Cemfree ultra-low-carbon cement used on M25

Environmentally friendly concrete used volumetrically for first time on Woodford West Viaduct

WORKING on behalf of Connect Plus, a team from Jackson Civil Engineering, DB Group and Axtell have achieved a 77% reduction in CO2 by using volumetric mixer trucks to pour ultra-low-carbon Cemfree concrete on the Woodford West Viaduct.

This is the first time Cemfree has been used volumetrically, and the potential for reducing carbon emissions on future highways projects is said to be extensive.

Cemfree was successfully piloted at the Woodford West Viaduct where it was to pour a concrete hardstanding beneath the structure. This initial application amounted to 52 cubic metres of concrete, leading to a saving of 9.4 tonnes of CO2 compared with using a conventional mix, thereby greatly reducing the environmental impact.

Jackson have been working with low-carbon concrete for the past few years but say the material has always been challenging to use on the M25, due to the availability of batching plants, which usually shut at night.

Instead, this trial has proven the suitability of volumetric mixer trucks, which are able to produce just the right amount and, crucially, at the right time, day or night, without having to rely on a batching plant to dedicate an entire silo to the product.

Tony Sheridan, DB Group’s commercial manager, said: ‘As well as enabling significant carbon savings versus a more traditional concrete mix, Cemfree offers enhanced durability and considerable savings in water consumption.

‘Cemfree also allows contractors to consider larger pours with fewer joints, as the relatively low heat generated during the curing process leads to less cracking in the finished concrete.’

He added: ‘Interest in Cemfree has grown considerably over the past few years as environmental issues and climate change have come more into public focus.’

Paul Watson, director of Jackson’s Highways Division, said: ‘We’re really pleased to have introduced ultra-low-carbon concrete to the M25, and credit must go to Connect Plus, who, as an intelligent client, supports us in trialling new materials.’

‘Our work with Axtell has proven that we’re able to supply the low-carbon material at no extra cost, and without having to place a large order with a ready-mixed concrete supplier, which makes the material far more accessible to use on the M25.

‘We hope this marks a turning point on the M25 and the wider highways sector, for using low-carbon alternatives.’

Conventional concrete using ordinary Portland cement (OPC) causes almost a tonne of CO2 per tonne of material produced and contributes 8–10% of global greenhouse gas emissions, twice as much as aviation.

Cemfree removes the need for OPC, using 95% ground granulated blast-furnace slag (ggbs) and a 5% alkali activator instead. The CO2 value of Cemfree is 114kg/tonne, 77% lower than conventional mixes.

Andy Dean, chief executive officer of Connect Plus, said: ‘Connect Plus are committed to reducing carbon emissions across the M25 network and we’re thrilled to be supporting this progressive innovation.’

Andrew Axtell, proprietor of Axtell, added: ‘We’re keen to offer this low-carbon cement alternative as part of our various offerings as we know that this is definitely the future.’