Question 1

How much CO2 can neustark store in the concrete?

Accepted Answer

Around 10 kg of CO2 can already be permanently stored in one cubic meter of fresh concrete. By 2025, we will be able to increase this value to over 150 kg of CO2 per cubic meter. Each unit of fresh concrete will then bind at least the same amount of CO2 that is released during its production – climate-neutral concrete becomes a reality.

Question 2

How does it work?

Accepted Answer

Concrete aggregate obtained from the demolition of buildings are mixed with CO2 captured from the atmosphere. Through so-called mineralization, the carbon dioxide is permanently bound. The concrete aggregate treated in this way is added to the fresh concrete as a gravel substitute. Concrete mixtures can be optimized with the target to reduce the amount of cement towards a regulatory minimum. And less cement equals less CO2 emissions.

Question 3

Why is it beneficial to use reclaimed concrete material?

Accepted Answer

Concrete aggregate, i.e. crushed concrete from demolished buildings, has an extremely large surface area due to its countless microparticles. Additionally, it contains large amounts of calcium hydroxide minerals, which can bind CO2. This makes the material highly reactive. Even without further treatment, concrete granules form stable chemical compounds with the CO2 (carbonate or limestone).

Question 4

What difference does it make if I choose concrete produced with neustark technology?

Accepted Answer

By using neustark concrete in your next construction project you will remove CO2 from the atmosphere that has been released in the past permanently store this CO2 in the concrete used for your new building, and lower the additional carbon dioxide emissions by reducing the amount of necessary cement in the concrete mix to a minimum.

Question 5

What percentage of recycled aggregate can be added?

Accepted Answer

That depends not only on neustark but also on the existing processing infrastructure at the concrete plant. Some partner concrete plants with appropriate screening and silo facilities have successfully produced using 100% recycled material. In any case, the economic and ecological optimum depends on the location and varies from concrete plant to concrete plant.

Question 6

And how is your own CO2 footprint?

Accepted Answer

For every 1,000 kg of CO2 stored in neustark granules, only 30 - 50 kg of new CO2 is emitted during the enrichment process. So we remove at least 20 times more CO2 from the atmosphere as we emit during the storage process.

Question 7

Exactly how much CO2 do you store in concrete? What quantities does that correspond to? Give us some comparisons.

Accepted Answer

Currently we can store 100kg CO2 per hour in concrete granules with one of our pilot plants. Fast growing spruces / firs absorb about 20kg of CO2 per year per tree. So one neustark plant can do in one hour what 5 trees need a whole year for. In other words, within 24 hours a single neustark plant can store the same amount of CO2 in concrete granulate as is released on average within a year of heating a single-family home with oil in Switzerland.

Question 8

Is there enough concrete deconstruction material to generate an impact?

Accepted Answer

Yes. According to neustark calculations, around two billion tons of deconstructed concrete material can be expected globally every year. This makes concrete the world's largest waste stream ever. Based on past construction activities, the amount is expected to double every ten years.  This material stream thus has the potential to store around 500 million tons of CO2 annually by 2050. Most of the global concrete deconstruction occurs in highly developed countries which built a large part of their ageing infrastructure from concrete.

Question 9

I want to understand all of this in more detail.

Accepted Answer

No problem. When concrete is exposed to a CO2 atmosphere, the Ca(OH)2 of the cement phases transforms into the thermodynamically stable form CaCO3 - and thus binds CO2. This phenomenon is well researched and known in the construction industry as natural mineralization or carbonation. neustark accelerates the mineralization process from over 1000 years to just a few hours, thereby quintupling the average CO2 uptake. More information on the process can be found here: General overview of the concept of mineralization:  Geoscienceworld Specific overview on carbonation of mineral wastes In-depth on mineralization of concrete granules Overview of material properties of mineralized concrete granules

Question 10

How can I be sure that the CO2 is actually contained in the aggregate?

Accepted Answer

On the basis of measurements. In our process, we measure the CO2 uptake of around 10kg per ton of demolished concrete using both a scale and a CO2 flow measurement. These two independent measurement methods reliably produce the same results so you can be sure the CO2 is bound in the concrete granules.

