The concrete industry, together with cement manufacturers, has developed a range of low-carbon products to meet the industry's need to reduce its carbon footprint. However, many customers are still wondering whether there are risks involved in new types of concrete and whether they dare to use them. The concern is understandable, but unnecessary.
In addition to low-carbon concretes, the BY-Low-Carbon Classification® has also been developed to promote their introduction. It offers an extremely clear, easy-to-understand and reliable way to determine and demonstrate the low-carbon degree of each product. The classification has recently been expanded to also cover blocks and landscape concrete products in addition to the previous ready-mixed concrete and element concrete. Just around the corner is the expansion of the classification to reinforced concrete piles, although they are already a very low-carbon way to implement pile foundations. A calculator that can reliably determine the climate emissions of an entire element is also being completed around the turn of the year.
In discussions, especially with developers, doubts about the potential risks of low-carbon products occasionally arise. This is understandable, for many reasons. The builder always carries a heavy responsibility, and this makes industry players cautious about everything new. From time to time, attempts have been made to create products resembling low-emission concrete from very special raw materials, and the end product has been called a neologism geopolymer. However, these products are not concrete.
Low-carbon concrete meets all the same familiar standards that are set for traditional concrete, and there is nothing new in the recipes for low-carbon concrete – that is, ingredients that have not been used for decades. There is over 50 years of experience in using the key component behind low-carbon, blast furnace slag from the steel industry, as an admixture in concrete. A more recent admixture, limestone powder, is nothing more than very finely ground stone.
On this basis, it is easy to be convinced and reassured that the use of low-carbon concrete does not involve the worry that the product will start to reveal something unexpected and unpleasant over decades of use. Low-carbon concrete according to the BY-Low-Carbon Classification® is as safe to use in all applications of concrete as traditional concrete.
Winter concreting methods also work with the characteristics of low-carbon concrete
As for the slower strength development of low-carbon concrete, there is nothing new in it. The matter can be helped quite easily with traditional, familiar tricks.
Finnish builders are top professionals in winter concreting. We can successfully cast and harden concrete even in cold conditions. Casting at temperatures of -20 degrees Celsius is not an impossibility, but an everyday occurrence in a harsh winter.
If you want to boost the strength development of low-carbon concrete, ready-made solutions can be found in winter concreting. You just need to get used to these tricks when you are already used to high outdoor temperatures. Raising the temperature of the hardening concrete accelerates the strength development of concrete made from blast furnace slag cements.
Since energy in Finland is very low-emission, heating the concrete or the work site does not negate the emission reduction achieved by the low-carbon nature of the concrete. According to calculations, even moderate heating rarely increases the carbon footprint of construction by more than a tenth compared to the large emission reduction achieved by using low-carbon concrete.
The first binding national requirements for the carbon footprint of buildings will come into force at the beginning of 2026. Low-carbon concrete, either cast on site or delivered as elements, is a safe way to build in a low-carbon way.
Jussi Mattila
CEO, Betoniteollisuus ry
jussi.mattila@rt.fi + 358 40 063 7224Construction product industry RTT ry, Betoniteollisuus ry
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