Thanks to Webcor Concrete Director Eric Peterson's depth of knowledge and recent opportunities, Webcor is at the forefront of the effort to reduce the levels of embodied carbon in concrete.

The Webcor Concrete director invests considerable time working to influence the approaches the industry is taking based on his research, project experience, and work he does on various material and specification committees. Eric was recently asked to speak at two events, one as a speaker and the other as a panelist. In the last couple of months, he was a panelist at the Massachusetts Low Carbon Concrete Roundtable and a speaker at the American Concrete Institute Foundation's Technology forum sponsored by the Concrete Innovation Council.

"Clients are driving this," Eric says. "It's not the government or the concrete industry. It's clients who say they want to be environmentally conscious. They have well-educated specialists in sustainability  to ensure that the projects they undertake have low embodied carbon.” He cites Google, Facebook, and Contra Costa County as examples of recent Webcor clients seeking builders with sustainability expertise. "Mostly, they come to us while they're developing the project scope."

The bottom line, Eric says, is that if you want to win projects, you'd better know how to work with low embodied concrete – concrete mixes with a low global warming potential (GWP).

An Alphabet Soup of Organizations

Part of his work involves interacting with organizations that have made lower-carbon concrete a priority. The National Ready Mixed Concrete Association is among them; the NRMCA has made a lot of data available that shows how much carbon is being used in typical mixes. The Carbon Leadership Forum (CLF) has established a materials baseline report, which details the amount of embodied carbon in all construction materials, including concrete mix designs based on strength classes. And a new organization, the Center of Excellence for Carbon Neutral Concrete, part of the American Concrete Institute Foundation (Neu), is adding to the growing momentum. The International Organization for Standardization (ISO) writes the standards which function as the rules for evaluating the GWP of building materials to produce what is known as an environmental product declaration (EPD).  The Portland Cement Association (PCA) has released a report titled “The Roadmap to Carbon Neutrality.”

When the organizations of the International Union of Laboratories and Experts in Construction Materials, Systems, and Structures (RILEM) and the American Concrete Institute (ACI) ) held a jointly sponsored event in Paris last year -- the 11th International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete -- Eric was up every morning at 4 a.m. to listen as participants presented their papers, which ultimately totaled 770 pages. "The amount of research going into this is astounding," he says. "People are working worldwide to figure out how to do this.

"We're starting to see goals for embodied carbon in specifications for both normal and light-weight concrete of all strength classes," Eric says. "Clients want to see the total embodied carbon for the job. We need to be able to determine what the GWP will be for the entire job so we can meet or exceed project objectives." That's a challenge, he says, because the approach now is based on specific project elements. In some cases, embodied concrete in project phases is specified. In others, the maximum mass of Portland mix in any given mix is specified for mix classes, such as shear walls, foundations, and elevated slabs. "For example, for a shear wall at 10,000 psi, a recent project specified a maximum of  250 pounds of Portland Cement as opposed to the 600 pounds which would normally be used."

Rethinking the Infrastructure

Most efforts to reduce carbon in concrete start with replacing Portland Cement, the most common type of cement in general use around the world, with what are called “supplementary cementitious materials” (SCM). Nearly all SCMs are produced from waste products of other industries, such as power and steel production.  "But why use pure cement at all?" Eric wonders. "We should start with a blended cement, and specifiers should specify these. If the basic cement being distributed to batching facilities starts off with, for example, a 20 percent replacement of ground-granulated blast-furnace slag, we could continue to improve this value but have an initial starting point that already has a 20 percent reduction of Portland Cement use.  If all concrete in a given region started with a blended cement product, this would reduce the national usage of Portland Cement overnight."

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Making that transition is an enormous undertaking that could be alleviated if governments provided incentives or funding to facilitate industries’ ability to expand the availability of low-carbon mixes. "We lack industry-wide coordination. Many organizations and governmental bodies have goals and dates on which carbon neutrality needs to occur, but nobody's providing a detailed schedule of steps to take to get where we need to be. The industry needs some specific guidance. That could come from the federal government, local government, and industry associations, but right now, it's fragmented. This, along with strategic government funding to facilitate infrastructure and resource improvements, are the biggest items missing," according to Eric. "Without that, we're swinging in the blind."

Another issue, Eric says, is that optimizing mixes can only take the industry so far. To look beyond that limited solution, Eric has been paying attention to other solutions.  One of them is Brimstone Energy, which has a patent for making cement using silicious rather than carbonate rocks. (Silica is the primary constituent of silicious rocks, while carbonate rocks are composed primarily of carbonate minerals.) "They're in the process of developing a demonstration plant in Nevada," says Eric, who has been introducing company leaders to others in the industry who can help advance this solution.

What Webcor's Doing

Within Webcor, Eric participates in a meeting held every three weeks headed by Webcor’s Sustainability Director, Sarah Rege, and Specialist Allyson Chavira.  It also includes Concrete Superintendent Daniel Rinaldi, Project Director Mark Bettencourt, Sr. Superintendent Alan Blevins, and Eric. "It is an active effort to stay up to date. We're collecting data on mixes, modifying concrete logs to track strengths, and better understand what we're achieving and what we can improve," Eric says.

"Even if you don't believe in climate change, there are now four times the number of people in the world than there were when I was born. We need to learn to do more with less. The harder we work while maintaining profitability and marketability, the better we'll be. We'll conserve resources and be more efficient with what we have. I believe in this on a philosophical level and find it fascinating on a technical level," Eric explains.

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