Additional cementitious materials
There are significant volumes of by-product materials such as ground granulated blastfurnace slag (GGBS) and fly ash that can act as part of the cementitious binder in concrete. These materials have a lower embodied carbon than cement and can also influence the appearance and performance of concrete. This indicator, which is strongly influenced by the types of concrete required by the construction sector, reports the proportion of additional cementitious material as a percentage of the total cementitious material.
Performance indicator: The amount of additional cementitious materials as a proportion of total cementitious materials
In 2018, 26.2% of the total cementitious materials used were additional cementitious materials. The 2020 target is 35%.
Depending on the application and the type of concrete there is often an opportunity to incorporate recycled aggregates previously used in other projects and secondary aggregates that may be by-products from other industrial processes. The inclusion of recycled and secondary aggregates in concrete is a balance of resource efficiency, transportation CO2 and the implications on mix design and concrete performance. Consequently, these aggregates should be used in concrete production where it is technically and environmentally beneficial to do so. The industry continues to operate on this principle and uses recycled materials where possible and appropriate.
Performance indicator: The use of recycled/secondary aggregates as a proportion of total aggregates used in concrete
In 2018, 5.7% of aggregates used in concrete were from recycled or secondary sources. In 2018 around 28% of all aggregates in GB were recycled or secondary, far above levels elsewhere in Europe.
Recycled concrete, as well as being used as an aggregate, is often used at the source of demolition, as part of sub-structures and external landscaping for a new development. For more information download Specifying Sustainable Concrete and Concrete and BREEAM from The Concrete Centre.
Recycled steel reinforcement
Steel reinforcement manufacturing BAR members used approximately 96% of recycled ferrous metal waste as a proportion of the raw materials consumed in their electric arc furnaces (EAF) in 2018. The BAR members who are reinforcement fabricators used more than 95% EAF material in producing and supplying rebar for use in concrete.