How concrete can become a carbon sink

Amplifies positive effects

RISE has implemented several initiatives to develop methods to further strengthen and take advantage of the positive effects of concrete carbonation. According to conservative calculations, concrete structures in Sweden absorb around 300,000 tonnes of carbon dioxide per year, but according to Malaga, there is great potential to significantly increase uptake. For example, by handling demolition materials better, absorption could be doubled to 600,000 tonnes a year. When construction waste is crushed, the waste should be spread out so that it is exposed to air for maximal carbonation. Then it becomes a carbon sink while the material can be used for new concrete and other products.

– “When designing structures, it’s also important to understand how carbonation works,” says Malaga. “The material must be reactive, which means it’s important in the design process to leave surfaces open so that they can absorb carbon dioxide from the air.”

Utilising a natural process

RISE develops strategies for concrete carbonation with the goal of speeding up the natural carbonation process. By enhancing these types of methods, it is possible to create carbon sinks that have a time span of no less than 100-150 years. It thus becomes a relatively simple and inexpensive form of carbon capture and storage (CCS).

According to researchers at RISE, to make progress in this it is important to systematise measurement methods and calculations of carbonation capacity depending on the concrete composition and exposure environment. And knowledge among customers and decision-makers needs to increase.

– “One way would be to ensure that calculations of natural carbonation are included in the climate declarations that serve as a basis for standards bodies,” says Malaga.