With concrete being the most widely used construction material in the world, organisations and businesses are looking to reduce the carbon dioxide emissions that are involved in the production by incorporating waste materials such as fly ash into concrete mixes.

According to Chatham House, a UK-based think tank, more than 4 billion tonnes of cement are produced each year, accounting for about 8% of global CO2 emissions.

Fly ash is becoming ever present as a suitable replacement for a portion of Portland cement used in most concrete mixes.

Substituting fly ash for 20-25% of Portland cement has been proven to enhance the strength, impermeability, and durability of the end product.

Using fly ash for this purpose as opposed to placing it in landfill or impoundments near coal power plants not only reduces waste management at sites, but also reduces CO2 emissions.

Rob McNally, Chief Growth Officer and executive vice president with Eco Materials Technologies, recently explained on ‘The Power Podcast’ that the ready-mix concrete industry has been reaping the benefits of using fly ash for years.

“It (fly ash) also has beneficial properties that typically makes it stronger long term and reduces permeability, which keeps water out of the concrete mixture and helps concrete to last longer. And, then, it’s also environmentally friendly, because they’re using what is a waste product as opposed to more Portland cement—and Portland cement is highly CO2 intensive. For every tonne of Portland cement produced, it’s almost a tonne of CO2 that’s introduced into the atmosphere. So, they have seen those benefits for years with the use of fresh fly ash,” McNally said.

With climate change concerns growing, many power plants are being pressured into retiring coal-fired power plants.

This results in a reduction in fresh fly ash. “The availability of fresh fly ash is declining,” said McNally. “In some places—many places actually—around the country, replacement rates that used to be 20% of Portland cement was replaced by fly ash are now down in single digits. But that’s a reflection of fly ash availability.”

Eco Material technology is one of the leading producers of sustainable cementitious materials in the U.S., with nine fly ash harvesting plants in operation or under development.

One recently announced project is at Georgia Power’s Plant Branch, a coal-fired station that retired in 2015. Under the agreement, Eco Material will harvest approximately 600,000 tons of landfilled ash per year from the plant in Putnam County, Georgia.

The effort is expected to remove and beneficially use more than 8 million tons of fly ash over a 15-year term. To find out more about this agreement, click here.

“There are billions—with a b—of tons of impounded fly ash around the country (America), so we have many, many years of supply,” McNally said.

Eco Materials is look towards the future, with a focus on green cement products using natural pozzolans such as volcanic ash to replace Portland cement in concrete mixes.

To listen to the full interview with McNally, listen to The Power Podcast.