Question 11

Doesn't the mineralization in the concrete cause the steel to rust?

Accepted Answer

No. The reason why steel rusts is that the carbonation of CO2 in the pores of conventional concrete changes its pH value (it becomes more acidic). With neustark, carbonation takes place before the granules are mixed with cement. The pH value of the finished concrete is the same as that of conventionally produced concrete.

Question 12

What is the capacity of your plants?

Accepted Answer

Currently, one pilot plant mineralizes around 20 tons of concrete granules per hour. With additional modules, the output can be increased to over 100 tons of concrete granules, which is sufficient even for very large construction material recyclers.

Question 13

Can I scale up production at a later date?

Accepted Answer

Of course, you can always add an additional module to our current plant and thus double your production capacity. In addition, we are currently working on a 2nd type of plant that will complement our plant type 1. From 2025 onwards, this additional technology will allow you to increase the capacity of your plant many times over. Instead of 10kg of CO2 today, you will then be able to store up to over 150kg of CO2 per cubic meter of fresh concrete. The new plants do not compete with today's plants, but complement them.

Question 14

From which sources does the CO2 you use come?

Accepted Answer

From the atmosphere. CO2 is extracted from the air by our partners either in a biogenic process or through direct air capture. Together with our logistics partner, we guarantee the supply of CO2 to your production site. Within Switzerland we deliver it in a climate-neutral manner using biogas-powered trucks.

Question 15

Does the concrete suffer any loss of quality as a result of the mineralization?

Accepted Answer

No. The concrete is produced in accordance with the usual market standard and therefore meets all relevant quality criteria such as workability, compressive strength, modulus of elasticity and durability.

Question 16

How much cement can I save with neustark?

Accepted Answer

That depends on the recipe you use for the production as well as on the nature of the demolition aggregate which is to be enriched with CO2. Ideally, you can reduce the amount of cement in your concrete recipe to the regulatory minimum without compromising the quality of the concrete. We support you in optimizing your recipe.

Question 17

Is the CO2 released back into the atmosphere once a building built with neustark concrete is demolished?

Accepted Answer

No. The CO2 is converted into limestone in the process and remains in the concrete indefinitely, even if the concrete structures are later demolished. Thanks to neustark technology, concrete becomes a permanent CO2 sink.

Question 18

Are there no better CO2 sinks?

Accepted Answer

There are natural CO2 sinks, such as the forest and the soil and there is underground storage of CO2. Natural sinks do not permanently bind the CO2. With neustark technology, the CO2 is irreversibly bound and never returns to the atmosphere all by creating an added value in a useful product. Not one but each and every CO2 sink technology needs to be deployed right now because time is pressing and we need to remove as much CO2 as possible from the air as quickly as possible and bind it permanently. neustark currently offers one of the few functional solutions in Switzerland that makes this technically possible.

Question 19

Wouldn't it be cheaper to compensate for Swiss CO2 emissions abroad?

Accepted Answer

This may be the case in the short term, but where will the urgently needed future-oriented innovation and value creation take place? The parliamentary draft for the total revision of the CO2 law also specifies that 75% of the CO2 reductions to be implemented by 2030 must take place domestically, i.e. in Switzerland.  So compensation won’t be the solution.

Question 20

Is it even possible to build climate-positive with concrete?

Accepted Answer

Concrete essentially consists of aggregate and cement, with cement production in particular having a negative impact on the climate. Today, around 10 kg of climate-damaging CO2 can already be permanently stored in the aggregate used to make one cubic meter of fresh concrete. By 2025, we can increase this figure to over 150kg of CO2 per cubic meter. Then, each unit of fresh concrete will bind at least the same amount of CO2 that is released during its production. Ideally, neustark is used in combination with a CO2-reduced or even climate-neutral cement - then, at the latest, not only climate-neutral but climate-positive concrete will become a reality.

Question 21

How does neustark behave in relation to other environmental innovations in the concrete and building materials sector?

Accepted Answer

The vast majority of environmental innovations in the concrete sector are aimed at using less concrete, producing concrete with less cement, or reducing CO2 emissions in cement production. neustark is compatible with these efforts and is ideally used in combination with them.

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