Low carbon concrete turns Hexham flood defences green

In a UK first, the Environment Agency, BAM, Arup and Tarmac have successfully trialled the use of two low carbon concrete mixes for works at the Hexham Flood Alleviation Scheme.

The low-carbon concrete has been used across 3 panels, totalling 27 metres of the £6.5 million Hexham flood defences, as part of a plan to reduce the carbon footprint of the construction of flood defences, without compromising the strength and resilience of these structures.

The trials involved the first use in permanent works of a new Portland Limestone Ternary mix developed by Tarmac which has delivered carbon savings of 64% compared to traditional cement-based concrete.

Also tested was an Alkali Activated Cementitious Material (AACM) which reduced carbon emissions by 70%, per cubic metre of concrete, across the section of the wall where low carbon concrete was used.

Traditional concrete production contributes around 7% of global carbon emissions and concrete is one of the most-used resources worldwide. Its carbon footprint is due to a combination of the chemical reactions and the energy-intensive methods that go into the production of cement, the key binding element in concrete.

Advances in the UK concrete industry mean that concrete currently accounts for around 1.5% of UK carbon emissions.

The trials have been delivered by the Environment Agency’s Collaborative Delivery Framework Hub A, a collaboration between the Environment Agency, Arup and BAM, to deliver flood defence schemes across North East England.