There may be a way to go, but cement substitutes are taking polished concrete one step closer to sustainability
Contractor Lazenby is working to make polished concrete greener.
Over the past four years the firm has been moving away from cement-based products, opting to use cement substitutes instead.
Cement, the key ingredient in concrete, is responsible for around 8 per cent of the world’s CO2 emissions thanks to a complex manufacturing process that produces four billion tons of product a year.
'Making sustainable choices means that most of our products are compatible with up to 50 per cent cement replacements,' explains managing director Ed Lazenby.
Finding a substitute for traditional cement
The most common cement alternative is ground granulated blast furnace slag (GGBS), which is produced as a by-product of the iron-making industry.
Benefits of GGBS include lower emissions, reduced landfill and minimal mineral extraction. Most importantly, it meets all the criteria for sustainable construction.
'Many projects that we have worked on have achieved the best possible BREEAM rating,' says Lazenby. 'We want to install quality concrete products to the highest standards while ensuring our materials and supply chain have a less detrimental impact on the environment.'
Lazenby’s chosen GGBS is Regen, a leading brand manufactured by Hanson Cement in the UK. 'All our products are sourced as locally to the project as possible. By working with a UK-based company we can reduce the mileage of our raw materials.'
The advantages of cement alternatives
Evidence suggests that sustainable cement substitutes offer a significant eco-advantage over traditional products, with the potential to lower CO2 emissions by as much as 90 per cent.
'Replacing 70 per cent of cement with Regen in one ton of cementitious material can reduce CO2 by up to 600kg per ton,' explains James Branch, technical services manager at Hanson Cement. 'This is obviously a significant reduction in emissions, which can have a huge impact on a project’s overall sustainability.'
There are also practical benefits. Regen handles aggressive environments much better than traditional cement and there is a lower risk of thermal cracking, making it ideal for larger pours.
There are aesthetic advantages too. Cement alternatives are versatile in appearance, which means they work well with Lazenby's wide range of pre-set and bespoke colours.
With a number of sustainable cement alternatives available to contractors, choosing the right one is key to a seamless transition. 'Research and development was essential to minimise the impact of incorporating cement alternatives into our products,' says Lazenby.
'Some cement replacements can affect concrete’s setting time. While this can be useful depending on the project, finding alternatives that don’t prolong the installation process is essential. It’s all about finding the balance between on-site requirements and lower carbon concrete.'
The future is cement-free
Many architects are committed to substituting traditional cement in its entirety by 2040.
'While Lazenby has made great strides in minimising its carbon footprint, our ambitions are to increase the use of cement substitutes and we’re working towards a completely cement-free Terrazzo system.'
As an end-product, polished concrete is thermally efficient, low maintenance and long-lasting. It’s even recyclable.
Cement manufacturing produces more emissions than any other part of the polished concrete manufacture and installation process. By making greener choices here, contractors can substantially boost polished concrete’s green credentials.
For more information and technical support, visit lazenby.co.uk