PUDLO Waterproof Systems & Cemfree Zero-Cement Concrete, part of the DB Group Ltd

The £1.5bn A14 Cambridge to Huntingdon improvement scheme ran from Nov 2016 until May 2020. Materials Engineer for the A14 Delivery Integrated Delivery Team, Highways England, Donald McDougall, was approached by Mick George and DB Group (manufacturer of Cemfree) to explore the viability of using this innovative low-carbon cementitious material for various applications on this major roadway project.

The Gascoigne Estate in Barking was first built in the 1960s and has become the subject of a massive redevelopment scheme to bring it into the 21st century. In the spirit of sustainable construction, Bouygues UK seized the opportunity to investigate the huge sustainability potential of Cemfree with some in-situ trials, conscious of the significant carbon saving that is achievable with this zero-cement concrete. Jean-Marie Perret, Bouygues UK Project Manager, decided to carry out a full scale on-site evaluation of Cemfree concrete to gain first-hand experience of this revolutionary new material and compare its properties to traditional concrete.

In 2013, when Cemfree was still in its infancy, DBG decided to pour the first ever in-situ Cemfree slab. Although the slab was large, measuring 930m2, the real challenge lay in pouring the Cemfree mix in temperatures of -2°C; far from ideal conditions for placing concrete. As well as contending with below-freezing conditions, DBG wanted to lay the slab in one continuous pour with no joints, a practice that would not normally be recommended for traditional concrete slabs of this size, due to the increased risk of cracking.

This coastal project in Essex showcases the commercial use of Cemfree in a UK tidal sea defence application. It was a detailed scheme that required bespoke formwork to prevent the washout of material as well as the input of the Cemfree team to ensure the pours went to plan. The Environment Agency exists to protect and improve the environment, and while development is not always desired, it’s often essential, and the Agency strives to carry it out in the most sustainable way possible. Environmental Manager, Steve Livingstone, spearheaded the choice for Cemfree for this sea defence system based on its significant carbon saving potential.

In early 2017, Cemfree ultra-low carbon concrete, part of David Ball Group Ltd, began a journey with Oxford-based sustainable house builder, Greencore Construction Ltd. Greencore’s ethos was founded on its ambition towards ‘building a low carbon future’, with owner Ian Pritchett and project manager Piers Ashley-Carter ensuring the work they do today consistently embodies this aspiration. Sustainable construction is at the heart of what Greencore does, but delivering a truly sustainable home always presented one obstacle – the concrete in the foundations and slabs that these bespoke properties were being constructed on – as they remained the only elements of the construction heavily saturated with embodied carbon.

Cadent Gas require to divert the existing high pressure gas pipeline at Austrey to Shrewley to provide mitigation from external loading from future HS2 traffic. As well as standard trench construction the diversion also compromises tunnelling at certain locations along the route.To launch and receive the tunnel boring machine (TBM) a secant piled shaft is constructed at the launch and reception sites.Secant piled shafts are constructed with bored piles and typically compromise overlapping primary/soft and secondary/hard piles. Primary/soft piles are formed without reinforcement from a weak bentonite slurry to low strength concrete typically C8/10 with secondary/hard piles installed with reinforcement and using structural concrete typically at C30/37 or higher and cutting into the primary/soft piles to form an overlap which prevents water and fines entering an excavation. Secant pile shaft structures for TBM works are typically temporary works designs with less onerous full design life/durability criteria. The selection of the soft/primary pile concrete mix is critical to achieve the correct balance of structural performance and durability where required without impeding the installation of the secondary/hard piles. As very stringent installation tolerances are needed the strength gain profile of the primary/soft pile concrete mix is also required to be clearly understood to calculate the timings of the secondary/hard pile installation.It is a priority for us to find the latest technology to minimise our impact on the environment. As a result, we were keen to approach DB Group to consider how we could use cement-free concrete on one of our projects. This is where Cemfree comes in. It is an ultra-low carbon alternative to standard concrete whereby OPC is replaced with novel alkali activated cementitious material (AACM). As it does not contain any OPC, it can save up to 88% of CO2 emissions on a project.Cemfree has been used in the UK since 2010. However, so far it has only been used on small scale projects. Therefore, we have partnered with DB Group, Hanson and BRE to trial Cemfree concrete on the primary/soft piles for the secant shaft piling at our HP11 gas main diversion project and better understand and develop its characteristics for future use in piled structures.

This new Berkeley Homes development is situated near the banks of the River Thames in the Royal Borough of Greenwich, offering fantastic riverside living. Berkeley Homes has a strong sustainability agenda, continuously seeking to make use of new sustainable products on site. For this project Cemfree was chosen to make up the capping beams that form the Thames flood defensive system which sits on the south side of the river, next to the Woolwich ferry.

Environmental considerations and design were core threads running through the project which contributed to the client obtaining planning permission in a location of high landscape quality. The client had wished to build a house with a low carbon footprint in materials of construction, as well as being highly insulated, and using air source heat to give a low carbon footprint in use. A low-carbon alternative to concrete was considered from the outset. As such, Cemfree was the only suitable material which has support from manufacturer-supplied test certificates to gain approval by Building Control for this application.

Tideway Central is part of Thames Tideway Tunnel, which is a new enhanced sewer system currently being built in London that will help protect the River Thames by tackling the problem of overflows from the capital’s Victorian sewer. Kirtling Street is Tideway Central’s biggest site, bringing London’s sewer system into the 21st century as well as creating thousands of jobs and helping to boost the economy.FLo Environmental Manager, Camila Bernal and FLo Section Engineer, Claire Kilrane expressed a desire to utilise Cemfree in an on-site trial, after learning about the potential carbon savings that could be made with this innovative product. It was decided that two hoarding post bases would be the ideal application for Cemfree to observe what it is like to mix, place and cure and how it performs in comparison to traditional concrete.

Murphy Ground Engineering installed 750mmand 880mm cased rotary piles up to 34.0m toform a triple storey basement secant wall andbearing piles for a new Hotel development inWestminster. As part of the top downconstruction methodology and due to limitedperipheral space, a temporary slab wasdesigned to accommodate construction plantduring the bulk dig and spoil removal.Due to the loadings on the temporary slab the design required 6# 880mm piles to 25.0m depth to provide support to the slab. As these piles are temporary works in design the use of Cemfree concrete was proposed, although with specific structural requirements it was imperative for the Cemfree concrete to achieve 40N strength at 56 days as well as perform to the required piling concrete characteristics as would be expected. A total of 95m3 of “C32/40” Cemfree concrete was supplied over a period of 4 days to construct the temporary works piles using temp cased rotary bored methodology.The use of Cemfree at Newman St was aligned with MGE involvement in the LOCOWAG project led by DB Group (Holdings) Limited (DBG). The project is government funded via the Innovate UK scheme and runs from November 2020 to November 2022.