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Standards for concrete, BS 8500
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On-demand webinars
Introduction to BS 8500:2023
BS 8500-1: Concrete – Complementary British Standard to BS EN 206 is the method of specifying
concrete in the UK. This bitesize webinar introduces this standard which is important for specifiers to
understand in their use of concrete. The November 2023 update to BS 8500 increases the range of
lower carbon concretes that can be specified.
Standards for concrete
Eurocode 2
In 2004, BS 8110 was replaced by EN 1992 (Eurocode 2). The Concrete Centre provided
a range of resources for designers to help with the use of Eurocode 2.
BS 8500
The key UK standard for concrete, BS 8500, is published in two parts:
BS 8500-1:2023 Concrete – Complementary British Standard to BS EN 206 – Part 1:
Method of specifying and guidance for the specifier, and
BS 8500-2:2023 Concrete – Complementary British Standard to BS EN 206 – Part 2:
Specification for constituent materials and concrete.
This standard complements BS EN 206, Concrete – Specification, performance,
production and conformity, and provides United Kingdom national provisions where
required or permitted by BS EN 206. It also covers materials, methods of testing and
procedures that are outside the scope of BS EN 206, but within national experience.
On 30 November 2023, BS 8500-1:2023 and BS 8500-2:2023 were updated. This
change to the standard increases the range of lower carbon concretes that can be
specified.
BS 8500-1:2023
The specifier is offered five approaches to the specification of concrete, with the standard
describing the correct way of compiling specifications for designated, designed,
prescribed, standardized prescribed, and proprietary concretes.
This part of BS 8500 gives detailed guidance for the specifier, including advice on
exposure classes for durability, aggregate classes, intended working life and consistence
etc., presented as a series of tables with accompanying explanatory text.
BS 8500-2:2023
BS 8500-2:2023 is intended for use by producers of concrete.
This part of BS 8500 specifies a number of basic requirements for concrete and its
constituent materials, and gives specific requirements relating to the types of concrete
listed in BS 8500-1. It also specifies requirements relating to delivery, conformity testing,
production control and transport.
This standard gives UK national provisions where required or permitted by BS EN 206,
and also covers materials, methods of testing and procedures that are outside the scope of
BS EN 206, but within UK national experience. The requirements in this part of BS 8500
are given for defined materials with an established or accepted adequate performance in
UK conditions.
The 2023 update
BS 8500:2023 incorporates the use of multi-component cements (codified in BS EN 197-
5:2021, Cement – Portland-composite cement CEM II/C-M and Composite cement CEM
VI). This allows for a reduction in the proportion of Portland cement used for a given
volume, hence reducing the embodied carbon in the concrete produced. The cements
defined in BS EN 197-5 offer up to 65% Portland cement replacement by two, or more,
low-carbon supplementary cementitious materials (SCMs) which are called additions in
the standard.
Cement production emits carbon dioxide through the fuel to heat the raw materials, and
process emissions from calcining the calcium carbonate. The largest proportion of
embodied carbon in concrete is attributable to the cement. This new update to BS 8500
provides options to reduce the mass of Portland cement and reduce the embodied carbon
of concrete.
Since the 1980s, the UK experience of using SCMs has been combining Portland cement
(CEM I) with either fly ash or ground granulated blast furnace slag. This can be done at
the cement factory or at the batching plant**.
BS EN 197-1:2011 introduced the concept of multi-component cements, CEM II/A-M
and CEM II/B-M which allow more than one addition to be combined with CEM I. The
barrier to widespread adoption of these cements had been that replacement rates were
limited to 20% and 35% respectively. The publication of EN 197-5:2021 introduced two
new cements; CEM II/C-M and CEM VI. This allows up to 65% of the CEM I to be
substituted with two or more additions so providing multi-component equivalents to the
binary combinations that have become well established in the UK.
Studies commissioned by the Mineral Products Association found that the inclusion of
limestone fines in a CEM I and GGBS ternary system improved material efficiency,
demonstrating that the limestone fines could be used as a replacement for both the CEM I
and GGBS portions of the blend. This results in concrete with both a lower embodied
carbon and a reduced use of GGBS, whilst producing an equivalent performance.
Indicative embodied carbon (modules A1-A3) for different cements and
combinations (Table 2 from Concrete Quarterly, winter 2023)
BS 8500:2023 has also considered the durability performance of ternary combinations
consisting of a range of proportions of CEM I, GGBS and limestone fines, and CEM I,
fly ash and limestone fines. These cements, and their equivalent combinations, have been
categorized according to their relative resistance to chloride diffusion coefficient (1-4)
and sulfate resistance (A-G). This grouping, the Combined Performance Category,
simplifies the specification of the wider range of cements. This categorisation is based on
the cement groupings from Concrete Society Technical Report 61: TR61 Enhancing
reinforced concrete durability and BRE Special Digest 1, Concrete in Aggressive
Ground.
BS 8500:2015+A2:2019 uses the limiting value concept to ensure the durability of
concrete. These limiting values do however reduce the opportunities to decrease overall
cement contents. BS 8500:2023 has moved towards removing unnecessary limits.
BS 8500:2023 has removed the minimum recommended characteristic strength for the
exposure classes where there may be corrosion of reinforcement due to chlorides (XD
and XS).
The recommendations when regarding the corrosion of reinforcement due to carbonation
have gone further in BS 8500:2023, with the removal of the minimum cement content
and maximum water/cement ratio limiting values, leaving just a minimum recommended
characteristic strength.
To find out more:
• Webinar: Lower Carbon Concretes – Revision of BS 8500
• How to guidance for BS 8500:2023
** Note - Cements produced at a cement factory are denoted “CEM” whereas the
combinations of Portland cement and additions produced at the concrete plants have a
slightly different nomenclature being denoted “C”.
Further guidance
NEW: How to design concrete structures using Eurocode 2: BS 8500 for
building and civil structures
Application articles in CQ
Application: Specifying lower-carbon concrete using BS 8500
The updated standard now includes a much wider range of lower-carbon mixes, potentially reducing
the UK’s annual carbon footprint by 1 million tonnes. Gareth Wake explains how specifiers can use it.
Forthcoming events
23
MAY
Fresh Concrete 2024: Accelerating deployment of innovation for a net zero future
13:00 - 13:45
Free
18
JUN
Concrete Futures: Next Generation Concrete
18:00 - 20:30
Free
About us
The Concrete Centre provides material, design and construction guidance. Our aim is to enable all those
involved in the design, use and performance of concrete and masonry to realise the potential of these
materials.
The Concrete Centre, part of the MPA
The Mineral Products Association is the trade association for the aggregates, asphalt, cement, concrete,
dimension stone, lime, mortar and industrial sand industries.
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