From glass to concrete: powering up building materials innovation

Concrete is ubiquitous, so is glass. While there is a tendency to take everyday materials – and the way they are produced – for granted, a massive shift in how we use resources is underway.

For concrete, the challenge is to find low-carbon alternatives to cement. For glass, a better approach to recycling is required. But what if these two objectives can be combined? What if post-consumer glass can help address the carbon footprint of concrete?

Answering such questions in the affirmative represents a “win, win, win,” says Steve Harpur, CEO of Progressive Planet. “The bottom line is that we can divert glass from the landfill and use it for cement, thereby replacing a very carbon-intensive product. We found that in the process, we also gain other valuable byproducts.”

The concrete conundrum

Across the globe, concrete is used to the tune of approximately 30 billion tonnes annually, primarily for infrastructure and construction. Concrete production is associated with significant greenhouse gas emissions, with one key ingredient – cement, essentially the glue that holds concrete together – being responsible for roughly 7 per cent of global carbon dioxide emissions.

That’s why low-carbon solutions for cement replacements represent a significant opportunity for achieving emission reductions, says Randy Gue, director and board member, Progressive Planet. “The demand for concrete has been extremely robust for many years. A lot of companies are currently using supplemental cementing materials to reduce the carbon footprint, but sources for these materials are starting to decline.”

Among the most commonly used supplemental cementing materials are fly ash and slag, byproducts of coal-fired electricity generation and steel production respectively. As coal plants are phased out and the steel industry pivots to more efficient production methods, local supplies of fly ash and slag are dwindling, notes Mr. Gue, who has worked in the cement industry for over 30 years, with a special interest in business development and cleantech innovation.

“Cement companies are looking for innovative ways to make up for the shortfall – and this represents an opportunity to reduce the carbon footprint of cement and concrete,” he says. “That’s where Progressive Planet comes into the picture. We have this innovative technology for creating a supplemental cementing material from post-consumer glass.”

Science and history

Progressive Planet’s journey to revolutionize the cement industry started in 2017, when Mr. Harpur noticed cement producers casting around for alternatives to fly ash. “We quickly figured out that the federal government’s deal with provinces to phase out coal-fired power would severely limit access to fly ash,” he recalls. “This wasn’t only happening in Canada – it was part of a global trend affecting one of the main alternatives to Portland cement in concrete’s binding mix.”

Closer examination of fly ash revealed that its main ingredient is amorphous silica – with a composition similar to natural pozzolans and glass. Long valued for use in building materials, it cropped up in Roman concrete, which was “used by Romans to build the Pantheon, which is nearly 1,000 years old and has a self-supporting oculus at the top,” says Mr. Harpur. Under his leadership, Progressive Planet went on to acquire a number of natural pozzolan mines.

“When we started testing for a performance attribute of cement called water demand, we found that adding glass to natural pozzolans could reduce water demand. Testing blends of these materials then morphed into using only glass,” he explains. “That’s when a light went off in my head: why don’t we mine urban glass?”

Mr. Harpur, together with his business partner David Richardson, had been immersed in urban mining since 2009, starting with a mechanical plant for separating food waste and other recyclables, such as cardboard, paper, plastics and tin.

“This was the start of the journey that led us to developing PozGlass, a technology for making new Roman concrete – and for using glass instead of natural pozzolan,” he adds.

Post-consumer glass recovery

The quest to reuse post-consumer glass led Progressive Planet to engage with John Lair, president and CEO of Momentum Recycling, a Utah-based company that started collecting glass in 2008 and opened its first glass recycling plant in 2012.

“One of the exciting things about the Progressive Planet project is that it uses a product that would otherwise go to the landfill,” says Mr. Lair. “When you recycle glass – and process it in the way we do – you’re unable to refine all of it. For a small percentage of glass, you can’t guarantee a certain purity or it is too fine, which makes it unsuitable for making containers or fiberglass insulation, the major uses for recycled glass.”

This means most glass recycling facilities are left with a waste product, which “Progressive Planet is going to turn into a beneficial product for the cement industry,” he says. “They are stepping in and bringing some unique processes and technologies to bear on getting value out of all of the glass – and that is going to make recycling better for everyone.”

For Mr. Harpur, Momentum Recycling represents not only a source for high-quality glass residue but also for advice on system design and equipment selection. “They’re helping us with phase one, the dry-processing of glass,” he says. “For phase two, we will use water. This process is quieter and more efficient – it also brings other benefits.”

Unlocking other business streams

In wet-milling the glass, a spike in the pH indicated the release of “sodium oxide, which then becomes sodium hydroxide,” says Mr. Harpur. “By combining sodium hydroxide with carbon dioxide from the flue stack, we create sodium carbonate.”

Another process combines sodium carbonate water with calcium chloride, a chemical that is harvested from oil sands and brine water, to create an ion exchange. The result is limestone.

“Our process takes post-consumer glass and converts it into PozGlass, which is used to make ‘New Roman concrete.’ And then, we combine chemicals with wastewater and flue gas to make a product that not only sequesters carbon permanently but also has a massive global demand,” he says.

The idea to advance a circular economy – and leverage material innovation for “products for a healthy planet” – have long inspired Progressive Planet’s business model and a product line that includes cat litter, industrial absorbents and animal feed additives since 1989.

Partnering for impact

There has been a shift in the building materials industry towards reducing the carbon footprint associated with materials production. By reusing materials that would otherwise be part of the waste stream, Progressive Planet’s innovation brings opportunities for advancing a circular economy model – and these efforts have attracted attention from Lafarge Canada, a leader in innovative and sustainable building solutions.

“Sustainability has always been a priority for Lafarge,” says Stephanie Voysey, head of sustainability and environment, Western Canada, at Lafarge. “While we’ve made substantial progress with our products, industry-wide acceptance of low-carbon building materials remains challenging. At the same time, we also require multiple solutions to offset the declining availability of supplementary cementitious materials like slag and fly ash.”

For Ms. Voysey, PozGlass represents the potential for “moving the needle in sustainability. It’s an exciting new innovation we are very interested in.” Among the key attributes that make a new product attractive to Lafarge is its ability “to be integrated into the marketplace without negatively impacting customer expectations,” she explains. “For example, we prioritize consistency in material quality, workability and strength. If a change is introduced, it should always be beneficial.”

Mr. Harpur sees the engagement of industry partners as an essential step. “You can have the best technology in the world, but if you can’t reach the consumer or user, your product doesn’t have value,” he says. “Having a partner like Lafarge allows us to move forward in a timely fashion and prove that this is a viable supplemental cementing material.”

Idea generation facility

Progressive Planet recently secured $4.6-million in funding, distributed over four years, from Sustainable Development Technology Canada. The goal is to build a pilot plant, and Mr. Harpur envisions the facility as a catalyst for generating ideas.

“What excites me most about building the pilot plant is that it allows us to have all these bright minds working together and developing new or complementary technologies,” he says. “I see it as an idea generation facility, where we all think outside the triangle, because even the box is too traditional.

“We believe the cement industry will require a combination of technologies to truly reduce its carbon footprint,” says Mr. Harpur. “That’s why we have a range of cement-related technologies and intellectual property under development. PozGlass is one step toward doing things better. While it won’t replace 100 per cent of Portland cement, replacing even 50 per cent translates to a significant reduction in carbon emissions.”

All in all, it is “a great story when you can take a material that isn’t being fully utilized and turn it into something that can be of value to the environment and society as a whole,” Mr. Gue adds.

Advertising feature produced by Randall Anthony Communications. The Globe’s editorial department was not involved.