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.
Performance indicator: Additional cementitious materials
The amount of additional cementitious materials as a proportion of total cementitious materials
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.
In 2015, 29% of the total cementitious materials used were additional cementitious materials. The 2020 target is 35%.
Performance indicator: Recycled/secondary aggregates
The use of recycled/secondary aggregates as a proportion of total aggregates used in concrete
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 specification of recycled and secondary aggregates is a balance of resource efficiency, transportation CO2 and the implications on mix design. 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 apporopriate.In 2015 6.4% of aggregates used in concrete were from recycled or secondary sources. In 2014 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 at www.concretecentre.com/publications
Recycled steel reinforcement
Steel reinforcement manufacturing BAR members used approximately 93% of recycled ferrous metal waste as a proportion of the raw materials consumed in their electric arc furnaces (EAF). The BAR members who are reinforcement fabricators used 95% EAF material in producing and supplying rebar for use in concrete.
These indicators are part of the Materials section of the report and 2020 Commitments. An update on our Materials 2020 Commitments.