Factors affecting the carbon footprint of reinforced concrete structures

With the need to decarbonise global cement and concrete production, much emphasis has been placed on the use of supplementary cementitious materials, such as ground granulated blast furnace slag. However, while such blends can significantly reduce the carbon footprint of cements, other options are also available to decarbonise concrete structures. For example, changing the dimensions of structural elements or concrete strengths can affect both the volume of structural concrete and its carbon footprint. This study has examined the effects of changing concrete strength, span and binder type on the carbon footprint of a hypothetical two-storey concrete structure. Furthermore, durability requirements can impose additional demands, such as higher-grade concrete or greater cover depths, affecting the structure’s carbon footprint. Thus, these structures were designed to resist a non-aggressive (XC1) and a mildly aggressive (XS1) environment. Higher-strength concrete, despite allowing dematerialisation, increased the carbon footprint of the structures, as did longer beam spans. The use of a 50% GGBS CEM III/A-S cement offered significant carbon reduction potential, with greater carbon reduction in a mildly aggressive environment. GGBS is a limited resource, so while it can always reduce concrete’s carbon footprint, its use should be focused where it can also offer durability benefits.