Worlds first carbon negative concrete

The construction industry is an industry with massive greenhouse gas emissions, and concrete alone stands for around 7% of co₂ emissions globally.

Numbers from 2021
1,0 mill

Tons surplus wood is thrown away in Norway every year

1,8 mill

Of CO₂ emissions from burning this wood

5,0 mill

M³ concrete used in Norway a year

7%

Global CO₂ emissions form concrete worldwide.

Creating carbon negative concrete

What if you could make a carbon negative concrete?

What if you could use wood waste from the building industry to do so?

The construction industry is an industry with big greenhouse gas emissions, and concrete alone stands for around 7% of CO₂ emissions globally. If we are to honour our commitment in the Paris agreement Norway have to half our CO₂ emissions by 2030 compared to1990-levels. It is challenging to imagine that we will build less in the years to come, and even more so to imagine that we will find a material as versatile as concrete. Therefore, we must find more environmentally friendly solutions that allow us to build the future without contributing to making it less liveable for future generations. The construction industry must take part of this green change. Biocrete is a concrete revolution and a part of the solution to both our increasing CO₂ emissions the growing waste problem and, we’re developing the young Norwegian biochar industry.

What is Biocrete

In Norway we throw away 1 000 000 ton’s wood waste every year, most of this is burned for energy and some 1 800 000 tons of CO₂ is released out to the atmosphere. We want to pyrolyze wood waste from the building industry to get biochar. The excess heat from the pyrolysing process will be used in a district heating plant or in other heat-intensive processes. The biochar prodused contains more than 90 % carbon.Then we mix this into concrete to compensate for the CO₂ emissions from the concrete production, transport and rebar used and we have a carbon neutral product. The carbon will be locked in the concrete for al times. For every kilo of carbon we sequent in the concrete we save the atmosphere for 3,67 kg of CO₂. This is carbon storage. CCS.

Full-scale test.

In the project, we have developed a selection of concrete recipes with strength properties adapted to various areas of use. The properties of the concrete have been tested in a full-scale production off concrete walls and floor slabs.

The wall was designed as shell elements where the core was cast out after precasting the load-bearing outer walls. This was carried out at Con-Forms factory in Orkanger together with Betong Øst and NTNU. The amount of biochar used in the core concrete between the shell elements was adapted to fulfil the strength properties required for this purpose, where a somewhat lower strength concrete is used.

The purpose of the core concrete was primarily to achieve the castability of self-compacting concrete whilst incorporating a high content of biochar. We have also casted floor slabs for strength testing. The full-scale tests have proved successful regardingthe practical execution, the properties of the concrete, and the final achieved carbon negativity. Not only did the biochar compensate for the climate gas emissions of the concrete, but also for the reinforcing steel used as rebar.

We have made carbon neutral and even negative building elements in concrete.

Project Partners
Con-Form
Skanska
Oplandske Bioenergi
Betong Øst
Norsk Biokullnettverk
Snøhetta
Publications
August 2020
Sciencedirect
Effect of nanoparticles on properties of geopolymers designed for well cementing applications
2021