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Decarbonising building materials is key to creating the low and zero carbon infrastructure of the future and contractors can play an important role by choosing to use lower carbon products.
Concrete is a good starting point as it is the most widely used building material in the world, but its production is energy and carbon intensive due to the presence of Portland cement (PC) as a key ingredient.
Heidelberg Materials UK has invested heavily to reduce process emissions and has increased alternative fuels usage to 80 per cent. However, almost 70 per cent of the CO₂ emissions produced arise from the chemical reactions that take place during manufacture, so cannot be avoided by using low carbon or renewable energy sources.
Carbon captured net zero cement
That is why the company is also leading the way in developing carbon capture and storage (CCS) facilities which prevent these emissions from entering the atmosphere, and allow it to produce evoZero, the world’s first carbon captured net zero cement.
evoZero is already available in the UK from the company’s Brevik cement works in Norway, where Heidelberg Materials has built the industry’s first large-scale CCS facility, and could also be produced at its Padeswood cement works in north Wales as soon as 2029.
However, until this CCS technology is widely available, specifying the use of supplementary cementitious materials (SCMs) – which reduce the CO₂ impact of concrete by replacing some of the cement content – remains vital to delivering low carbon concrete.
Most effective SCM
The best known and most effective SCM is ground granulated blastfurnace slag (GGBS), a byproduct of iron and steel making, which has been used as a SCM for over a century. It can be used almost anywhere concrete is needed and can replace a substantial part of the PC content – up to around 70 per cent, and even higher in special applications.
This high replacement level means GGBS is the most effective SCM in terms of delivering carbon reduction as others can only be used at lower replacement levels without impacting the performance of the concrete.
Clarity on the environmental performance of Heidelberg Materials UK’s evoBuild low carbon GGBS is provided in an Environmental Product Declaration (EPD). The product is readily available in the UK and the company has a safe and secure supply for its anticipated demand. evoBuild low carbon GGBS is also proven to provide enhanced concrete performance through improved durability.
Additional SCMs
Heidelberg Materials offers other SCMs, including natural pozzolans and limestone powder, and has successfully supplied calcined clay from its Greenwich concrete plant in London.
“We carried out trials replacing up to 50 per cent of the cement content with calcined clay,” explains Nina Cardinal, Technical Strategy Director at Heidelberg Materials UK.
“The results were extremely encouraging. In addition to the carbon reduction benefits, the trial demonstrated that the strength performance of the concrete produced using calcined clay can match GGBS at replacement levels of up to 30 per cent.
“We have now successfully supplied a low carbon concrete mix containing calcined clay to a live construction site, allowing our customers to gain experience with a new SCM.”
Specification made easy
The company has also made it easy for specifiers to specify products that target carbon reduction with its evoBuild low carbon concrete.
All of the products in the range offer high quality and reliability with the benefit of significantly reducing CO₂ emissions. They meet strict sustainability criteria giving contractors the confidence to make informed decisions.
Heidelberg Materials also has a team of experts available to guide customers through its evolving range of lower carbon options.
Talk to Heidelberg Materials’ technical team at: concrete.technical@heidelbergmaterials.com