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.
Additional cementitious materials
The amount of additional cementitious materials as a
proportion of total cementitious materials
This indicator is influenced by the types of concrete required
for the market, which influences the appropriate replacement rates
of cement. The 2020 target is 35%.
In 2014, 26.2% of the total cementitious materials used were
additional cementitious materials.
The use of recycled/secondary
aggregates as a proportion of total aggregates used
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.
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 proportion in concrete has risen slightly in recent years to
over 7% by mass. 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
91% 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