Lower embodied carbon
Industry figures put CEM III/A at roughly 30% to 60% less CO2 per tonne of cement than CEM I, depending on the slag content.
CEM III/A cement
Low Carbon Concrete (CEM III/A)
Concrete made with CEM III/A blastfurnace cement, mixed fresh on your site.
Trusted by contractors, councils & developers
CEM III/A is a blastfurnace cement. Between 36% and 65% of the Portland clinker is replaced with ground granulated blastfurnace slag (GGBS), a by-product of iron making. Clinker is where most of the carbon in concrete comes from, so swapping it out lowers the embodied CO2 of every cubic metre. CEM III/A is available from every Procon depot. We carry it on our volumetric mixers and batch it at your pour, so you get a lower carbon mix with the same on-site control as any other job we do.
Durable in aggressive ground
GGBS concrete is denser and less permeable, with better resistance to chloride and sulfate attack.
Cooler in big pours
Lower heat of hydration reduces the risk of thermal cracking in thick slabs, bases and mass fill.
Mixed fresh, metered exactly
Batched on site like every Procon pour. You pay for the volume you use and nothing goes back to the yard.
Low Carbon Concrete at a glance
- Cement type
- CEM III/A blastfurnace cement to BS EN 197-1
- GGBS content
- 36% to 65% of the cement, replacing Portland clinker
- Embodied CO2 (cement only)
- About 350 to 594 kg CO2e per tonne, against about 860 kg for CEM I (Mineral Products Association, Fact Sheet 18)
- Strength gain
- Slower at 3 and 7 days than a CEM I mix; design strength is assessed at 28 days as normal
- Colour
- Paler than a CEM I mix
- Standards
- Mixes specified to BS EN 206 and BS 8500
- Availability
- From every Procon depot, mixed on site by volumetric wagon across Yorkshire and the North West
Where low carbon concrete earns its place
Contracts with a carbon target
Main contractors and public sector clients increasingly ask how a scheme reduces embodied carbon. Specifying CEM III/A on foundations, slabs and drainage is one of the simplest reductions to make, with no change in how the concrete is placed.
Foundations and below-ground work
Footings, ground beams, pile caps and drainage surrounds, where the better chloride and sulfate resistance of GGBS concrete is useful and early strength rarely holds up the programme.
Thick slabs, bases and mass fill
Large pours generate heat as they cure. The lower heat of hydration of a CEM III/A mix keeps peak temperatures down and reduces the risk of thermal cracking.
What low carbon concrete costs
CEM III/A is priced per cubic metre like any other mix we supply.
- Billed on the volume actually mixed, with no part-load charges.
- We will price it side by side with a CEM I mix of the same grade so you can compare.
- The cost to plan for is usually programme rather than material: allow for slower early strength when striking formwork or loading a slab.
Ask about our current CEM III/A rate. Send the grade, volume and site postcode, or call 0800 001 6147.
Where we deliver
Low Carbon Concrete across Yorkshire and the North West
We run low carbon concrete out of three depots. If your site is inside these postcode areas, ring us and we will tell you which depot is closest and roughly how long it takes to reach you.
Get a volumetric concrete price in 30 minutes
- BS EN 206 Compliant
- Same-Day Available
Questions
Low Carbon Concrete: your questions answered
The things customers ask us most about low carbon concrete.
What is CEM III/A cement?
CEM III/A is a blastfurnace cement defined in BS EN 197-1. It contains between 36% and 65% ground granulated blastfurnace slag (GGBS), with Portland clinker making up most of the rest. Because the slag replaces clinker, which is the carbon-intensive part of cement, it has a lower embodied carbon than CEM I Portland cement.
How much carbon does CEM III/A save?
Mineral Products Association figures give CEM I Portland cement about 860 kg CO2e per tonne, and CEM III/A between about 350 and 594 kg per tonne depending on how much slag it contains. That is roughly 30% to 60% less per tonne of cement. The saving per cubic metre of concrete depends on the mix and how much cement it uses.
Is low carbon concrete as strong as normal concrete?
At 28 days, which is when concrete strength is specified and tested, a CEM III/A mix is designed to reach the same strength class. It gets there more slowly. Early strength at 3 and 7 days is lower, so allow more time before striking formwork or putting load on a slab, especially in cold weather.
Can I use CEM III/A concrete in winter?
Yes, but plan for it. Slag cements gain strength more slowly at low temperatures, so curing and protection matter more than with a CEM I mix. On a programme where early strength is critical in cold weather, talk to us about the right mix before you book.
What is the difference between CEM III/A and GGBS concrete?
They are two routes to a similar result. CEM III/A is a factory-blended cement with the slag already in it. GGBS can also be added to Portland cement at the concrete plant, which BS 8500 calls a cement combination. Both lower the clinker content of the mix and so its embodied carbon.
Does low carbon concrete look different?
Slag cement concrete is usually paler than a CEM I mix, and it can show a blue-green tint in the first days after the pour that fades as it dries. That matters on exposed decorative finishes, and makes no difference on foundations or covered slabs.
Other Procon services
Volumetric Concrete 24/7
Volumetric concrete. Mixed on your site. Pay for what you pour.
Same-day where we can, fresh every pour, across Yorkshire and the North West.
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