World’s first carbon-eating concrete blocks are weeks away from commercial use

Now, with the global market in green building materials expected to surpass 711.06 US billion dollars by 2030 (from 270.26 billion dollars in 2020), concrete users concerned with the environmental impact from cement are looking for reliable materials that allow them to reduce cement use.

One Montreal-based technology company, called CarbiCrete, is doing just that by producing an alternative concrete that absorbs carbon dioxide instead of releasing it into the atmosphere.

Interesting Engineering (IE) spoke to the chief marketing officer (CMO) of CarbiCrete, Yuri Mytko, to find out exactly how it works.

Commercializing a process that enables cement-free, carbon-negative concrete production

Cement, or more specifically Portland clinker, acts as a bonding agent in concrete, and is a major source of global carbon dioxide emissions. During production, limestone (CaCO3) is “calcinated” at high temperatures in a cement kiln to produce lime (CaO), leading to the release of waste CO2.

In addition, the process requires a very high heat, or around 1,400 degrees Celsius, often generated using a fossil fuel source to heat the limestone. The limestone disintegrates under the heat, releasing more carbon dioxide.

Carbicrete aims to change that by commercializing a process enabling cement-free, carbon-negative concrete production. Its patented carbon removal technology uses industrial by-products and captured carbon dioxide.

"For every ton of concrete produced using the CarbiCrete process, 150 kg (kilogram) of CO2 are abated/removed," Yuti Mytko tells IE.

The novel technology can be implemented in existing concrete manufacturing plants

The company offers concrete manufacturers the process and support to implement this replacement technology in their existing plants. Mytko explained to IE that the process is identical to that of cement-based concrete-making with two key differences.

One is that ground steel slag, a by-product of steel-making, replaces cement in the mix, which acts as the binder. Additionally, the concrete is cured with CO2 instead of heat and steam in a specialized, sealed absorption chamber, where the curing can occur.

During this carbonation process, the CO2 is permanently captured and converted into stable calcium carbonates, filling the voids of the matrix to form a dense structure and giving the concrete its strength.

Concrete blocks, or CMUs (concrete masonry units), are created by pouring the mixture into a traditional block-making machine.

According to the company's website, the concrete reaches full strength within 24 hours.

Alternative precast blocks are 30% stronger than cement-based ones

This technology makes it possible to produce a variety of precast building materials. Mytko reveals that these include construction blocks that are up to 30 percent stronger (in compressive strength) than conventional, cement-based blocks.

The chief marketing officer claims that since steel slag, which is typically regarded as waste, is used in place of cement in their procedure, the blocks are also less expensive. The CMUs, also display better freeze/thaw resistance. Overall, they offer the same, if not better, quality and performance than traditional masonry blocks - all with a much lower carbon footprint.

"Each block of 18kg represents up to 3kg of CO2 abated/removed than conventional, cement-based blocks," explains Mytko, further clarifying that the CMUs have been designed with sustainability in mind.

A collaboration with a Quebec concrete manufacturer will yield the world's first commercially-available carbon-negative concrete blocks

According to The Globe and Mail, Carbicrete will increase manufacturing to 25,000 units per day thanks to a partnership with Quebec-based concrete manufacturer Patio Drummond. The industrial-scale pilot project will be housed in Drummond's precast facility in Drummondville, Quebec.

"Production is set to begin in the coming weeks and will yield the world's first commercially-available carbon-negative concrete blocks," Mytko told IE.

The scaling up comes after CarbiCrete received a $3.15 million dollar grant from the Technoclimat program of the Quebec government in 2020, which is run by the Quebec Ministry of Energy and Natural Resources.

The government also assisted in COVID-19 relief in the amount of an extra 150,000 dollars. The grant was made in conjunction with $2.1 million grant awarded to CarbiCrete by Sustainable Development Technology Canada, which was used to finance a demonstration program, and an earlier $3 million investment, in December 2019, from the Environmental division of Harsco Corporation.

"The [Quebec] Ministry of Energy and Natural Resources' support will play an important role in the accelerated development of our technology. The deployment of which will bring a sustainable and cost-effective solution to the emissions associated with cement production," Chris Stern, CarbiCrete CEO, states on the company website.

As far as next steps, Mytko reveals to IE that CarbiCrete are very much focused on getting the commercial phase of their pilot in Drummondville, Quebec, up and running.

Carbicrete plans to license its technology to manufacturers around the world

Since Carbicrete's process can be integrated into any existing concrete production plant, the company intends to license its carbon-negative concrete technology to manufacturers worldwide.

Until then, we know that the construction industry has other options to chose from, including CarbonCure (also a Canadian company).

Earlier this year IE reported that the carbon tech's material attracted a lot of attention since acquiring a large investment from Amazon's two billion dollar Climate Pledge Fund in 2020.

CarbonCure claims their resulting cement is stronger than conventionally manufactured concrete, too, so builders can use smaller amounts of it in their mixes. According to the company, CarbonCure concrete leaves a five-percent smaller carbon footprint than conventional concrete.

CarbonCure's concrete technology is already being used worldwide in about 400 concrete plants. The company adds recycled carbon dioxide to its formula, although CarbonCure's concrete does contain cement.

A misconception addressed

Yuri Mytko revealed to IE that the company frequently runs into misunderstandings from others about what steel slag (their feedstock) is.

"It is not the same thing as iron slag, which has been used in concrete-making for decades," the CMO explains.

In an email response Mytko provided the following facts outlining the key differences:

Food for thought: What about concrete's other major component, sand?

Widespread use of concrete is exhausting our diminishing supplies of useable sand. And no, not the desert-type sand, which is useless for producing concrete due to its smooth, rounded shape.

The sand used in concrete production is often referred to as sharp sand. It has a course and grainy texture and comes from ground quartz rocks, sometimes with clay and iron added.

In the preparation of concrete (made with cement, water, sand, and gravel), for each tonne of cement, the building industry needs about six to seven times more tonnes of sand and gravel, according to GreenFacts.

"Concrete is almost 50 percent sand, and until you find a sustainable source for the sand, concrete cannot be labeled 'sustainable'," highlights one user of The Globe and Mail.

Humanity's claim to cement its relationship with its environment has failed miserably, but companies like CarbiCrete provide hope.