KIBECO concrete. Concrete stores CO2.

The KIBECO building materials (RC concrete and RC gravel mixtures) consist of 100% recycled Swiss aggregate, permanently bound carbon dioxide and cement produced in accordance with SN EN 197-1. The KIBECO building materials treated with the Neustark process meet all standard-relevant quality criteria such as compressive strength, modulus of elasticity and durability. KIBECO building materials do not differ from the usual RC building materials in terms of processability and colour. The KIBECO building materials store CO₂ permanently and sustainably and can also be recycled or further treated by the next generation without risking CO₂ release.

Unlike conventional concrete, KIBECO concrete contains around 10 kg/m3 of stored CO₂ and recycled aggregate. You can achieve a lower carbon footprint with KIBECO concrete than with conventional concrete.

The revolutionary climate-friendly KIBECO concrete is a development of ETH spin-off Neustark. Neustark has developed an efficient solution for irreversibly storing carbon dioxide (CO₂) from the atmosphere in recycled building materials. The raw material thus treated can be fed back into the cycle and used together with sustainable cement (Susteno 4, CEMII/B-LL) for the production of climate-friendly structural concrete and RC gravel mixtures. 

Concrete granulate extracted from the dismantling of buildings is treated with carbon dioxide separated from the atmosphere. Mineralisation permanently binds the CO₂ in crystalline form. The concrete granulate thus treated is added to the fresh concrete as a gravel substitute.

The Neustark process enables permanent storage of 10 kg of climate-damaging CO₂ per cubic metre of fresh concrete.

An average single-family home uses around 300 m3 of fresh concrete. If the house is built with KIBECO building material and delivered with a KIBECO electric mixer truck, 3 tons of CO₂ can currently be permanently removed from the atmosphere. This corresponds to a distance of around 15,000 km with a mid-range petrol engine!

A comparison: a beech has to grow for around 80 years to absorb one tonne of CO₂ (source: co2online/carbon-connect). In addition, the trees may be burned at the end of their lives releasing the CO₂ they had absorbed over the years. In contrast, the mineralisation of CO₂ in concrete granulate through the Neustark process guarantees permanent CO₂ storage.

Generally speaking, the CO₂ used industrially in Switzerland comes from abroad. We do it differently. We obtain 100% of the CO₂ we use from the atmosphere in Switzerland. The CO₂ is extracted from the atmosphere through a biogenic process at the Bern wastewater treatment plant in Herrenschwanden. The CO₂ is then delivered to our production facility in a climate-neutral manner by biogas-powered trucks.

When a concrete wall is exposed to air, the carbon dioxide [CO₂] reacts with the calcium compounds in the cement phases [Ca(OH)2] and forms calcite crystals [calcium carbonate, CaCO3]. CO₂ is thus permanently bound in the crystals (mineralised). This naturally occurring reaction, also known as “natural mineralisation” or “carbonation,” is well known in the construction industry and is accelerated and multiplied in the process developed by Neustark.

The CO₂ uptake of 10 kg per tonne of concrete granulate is measured and documented in the Neustark process using both a CO₂ flow measurement and a balance, whereby the two independent measurement methods reliably lead to the same measurement result.

No. The reinforcement rusts in the concrete because the concrete becomes more acidic during the natural mineralisation process and the pH value is reduced as a result. Carbonation by the Neustark process takes place before the granulate is mixed with cement and water. The pH value thus remains the same as for non-mineralised concrete.

A natural process:

the main constituent of cement is calcium oxide [CaO]. It is extracted from limestone, which mainly consists of calcite crystals [calcium carbonate, CaCO3]. The limestone is fired in the cement plant at around 1,400°C, which releases CO2: the calcium oxide [CaO] is left behind and is further processed into cement products. The cement is finally mixed with water, gravel and sand to form concrete.

CaCO3 --> CaO + CO2

When a concrete wall is exposed to air, the carbon dioxide gas [CO2] from the air reacts naturally with the calcium compounds in the cement phase [CaO]. In the fine pores and cracks, calcite crystals [calcium carbonate, CaCO3] form, which can permanently bind CO2. The natural reversal of the above-mentioned reaction thus occurs.

CaO + CO2 --> CaCO3

However, this is a slow process. During the life of a building, only a few millimetres of the concrete surfaces are carbonated.

Permanent CO2 capture:

CO2 is permanently captured by the formation of crystals (mineralisation). This naturally occurring reaction is known in the construction industry as carbonation and is accelerated and multiplied in concrete granulate through the Neustark process.

KIBECO building materials are thus permanent and sustainable CO2 storage vehicles and can also be recycled or further treated in the next generation without risking CO2 release.

No increased risk of corrosion of the reinforcement:

Carbonation with the Neustark process takes place before the concrete granulate is mixed with cement and water. The pH value thus remains the same as for non-mineralised concrete. This means the risk of corrosion remains the same as with conventional concrete.

CO₂ storage fills voids in the recycled granulate, making the material denser. This not only improves the material properties, but also leads to a higher modulus of elasticity comparable to that of primary concrete.

KIBECO concrete can be used for the same applications as conventional concrete without CO₂ sequestration. 

Like conventional concrete, KIBECO concrete is produced in the concrete plant and delivered to the construction site by mixer truck. It is placed in the formwork and post-treated as usual. No additional training is required for construction company staff.
Where possible, delivery is made with electric mixer trucks to reduce transport emissions. Using an electric mixer truck saves more than 12 kg of CO₂ eq. per 100 tonne-kilometres. That’s more than 60% of greenhouse gas emissions.

KIBECO concrete is already available in all regions via KIBAG. Please contact us directly for further information and orders.

The price difference varies depending on the project and requirements. You can find a detailed overview in our current price list under KIBECO. For more detailed information, please contact us directly.