Concrete has been the cornerstone of construction used for buildings and infrastructure over the years. However, the conventional concrete pouring method involves cement mixing, which significantly contributes to a substantial carbon footprint. In recent years, a groundbreaking innovation has emerged – the use of cement-free concrete pouring. This adoption signifies a major shift towards sustainable construction practices. As environmental concerns intensify and regulations become stricter, embracing cement-free concrete is not just an option; it’s a necessity for a more sustainable and environmentally conscious future in construction.
In regard to growing adaptation of cement free concrete, National Grid, in collaboration with its contractor Hochtief-Murphy Joint Venture (HMJV), has accomplished a remarkable feat by completing what is hailed as the world’s largest continuous pour of Wagners’ Earth Friendly Concrete.
This significant milestone was achieved during the £1 billion London Power Tunnels project. The venture aimed to infuse sustainability into the construction process by utilizing an innovative, carbon-saving cement alternative. In this article, we explore the details of this groundbreaking achievement and its implications for the construction industry’s future.
Cement-Free Concrete: What Is It?
Cement-free concrete, also known as alternative or eco-friendly concrete, is a construction material that minimizes or eliminates the use of traditional Portland cement, a major source of carbon emissions in the construction industry. Instead, these environmentally-conscious concretes rely on alternative binding agents or innovative formulations to achieve structural integrity. Let’s delve into the advantages of this groundbreaking approach:
- Environmental Sustainability: Cement-free concrete has the remarkable ability to significantly reduce carbon emissions. Traditional concrete production is responsible for a substantial portion of global CO2 emissions. By utilizing alternative binding agents like fly ash or slag, cement-free concrete can slash carbon emissions by up to 80%.
- Energy Efficiency: Traditional cement production is energy-intensive. In contrast, cement-free concrete requires less energy to produce, contributing to lower overall energy consumption in construction.
- Durability and Longevity: Cement-free concrete often exhibits superior resistance to chemicals, corrosion, and environmental factors, resulting in increased durability and the extended lifespan of structures.
- Reduced Waste: Traditional concrete production generates a substantial amount of waste. In contrast, cement-free concrete production typically results in less waste due to optimized material usage.
- Versatility: Cement-free concrete can be formulated to meet various performance requirements, making it suitable for a wide range of construction applications, from residential buildings to infrastructure projects.
- Regulatory Compliance: As environmental regulations become more stringent, the adoption of cement-free concrete can help construction projects meet compliance standards and avoid penalties.
The development of cement-free concrete continues to evolve, with ongoing research focused on enhancing its properties and performance, ensuring a bright future for sustainable construction.
About the Cement Free Concrete Used For The Project
The cement-free concrete used for this project, developed by Wagners and supplied by Capital Concrete, incorporates a binder composed of ground granulated blast furnace slag and fly ash geopolymer concrete. This concrete is chemically activated using industrial waste products instead of traditional cement. The result is a concrete that reduces carbon emissions by approximately 64%, translating to an estimated saving of 111 kilograms of CO2 per cubic metre compared to traditional concrete. Together with contractor HMJV, National Grid conducted extensive testing of Earth Friendly Concrete (EFC).
The Herculean Pour: A World Record
Capital Concrete, the project’s supplier, delivered an astonishing 736 cubic meters (equivalent to 736,000 liters) of cement-free concrete to form the base of a 55-meter deep tunnel drive shaft at National Grid’s Hurst substation in south London. The most remarkable aspect of this achievement was the single continuous pour, spanning an astonishing 11 hours. Previously, the record for an EFC pour was held at High Speed 2’s Euston station site, where John F Hunt used cement-free concrete to create a temporary foundation slab.
Youthful Ingenuity Leading the Way
National Grid attributes the adoption of Earth Friendly Concrete to a team of young engineers who championed the cause on the project. Their enthusiasm and vision were further supported by HMJV’s consultants at Aecom, Mott MacDonald, and WSP. These teams conducted extensive trials at various London Power Tunnels sites to ensure the feasibility and effectiveness of this eco-friendly solution.
The Purpose of the Pour
At the Hurst substation site, the monumental pour was necessitated to fill the base of the 55-meter deep tunnel shaft to its permanent level. This followed the completion of 9.2 kilometers of tunnelling across two tunnel drives, spanning from Hurst to Eltham and Crayford.
A Vision for a Sustainable Future
National Grid’s project director, Onur Aydemir, expressed excitement about the project’s sustainability measures, stating, “We are always looking for new ways to innovate, and to now be using this carbon-saving cement-free alternative to conventional concrete at scale and on-site is exciting.” Furthermore, Aydemir mentioned that this world record-breaking pour provides a unique opportunity to evaluate the technology for future potential rollout across their network in England and Wales, aligning with their ambition to achieve net-zero construction on all projects by 2025/26.
Hochtief-Murphy Joint Venture technical lead Raj Kundan emphasized the collaborative effort involved in this achievement, showcasing the industry’s commitment to innovation and reducing carbon emissions. The successful completion of the largest continuous cement-free concrete pour serves as a testament to the ingenuity and teamwork of all parties involved.
Global Partnership for Sustainable Solutions
Wagners, an Australian company, has a license agreement in the UK with London-based Capital Concrete, co-owned by Brett and Breedon, to supply off-the-shelf chemicals for mixing Earth Friendly Concrete on-site. Andy Izod, UK regional manager for Wagners, expressed hope that other major clients would follow National Grid’s lead in decarbonizing the construction sector.
Capital Concrete’s managing director, Luke Smith, highlighted their commitment to delivering sustainable alternatives. He stated, “We have been supplying Earth Friendly Concrete since January 2020 as a low carbon, high-performance alternative to standard cement-based concrete.” Smith expressed delight in Capital Concrete’s contribution to this monumental achievement, underscoring their technical expertise and customer-centric approach that made this feat possible during the London Power Tunnels project.
Additional Sustainability Measures for the London Power Tunnels Project
In addition to the groundbreaking use of cement-free Earth Friendly Concrete, the London Power Tunnels project has implemented several other environmentally friendly measures to minimise its construction’s impact on the environment. These measures include:
- Designs and Construction Methodologies: The project has focused on optimizing the designs and construction methods for the tunnel and shafts network. This optimization effort, led by HMJV, has resulted in significant CO2 savings of approximately 50,000 tons. This achievement represents a remarkable 30% reduction compared to the baseline.
- Waste Management: An impressive 99.98% of the project’s waste has been diverted away from landfills. This marks a substantial 21% reduction in carbon emissions compared to the pre-project baseline for shafts, tunnels, and headhouses. This reduction is equivalent to avoiding the release of 25,250 tons of CO2.
- Innovative Substation Technology: At the core of the project, in Bengeworth Road, Lambeth, a new 400kV substation is being constructed. What sets this substation apart is its use of SF6-free gas insulated switchgear technology. This innovative approach represents a significant milestone in the U.K. as it is the first of its kind.
“At HMJV, in conjunction with our supply chain family, we strive to advance innovative and cutting-edge solutions – and the incredible work the team have done on the project in the trialling and large-scale use of Earth Friendly Concrete in temporary as well as permanent applications is a great example of that,” said Raj Kundan, HMJV Technical Lead.
The success of the London Power Tunnels project serves as a testament to the industry’s dedication to reducing carbon emissions and building a sustainable future. As we strive to build a greener, more sustainable world, the adoption of cement-free concrete serves as a shining example of what can be accomplished through determination and the pursuit of eco-friendly solutions.
References; theconstructionindex.co.uk, geplus.co.uk tunnelsonline.info, nationalgrid.com, the brett.co.uk