FAQ

Frequently Asked Questions


What exactly is CarbonCure?

CarbonCure manufactures a technology that is installed in masonry and ready mixed concrete plants to recycle carbon dioxide (CO2) in order to make better concrete products. CarbonCure also provides services to its concrete producer customers to help them better access the growing green building market.


Where does the CO2 come from?

Our concrete producer partners source waste carbon dioxide (CO2) from local industrial gas suppliers. These suppliers collect emissions from the smokestacks of nearby industrial facilities such as oil refineries, coal plants and fertilizer plants. The CO2 is collected and purified, and then made available for commercial applications such as beverage production, steel manufacturing, and now concrete production. Contact your local CarbonCure manufacturer to find out where their supply of CO2 is sourced from in your region. 


Why does recycling CO2 into concrete matter?

The critical ingredient in concrete is cement, and cement production accounts for about 5% of global greenhouse gas emissions. While CO2 is a safe substance (humans breath in oxygen and breathe out CO2), there has been too much CO2 created through industrial processes and transportation, and this is causing negative effects on our environment. One of the most viable solutions to reduce carbon emissions is what’s known as “carbon capture and utilization”, where CO2 is captured and used to make better products. CarbonCure’s process is a form of carbon capture and utilization, since the technology uses CO2 to improve the properties of concrete.


Does the CO2 escape from the concrete when it’s demolished? 

Carbon dioxide that is added to the concrete during the mixing stage reacts with calcium in the cement, and becomes chemically converted into a calcium carbonate mineral. Since the CO2 has been converted into a mineral, it will never escape because it no longer exists. Concrete manufactured using CarbonCure’s technology behaves the same as traditional concrete when demolished.


How much CO2 is recycled into the concrete products?

The amount of CO2 introduced into concrete is customized for each producer in order to optimize concrete’s performance. On average, CarbonCure’s masonry producer partners recycle about 15 grams of carbon dioxide into each block (approximately 0.03 lbs). Ready mixed concrete producers recycle about 600 grams CO2 per m3 concrete (1lb CO2 per yd3). Additional CO2 may be saved elsewhere as a result of optimizing the concrete mix. A small amount of CO2 will be created through the process, and this penalty is considered in CarbonCure’s carbon accounting procedures. CarbonCure always completes a cradle to gate lifecycle assessment in order to calculate the net carbon benefit to a product or building project.


Considering the emissions from processing and transport of CO2, does this negate CarbonCure’s positive environmental impact?

CarbonCure conducts a cradle to gate lifecycle assessment of the materials and energy used to produce our technology, its transport to the concrete plant, and the energy required for processing and transport of the CO2 to the concrete plant. Typically these factors amount to emissions that total about 10% of what CarbonCure introduces into the concrete. For example, 195,000 concrete blocks by Ernest Maier were installed in the MGM National Harbor development near Washington DC. These blocks sequestered 3,670 lbs of CO2, but 520 lbs CO2 were emitted for additional processing and transportation. Thus, the net benefit to the environment was a carbon reduction of 3,150 lbs CO2.


What is the environmental benefit of using concrete made with CarbonCure instead of regular concrete?

In ready mixed concrete, the use of the CarbonCure system can result in an offset of roughly 5% of the carbon emissions associated with concrete’s manufacture. This benefit is gained by introducing a small amount of CO2 in concrete to increase the materials’ early strength, which creates an opportunity for producers to optimize their concrete mixes–this may include reducing the cement content, or increasing the use of cement alternatives such as fly ash or slag.

In masonry, the addition of CarbonCure helps to offset approximately 1% of the carbon emissions of a block’s manufacture. While some manufacturers can find small material strength benefits, masonry is already very lean on cement and is able to achieve compressive strength standards with low cement content. While a 1% offset is still a long way from our goal of helping to develop carbon-neutral concrete, it’s still 1% above and beyond anything thought possible before.

The way we see it, any building project that’s using concrete products but isn’t incorporating recycled CO2 into the mix is a missed opportunity to reduce the amount of CO2 present in the atmosphere.


Does CarbonCure contribute to LEED points?

Yes, CarbonCure may contribute to LEED points. In LEED 2009, CarbonCure may be used as part of an Innovation in Design credit submission. Under LEED v4, CarbonCure can contribute toward 3 material credits:

  • Building Life Cycle Impact Reduction – CarbonCure helps reduce the carbon impact of a project
  • Building Product Disclosure and Optimization: Environmental Product Declarations – Upon request, EPDs can be created for CarbonCure products
  • Building Product Disclosure and Optimization: Material Ingredients – Upon request, HPDs can be created for CarbonCure products

Interested in EPDs/HPDs for your project? Please contact your local CarbonCure producer for details.


Does the CarbonCure process impact concrete’s colour or texture?

The addition of CarbonCure to concrete has no impact on a manufacturer’s ability to add colour or finishes, nor does it change concrete’s texture. In fact, masons, truck drivers and quality control personnel say they can’t tell the difference between a CarbonCure product and a regular concrete product.


How does carbon dioxide improve the compressive strength of ready mixed concrete?

The CarbonCure technology typically results in an average 10% improvement in early compressive strength for ready mixed concrete. This strength improvement varies across different concrete producers due to variations in equipment, mix design, climate and other factors. The mechanism that creates a strength benefit is the subject of continued investigation. The positive impacts such as accelerated hydration and improved compressive strength are, however, analogous to what researchers have previously observed when studying the addition of calcium carbonate nanoparticles to cement and mortar.


Isn’t carbonation in concrete bad? How is this different? What about the impact on pH?

CarbonCure’s process is a treatment applied to fresh concrete during production and is distinctly different from the traditional atmospheric carbonation of mature concrete. Atmospheric carbonation affects the pH of finished concrete over time, which may have negative effects on the concrete’s quality over many years. CarbonCure’s process introduces CO2 into the concrete during the mixing phase, where the CO2 immediately becomes chemically converted into a calcium carbonate mineral. The CO2 utilization has no impact on concrete alkalinity. The pH remains sufficiently high to ensure adequate protection of ferrous reinforcement. More details can be found in a technical note.


Can CarbonCure concrete be used with steel reinforcement? What about corrosion of the steel?

Yes, CarbonCure concrete may be used in the same applications as regular concrete, including the use of steel reinforcement. Because the CO2 has been chemically converted into a calcium carbonate mineral, it will not contribute to the corrosion of steel.


How many manufacturers does CarbonCure have? Where can I get CarbonCure concrete? 

A detailed list of our manufacturers can be found on our producers page.


How do I use CarbonCure on my project?

CarbonCure specification language is available for construction Division 3 and Division 4 specifications. Our spec language can be viewed on our specifications page.

 

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