Carbon-Neutral Concrete Products
Researchers and Concrete Companies Have Found Ways to Reduce the Amount of Carbon Dioxide Emitted with Concrete Products
Concrete products are responsible for an estimated five percent of carbon dioxide (CO2) emissions annually. And that amount will only increase as the world’s population grows. But researchers and concrete companies alike are dedicated to producing concrete products that are carbon-neutral. This is especially true in expanding countries where concrete construction is booming, such as in China.
Concrete companies can reduce their environmental footprints by using concrete products that are carbon-neutral. Here’s how these products work to reduce CO2 emissions.
Replace Portland Cement
Traditional concrete production relies on the use of Portland cement, which is responsible for a large amount of CO2 emissions in the concrete industry. However, two Canadian concrete companies have found ways to inject CO2 into the binding process during concrete production, replacing the need for Portland cement.
One company injects the CO2 into the wet concrete during the mixing process to create carbonate ions that turn into calcium carbonate minerals. In other words, the reaction of the CO2 mixed into the concrete creates limestone. This not only improves the strength of the concrete, but it also reduces the amount of Portland cement needed for ready mixed materials by five to eight percent.
Recycle Industrial Waste
One of these concrete companies uses slag from steel factories to replace the Portland cement. Slag is industrial waste, consisting of calcium, oxides, hydroxide, silicates, and other materials. The slag reacts with the CO2 during the concrete curing process. As a result, these materials become hard and bind together. This company can create various concrete products using the slag-CO2 mix and different molds, such as:
- Highway dividers;
- Paving stones; and,
- Sewer pipes.
Carbon-neutral companies aren’t just reducing their carbon footprints for concrete production by reducing or eliminating the need for Portland cement. They’re also sequestering CO2 by injecting it into the concrete, trapping it, and making better use of it without the CO2 being free in the atmosphere. Companies that specialize in carbon capture supply this CO2 for concrete production.
For each 18-kilogram cinderblock produced using the carbon-neutral process, they are able to offset and sequester the amount of CO2 emissions created in the production of three kilograms of Portland cement.
The use of industrial waste (slag) to replace Portland cement is both affordable and sustainable. Instead of this waste ending up in landfills, it is being used to reduce carbon emissions in the concrete production process. And by sequestering CO2 to create a strong concrete that relies less on cement, this CO2 will serve a better purpose on the ground instead of in the air.