The UK Government has a target to be ‘net zero’ of all greenhouse gas emissions by 2050, with the construction industry targeting a 78% reduction of emissions by 2035. Concrete contributes towards 8% of global CO2 emissions due to the carbon intensive production of cement. To help towards achieving a ‘net zero’ target, VINCI Construction, in partnership with Ecocem, has developed and produced a cement alternative for use in concrete. This new concrete product contains 0% Ordinary Portland Cement (OPC) and is classified as an Ultra Low Carbon Concrete (ULCC). The cement replacement consists of 96% Ground Granulated Blastfurnace Slag (GGBS) a by product of the steel industry and contributing to a circular economy, and 4% alkali activated binder.
Following extensive research, development and mix testing of the ULCC by VINCI Construction, a trial pour of 150m3 was undertaken in November 2021 at Taylor Woodrow’s (the Civil Engineering division of VINCI Construction UK) Eco Park South Project, in Edmonton, North London. The structure was a 500mm thick ground slab for a waste recovery facility building.
Following great success of the first pour, a total of 350m3 of C40/50 compressive strength concrete have been poured using this product on the project to date.
Performance of the concrete (workability and strength) has exceeded expectations. This has been the first time this ULCC product has been placed via a pump in the world; developing a pump mix design is critical to overcoming the barriers of largescale concrete pours. The ULCC also requires a minimum temperature of 15 degrees Celsius when placing it, which would ordinarily hinder its use within the UK industry; however, the project has achieved multiple pours throughout the winter months. 93% of the design strength of the concrete was achieved within 28 days which greatly exceeded all initial
expectations. (As the mix was based on achieving strength at 56 days).
Taylor Woodrow believes that this ULCC product is an innovative solution that will help the construction industry support the UK Government’s ‘net zero’ target and to reduce their contribution to the global warming crisis. If promoted correctly and supported by industry bodies, ULCC will be a product that is specified as standard for future building projects. Taylor Woodrow has begun with producing a case study on the Eco Park South project, produced an e-learning module for their employees and promoted the success of the concrete pours throughout the industry via press releases and social media.
Key achievements:
- A total of 350m3 of Ultra Low Carbon Concrete was poured, resulting in a saving of up to 70% CO2 compared to traditional concrete.
- Taylor Woodrow’s Eco Park South Project are the first in the UK to use this sustainable Ecocem Ultra Low Carbon Concrete, containing zero traditional Ordinary Portland Cement, and the first project worldwide to develop a pumpable mix for use with a concrete pump.
- The Ultra Low Carbon Concrete is a new and innovative sustainable product at the forefront of technology and is consequently not covered by British Standards. There were many challenges that were overcome to enable the use of this concrete and a case study has been developed to share the lessons learnt and promote the use of carbon reduction through the utilisation of Ultra Low Carbon Concrete throughout the industry.
