With low carbon solution increasingly on the agenda for developers, PHPD speaks to Michael Roddy, Managing Director SigmaRoc’s Precast Product Group, to find out more about the company’s Greenbloc cement free building block.
Why did SigmaRoc develop a cement free building block?
Concrete is the most widely used construction material in the world. Yet, while cement is the key ingredient, its manufacturing process remains a major contributor to climate change.
The cement industry has responded to the conflicting pressures with a range of initiatives – from carbon capture through to the replacement of fossil fuels used in the manufacturing process – in order to reduce its carbon footprint. However, there is a general consensus that the most effective and efficient way to achieve a reduction in CO2 is by addressing the issue at the front-end of a build. To create a low-carbon alternative to regular concrete.
One of the major challenges in finding such a solution is to identify materials that can match the excellent loadbearing properties, and indeed versatility, of ordinary Portland cement (OPC) concrete blocks. The production of ‘novel’ cements that use new ingredients has been championed as the most viable path to achieving a low-carbon alternative, by tackling the core problem of cement while maintaining the most important properties of concrete.
This was very much the genesis of Greenbloc, which is manufactured here in the UK by CCP – part of the SigmaRoc Precast Products Group. Greenbloc uses Cemfree – a material made up of ground granulated blast-furnace slag as its key raw ingredient – alongside class 1 aggregates to provide a viable, cement-free block option for housebuilders.
What kind of carbon saving benefits are achieved by Greenbloc?
For an average three-bedroom house, the use OPC blocks can account for up to 3.7 tonnes of CO2. This is clearly unsustainable, especially given both regulatory and societal pressures are closing in. Indeed, COP26 really brought the environmental impact of cement companies into sharp focus, and consumers are increasingly asking difficult questions of companies who are perceived to be contributing to, or slow in addressing, the impact of their product or services on the climate crisis.
Referring back to the example of the three-bedroom house, thanks to the addition of Cemfree, transitioning to Greenbloc would result in a 73% reduction in embodied carbon: a saving of 2.7 tonnes of CO2 per dwelling, compared to OPC. In fact, figures from the National Energy Foundation suggest that switching to Greenbloc for a housebuilding project can offset electricity emissions on an average three-bedroom house for almost four years.
Can it be used in exactly the same way as standard blocks?
Greenbloc is manufactured and packaged in the same way as an OPC block, effectively keeping everything the same in the manufacturing process and simply ‘changing the recipe’. Manufactured to BS EN 771 – 3: (2011) and compliant with Part E of the Building Regulations for Walls and Floors, it has been created to make it as straightforward as possible to replace traditional concrete blocks in a project. As such, it is suitable for all applications, including foundations, load bearing walls, internal leaves of cavity walls and partition walls.
Greenbloc was launched around 18 months ago. How has the market reacted to this new solution?
The market reaction to Greenbloc has far surpassed expectation. Indeed, we have invested heavily in our own manufacturing facilities to keep pace with demand, while the PPG group as a whole has also acquired additional UK sites to facilitate the development and manufacture of ultra-low cement-free construction products that go beyond blocks.
Is Greenbloc available in a range of sizes?
Yes, Greenbloc is available in all sizes and formats. It was originally developed as an ultra-low carbon alternative however, due to sheer volume of demand we are now manufacturing Greenbloc across all our factories. We’ve expanded the range to provide a broad range of options to housebuilders and from later this year we expect 80% of all the blocks we manufacture to be Greenbloc.
Is the company looking to go cement-free across any other product ranges?
Greenbloc is by no means SigmaRoc’s only low-carbon focus. Indeed, from the start of this year every product currently manufactured by SigmaRoc’s Precast Product Group – which comprises of Allen Concrete Ltd, CCP Building Products Ltd and Poundfield Precast Ltd – is now available in a cement-free ultra-low carbon option. This not only covers blocks, but beams, bollards, copings, kerbs and lintels, as well as bespoke solutions.
Ultimately, the construction industry is changing and understands the need to acknowledge, address and action a tangible approach to decarbonisation. We want to give stakeholders from across the housing sector the choice to use an ultra-low carbon cement-free alternative if they wish.
