6 Ways Concrete Can Cut Carbon Emissions

Created By RISC | 2 years ago

Last modified date : 2 years ago

Concrete is commonly used in buildings and structures yet is a significant source of carbon dioxide (CO₂).​

Concrete’s many benefits include strength, versatility, affordability. But it emits a lot of CO₂, accounting for 6-10% of global emissions. Portland cement is the largest source of carbon emissions.​

So how can we lower our carbon footprint while using concrete in construction?​

Burning fossil fuels to make concrete contributes to about 40% of the carbon dioxide from its production. The other 60% comes from chemical reactions during concrete mixing. The carbon footprint of concrete varies with its components. Using less cement is the most effective way to reduce its carbon footprint.​

Let's look at 6 practical ways that concrete can reduce carbon emissions and environmental impact.​

• Using coal fly ash instead of Portland cement can create low-carbon concrete. Using less cement equals less carbon. Greenhouse gas emissions can be decreased by at least 17 kg/m³ (relative to normal concrete of equivalent strength).​

• Carbon sequestration (CO₂ injection) captures emitted carbon during the cement manufacturing process and injects it back into the concrete during the mixing phase. The carbon dioxide reacts with the cement's calcium ions to create calcium carbonate.​

• Spacing out structural supports can help reduce carbon emissions.​
- Buildings can be designed to need fewer massive beams and thinner floor slabs. But the proper column distance must also be considered to minimize the overall use of concrete.​
- A structure with a span of long columns can maximize space while using fewer columns and foundations. But HSC with a higher cement proportion may be required to reduce the thickness of columns and floors. Structural design can have an impact on the embodied carbon in a structure. Correct design and a holistic understanding of overall concrete usage are essential for carbon reduction.​

• Depending on the application, post-tensioning or pre-casting may be used. To obtain the requisite early strength, the post-tension structure or casting in place requires a higher cement content. Thinner concrete and less cement are used in pre-cast floor and wall structures, resulting in less overall embodied carbon for the same amount of space (depending on the overall design of the structure)​.

• Using lightweight materials, such as lightweight concrete, helps reduce overall carbon because when the building's floor and walls are lightweight, the load on the columns and foundations is reduced, resulting in a smaller structure and less concrete.​

• Concrete can be recycled from building leftovers such as pile head waste. It can also be crushed, processed, and reused with iron aggregate and cement for subgrade roads.​

References:​
https://materialspalette.org/concrete/