Resource Efficiency

Performance indicator

The concrete industry, as well as recycling its own process waste, is very active in the use of by-products, secondary materials and material diverted from the waste stream to reduce its demands on primary raw materials.

Additional cementitious materials

The amount of additional cementitious materials as a proportion of total cementitious materials


Additional cementitious materials


Concrete manufacture uses by-products that are cementitious and originate from other industries such as fly ash from power stations and ground granulated blastfurnace slag (GGBS) from the iron and steel industry. These materials have a lower embodied carbon than the cement they replace and can also influence the appearance and performance of concrete.


The indicator reports the percentage of additional cementitious material as a percentage of the total cementitious materials. In 2013 this was 28.5%. The target for 2020 is 35%. This indicator has been rebased following a review of the materials classified as ‘additional cementitious’.

Recycled/secondary aggregates

The use of recycled/secondary aggregates as a proportion of total aggregates used


Recycled/secondary aggregates


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 processes e.g. ‘stent’ from china clay production and granulated slag from steel making.

Environmentally it is preferable to use these materials as close as possible to their origin, although their embodied CO2 value can exceed virgin materials. This decision should be made on a project basis to ascertain benefit. For this reason the concrete strategy does not include a numerical target for the proportion of recycled/secondary aggregates of the total aggregates used but reports on the trend. This has been consistent at around 5% by mass in concrete production, although some products can have significantly higher levels.


Specification of recycled/secondary aggregates is incentivised in schemes such as BREEAM. Guidance on the 2014 update to BREEAM is available from The Concrete Centre at

Recycled steel reinforcement

Steel reinforcement manufacturing BAR members used around 94% of recycled ferrous metal waste as a proportion of the raw materials consumed in their electric arc furnaces (EAF). While reinforcement fabricators used 100% 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.