STRABAG UK partners with the University of East London to pioneer tunnelling solution

Strabag UK and the University of East London (UEL) have announced a major new collaboration, focused on developing and commercialising a pioneering low-carbon grout that could significantly reduce the environmental impact of tunnelling projects across the UK.

Annulus grout is widely used in tunnel construction to provide essential structural support. Injected into the void between tunnel linings and the surrounding ground, it helps prevent settlement. However, conventional cement-based grouts are carbon-intensive and rely heavily on non-renewable materials and synthetic additives. The new nature-based formulation instead partially replaces cement, superplasticisers and retarders with excavated tunnelling material, filter cake from water treatment processes and agricultural by-products.

Backed by a £216,000 Innovate UK-funded Knowledge Transfer Partnership (KTP), the 26-month project will replace traditional cement-heavy annulus grout with a sustainable alternative made from repurposed construction waste and biowaste from the sugar industry. The innovation is expected to cut embodied carbon by over 61 per cent compared with conventional formulations.

Naturally occurring sucrose compounds within the agricultural waste help regulate setting time and improve flow performance, reducing reliance on high-carbon additives while maintaining technical integrity. In doing so, the project transforms multiple waste streams into valuable construction inputs, advancing circular economy principles within major infrastructure delivery.

The partnership brings together Strabag UK’s expertise in tunnelling and large-scale infrastructure with UEL’s strengths in advanced materials engineering and applied research.

The KTP project is supervised by UEL’s Dr Arya Assadi Langroudi, associate professor in geotechnical engineering. This work has stemmed from an array of nature-based and nature-inspired methods, materials and models (3Ms) that he has been developing for re-establishing the balance between natural and engineering systems.

James Keegan

James Keegan, director of environment, sustainability and innovation at Strabag UK, said: “We all recognise the challenge of enhancing circularity, resource efficiency and the sustainability of materials used in construction.

“This partnership enables cross-industry collaboration to trial and evidence a scalable, lower-carbon alternative to conventional grout that maintains the technical performance needed for complex underground works.

“By reducing embodied carbon and vehicle movements through in situ processing of waste streams, the project strengthens our growing innovation portfolio and supports our ambition to be climate neutral by 2040.

Professor Mansour Moniri

Professor Mansour Moniri, director of research and knowledge exchange at UEL, added: “By combining Strabag UK’s leadership in tunnelling with UEL’s world-class expertise in nature-inspired solutions for the built environment, this Knowledge Transfer Partnership will accelerate the development and commercialisation of an innovative annulus grout for tunnelling.”

A dedicated KTP associate will work within Strabag UK to translate laboratory research into practical, industry-ready solutions. The KTP team is also supported by UEL’s Dr Ali Abbas, associate professor of structural engineering and academic lead; Dr Wenlin Tu, who brings expertise in geopolymers and cementitious materials; and Dr Charlotte Maughan Jones, who brings expertise in CT and X-ray imaging.