Proving low-carbon concrete performance with AI maturity sensors

First published in the December 2025 issue of Quarry Management as Concrete Evidence

By Joe Kirwin, commercial manager London & South East Readymix, Tarmac

As the UK Government looks to accelerate house building and major infrastructure delivery while simultaneously targeting net-zero emissions by 2050, contractors face conflicting priorities.

With the Labour Government focused on getting Britain building faster, there is an increasing pressure from developers for contractors to deliver projects on time and to budget. These timescale restraints can lead contractors to believe there is insufficient time for the technical innovation required to deliver carbon savings, which can be a complex and time-consuming process.

Yet, there is a pressing need for action within the construction sector if the UK is to achieve its wider net-zero goal. Embodied carbon emissions from the production and usage of construction materials account for around one-tenth of the UK’s total greenhouse gas emissions, according to 2024 data from The UK Green Building Council. A growing number of local authorities are implementing embodied-carbon assessments, making optimizing material choices an essential consideration.

When it comes to concrete, there are multiple measures that can reduce the carbon footprint of building products, such as sourcing aggregates from local quarries, investing in sustainable logistics, and substituting the clinker in cement with lower-carbon alternatives.

Recent updates to the BS 8500 standard for concrete allowing for up to 20% of CEM I content to be replaced with limestone fines have unlocked a wider range of lower-carbon concrete solutions, with approximate CO2 reductions of 5% per tonne of cement for every 5% of limestone powder used.

However, extensive testing is still required at a project level to ensure that these lower-carbon concrete mixes deliver the required strength and performance in varying weather conditions. For large-scale projects, the heat generation from the significant volume of materials required can also impact strength development, making thorough testing an important step of the specification process.

This typically takes place by measuring the compressive strength of concrete cubes, a time-consuming procedure that requires extensive collaboration between subcontractors and testing facilities and can result in long gaps between concrete pours.

To tackle this issue, Tarmac have developed CEVO Digital concrete maturity performance sensors, which provide real-time data on the concrete’s strength and temperature, enabling contractors to strike formwork up to 40% faster.

But this technology goes beyond traditional maturity sensors, allowing contractors to make sustainable materials choices while ensuring maximum efficiency that supports them in keeping to the programme agreed with developers.

Powered by Converge Concrete DNA software, the technology combines historical Tarmac data on the performance of low-carbon concrete mixes with predictive AI to identify, optimize, and engineer out concrete overstrength and deliver carbon savings. The combination of Tarmac’s technical expertise with Converge’s AI technology helps to drive data-informed decision making, increasing confidence in the performance of lower-carbon concrete solutions and encouraging contractors to make the switch.

These data can then be accessed on site in real time using the Converge smartphone app or computer platform, as well as being stored for quality assurance purposes.

AI sensors in action

CEVO Digital was initially conceived as a ‘plug-and-play’ maturity-monitoring system to save contractors time and improve testing efficiency, with a 12-month pilot scheme in which Tarmac trialled the software and assessed its commercial possibilities. Since the expansion of CEVO’s capabilities to help with specifying more sustainable concrete mixes, the technology has already significantly enhanced carbon savings on a number of large-scale construction projects.

For example, the sensors were used by a subcontractor working on a major life sciences development project to reduce the embodied carbon emissions of the concrete mix, in line with the key aims of the principal contractor.

Timeliness was also an important consideration, since the need for a water company to divert a sewer under one of the buildings being constructed meant the contractor was working to a tight pre-agreed schedule for the volume of concrete that could be poured each day.

Tarmac provided pre-calibrated mix designs for the project’s reinforced concrete frames, with the CEVO Digital mix AI software allowing the site team to make data-led decisions in response to changing environmental conditions. The team of experts were then able to quickly and efficiently select the most suitable mix with the lowest-possible carbon value without impacting programme strength or quality.

Employing 53 sensors and supplying 4,500m3 of concrete over 28 pours, the project achieved a saving of 535 tonnes of CO2 versus baseline levels, an average of 118.9kg/m3. The overall substructure design was completed ahead of time and to budget, with significant carbon savings.

The technology was also used on a major office construction project in London, which was designed to be highly sustainable, offering an example of how carbon emissions can be reduced within the construction process. The scale of the project meant the construction would span several seasons; therefore the chosen mix would need to be altered throughout to achieve the required performance for the weather conditions.

Providing four mix designs, Tarmac carried out a calibration process before pouring began. This showed that a lower-carbon concrete mix than the one initially selected by the contractor would meet the required performance at the current temperature, saving 25kg of CO2 per cubic metre before pouring commenced.

When the ambient temperature began to rise in the spring, CEVO Digital data was used to alter the mix once again, this time achieving a carbon reduction of 50kg/m3 compared with baseline levels.

As the construction industry ramps up to deliver the Government’s housing and infrastructure plans, deliverability shouldn’t come at the expense of sustainability. Employing digital concrete technology can optimize build programmes while delivering significant carbon savings.

• Subscribe to Quarry Management, the monthly journal for the mineral products industry, to read articles before they appear on Agg-Net.com