, and variations of the scheme are developed to accommodate differences in concrete strength and carbon intensity measurement units typically used in different regions.
