Revised version of BS 8500
5 Dec 2023
On 30 November 2023, BS 8500-1:2023 and BS 8500-2:2023 were published. This change to the standard increases the range of lower carbon concretes that can be specified.
Since the 1980s, the UK experience of using supplementary cementitious materials (SCMs) has been combining Portland cement (CEM I) with either fly ash or ground granulated blast furnace slag. In 2021, the cement standard EN 197-5, was published and allowed cements with up to 65 per cent of the Portland cement clinker to be substituted with two or more SCMs, so providing multi-component equivalents to the binary combinations that have become well established in the UK. Extensive testing was carried out on these new multi-component cements, which has led to the update in BS 8500:2023 that will enable the specification of these lower carbon concretes.
With the new standards now available, the CEM I content in concrete can be replaced with up to 20 per cent of limestone powder, an SCM that can be sourced locally across the UK. For every 5 per cent of limestone powder used, a 5 per cent CO2 reduction can be delivered per tonne of concrete.
With the potential to use these new concretes across all mainstream applications, the associated carbon saving could add up to an annual saving of 1 million tonnes of carbon dioxide.
Research 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.
More information on BS 8500:2023.