What is volcanic ash?
Volcanic ash, or pumice, as it is essentially, forms when lava rapidly cools and hardens during explosive volcanic eruptions. This natural pozzolan has been found to possess properties similar to cement but with significantly lower carbon dioxide emissions.
After numerous studies and tests at C-lab, a part of Thomas Concrete Group, it has been confirmed that finely ground pumice exhibits excellent binding properties and behaves similarly to coal fly ash.
The potential of pumice in concrete
The hope is that finely ground pumice can replace a large portion of cement in concrete, significantly reducing concrete’s carbon footprint. Unlike fly ash, whose availability decreases as coal-fired power plants are phased out, there is ample supply of pumice as long as there are active volcanoes.

Bright prospects
Pumice is already approved as a binding material in concrete in the United States and parts of Europe. Now, the Swedish construction standard needs to be updated for pumice to be used in Sweden as well. A consultation has been sent out and is expected to be finalized and published as an official Swedish standard shortly.
Ambition for 2025
Our ambition is for Thomas Concrete Group to be able to deliver the first low-carbon concrete with pumice as a binding material by 2025. This development is a significant step towards more sustainable construction.
A call to the construction industry
We encourage all stakeholders in the construction industry to join us on the journey towards a greener tomorrow. By choosing low-carbon concrete, we can collectively contribute to a significant reduction in the construction sector’s carbon footprint and pave the way for a sustainable future for generations to come.