Low carbon concrete trials

Building company Skanska and the National Composites Centre (NCC) are trialling the use of low carbon concrete and basalt fiber reinforcement to build roads.

This is part of a £282m project funded by National Highways (NH), which compares the efficiency of the low carbon concrete with traditional steel reinforced concrete.

“Basalt is a lightweight composite material consuming 62% less CO2e than steel during its manufacture,” said Malcolm Newton, director at Basalt Technologies. “It comprises a non-metallic inert material that does not corrode, making it more durable than steel. Basalt fiber reinforcement is also four to five times lighter than steel, making it safer to handle, fix and transport with fewer lorry movements.”

The production of cement, a key ingredient in concrete, currently accounts for around 7% of the world’s CO2 emissions, although in the UK, this figure is less than 1.5% due to the use of low-carbon cement substitutes. 

Two types of concrete were provided for the trial: a mix comprising conventional blended cementitious material and a low carbon alternative mix incorporating an alkali activated cementitious material (AACM) in place of the cement.

According to the Robert Gossling, head of commercial engineering for Tarmac, which provided the materials, the new product can deliver a carbon footprint up to 80% lower than a standard CEM I concrete.

“This project, its learnings and test results, is critical to understanding the impact of low carbon concrete and advanced composite reinforcement systems to reduce embodied carbon for the construction sector,” said Carys Holloway, technology programme manager, NCC. “I am eager to witness the expected ease of planing out of the basalt fiber reinforced slabs for recycling and the potential that has for end-of-life scenarios.”