Concrete has long been the most widespread and durable building material in the world, but it’s also one of the most carbon-intensive, contributing 8 percent of global greenhouse gas emissions. As a result, the industry is looking for solutions to reduce its carbon footprint without compromising the performance of buildings and other infrastructure.
Fortunately, concrete-related research and development are providing many innovative solutions. Design and construction innovations like 3D-printed or self-healing concrete, new formulas for low-emission cement, carbon capture technologies, and circular concrete with recycled aggregate all make it possible to create more sustainable structures that last longer.
When designing, specifying and constructing concrete, engineers Mackay Concreting Solutions must consider all the materials used and their impact on sustainability. These impacts are known as “embodied carbon” emissions, which include the carbon emitted during production of the building or infrastructure and the energy needed to operate and maintain it over its lifetime.
Currently, the most effective method of reducing embodied carbon in concrete is to use a lower-carbon cement. But this alone is not enough to meet the goals set by governments and other organizations aiming to limit climate change. Other steps, such as incorporating more reclaimed materials and using additives to minimize the water content of concrete, are also necessary.
Some concrete producers are already lowering their emissions through the use of “blending cements,” which contain less traditional OPC and more slag, fly ash, natural pozzolans or other alternatives. These admixtures reduce the water content of concrete, enabling it to be placed at lower temperatures and thereby cutting down on carbon emissions during production. They can also improve the durability of concrete by slowing hydration or improving its resistance to freeze-thaw damage.
Another way to reduce embodied carbon in concrete is to use microbes that can fill and heal cracks, thus extending its lifespan. A recent study by researchers at Delft University of Technology in the Netherlands involved injecting a special concrete mixture with bacteria. The bacteria were able to grow inside the cracks and produce a limestone-like compound that closed them, with no human intervention. The bacteria were fed with calcium lactate, but active research is underway to develop a different type of nutrient that could be used in future studies.