Effect of Concrete Mix Composition on Greenhouse Gas Emissions over the Full Life Cycle of a Structure

Abstract

As the need to determine and monitor carbon footprints (CFs) in the construction industry grows and given that concrete is a key construction material in this sector, the authors of the article conducted a carbon footprint analysis of 15 different concrete mixtures. The method for determining the carbon footprint of the entire life cycle of concrete was presented in detail. The authors conducted a comparative analysis of the CF for an example structure made of three significantly different concrete strength classes, in addition to determining the CF for 1 m3 of concrete mix. This analysis showed the need to consider the entire structure and the emissivity associated with the consumption of reinforcing steel when selecting the most favorable solution in terms of greenhouse gas (GHG) emissions. The study revealed that the composition of the concrete mix, primarily the type and amount of cement, has the greatest influence on the carbon footprint. Furthermore, the location and geometry of the structure, as well as the number of floors, should also be taken into account when selecting concrete. In the analyzed construction, the life-cycle phases related to the incorporation of the concrete mixture at the construction site (phases A4–A5) and those related to the demolition of the concrete at the end of its life cycle (phases C1–C4) constituted approximately 10% on average of the total value of CF emissions over the entire concrete life cycle.