It’s All in the Mix
Aggregate Industries developed a concrete mix design that actually helps the environment.
Ready-mix producers aren’t just looking for ways to make their operations more “green” or environmentally friendly, they want to find ways to extend sustainability into their finished products and into the community around them. Aggregate Industries is making that happen through research and development initiatives with the National Ready-Mix Concrete Association (NRMCA) and the Massachusetts Institute of Technology.
Through those initiatives, Aggregate Industries is helping develop new techniques and technologies that are improving how concrete interacts with its surrounding environment. “We have developed a series of environmentally friendly concrete mix designs that we call the Emerald Series,” says Joel Nickel, environmental and land services manager for Aggregate Industries. “The Emerald Series consists of environmentally friendly products that we can deliver not only internally to our plants, but also externally to our customers.”
Nickel says his company focuses on what he calls the triple bottom line — economic performance, environmental performance, and corporate social responsibility. “We try to preach those aspects to the businesses wherever we operate,” he says, “everywhere from the ready-mix plants and asphalt plants to the quarries and sand and gravel operations.”
One of the products in the Emerald Series is called SCM, which stands for supplementary cementitious materials. SCM uses recycled products to make concrete and minimizes the use of fly ash in the mix designs.
The second product is pervious concrete, which has the company excited about the possibilities. Pervious concrete is used in parking lots, driveways, sidewalks, and golf cart paths, but it can also be used for slope protection for unstable ground.
“We typically use pervious concrete to improve storm water runoff, reduce water retention requirements on site, and increase site sustainability and suitability,” Nickel says. “We started developing pervious concrete, first, for our own purposes. We install it at our own sites to put storm water controls in place at our operations throughout the United States.”
Through research and development initiatives with the NRMCA and MIT, Aggregate Industries is helping develop new techniques and technology that are improving how concrete interacts with its surrounding environment.
Once pervious concrete was being used extensively within the company, Aggregate Industries began having demonstrations at some of its plants and in areas such as Chicago and Milwaukee to highlight how the pervious concrete performs in wet weather conditions.
“We’re trying to educate not only our customers, but also governmental agencies on how certain mix designs and pervious concrete can benefit the environment they live in today,” Nickel adds. “Many governmental agencies are implementing storm water impact fees when new buildings are going up. We’re trying to educate the building design firms so they know that pervious concrete reduces that impact fee because it allows water to infiltrate into the ground rather than create runoff that goes into a storm water pond.”
Pervious concrete can also contribute to safety, Nickel says. After a heavy rainfall or snowstorm, it allows the precipitation to flow through the concrete and infiltrate the ground, so there are less likely to be puddles left to freeze up in cold weather that could cause slips and falls.
As chair of the Environmental Committee at the NRMCA, Nickel says that one of the things the organization is working on is trying to reuse and recycle more water in mix designs used for Department of Transportation (DOT) specifications. “Some states don’t allow recycled water content in DOT- or state-specified jobs,” he says, “but some states allow up to 23-percent recycled content water in the mix. What we’re trying to do, as an organization, is to find applications where the standards can support a certain percentage of recycled water that we can then use in our mix designs, thereby reducing the environmental impact. We’re summarizing for our members and other stakeholders what each state allows and what each state doesn’t allow in terms of recycled water content. That’s our first step. We’re hoping to have all that information available by the end of September or the beginning of October so we can move on to the next step of the initiative.”