Moving towards a carbon neutral future

Cement, as a material, currently contributes approx. 8% of global CO2 emissions - are we on the cusp of solving this huge problem?

Carbon-negative concrete is an innovative area in sustainable construction, aimed at reducing and eventually reversing the carbon footprint of concrete, a material traditionally associated with significant carbon emissions due to its production process, especially in cement manufacturing.

Some critical advancements in carbon-negative concrete include:

1. Carbon Capture and Utilization (CCU) in Concrete Production

CarbonCure Technologies: This technology injects captured CO? into fresh concrete during mixing. The CO? reacts with calcium ions from cement to form calcium carbonate, which becomes permanently embedded in the concrete, reducing its overall carbon footprint.

Blue Planet: This approach uses CO? to create synthetic limestone aggregates, which can replace conventional aggregates in concrete, turning the material carbon-negative by storing more carbon than is emitted in its production.

2. Bio-Based Concrete

Algae-based Concrete: Researchers are exploring the potential of algae to capture CO? during its growth, which can then be incorporated into concrete. This bio-concrete uses the photosynthetic process of algae to absorb CO?, providing a net negative impact over its lifecycle.

Biomass as Alternative Aggregates: Some approaches involve replacing traditional aggregates with carbon-sequestering materials, such as biochar, a byproduct of burning organic waste. This locks away carbon in the concrete for extended periods.

3. Alternative Cement Formulations

Geopolymer Cement: Unlike traditional Portland cement, geopolymers use industrial byproducts like fly ash or slag, which do not require the energy-intensive calcination process that produces large amounts of CO?. When combined with CCU methods, these materials reduce emissions and can contribute to carbon-negative outcomes.

Magnesium Silicate Cement: Some new cements are based on magnesium silicate, which absorbs CO? as it hardens, offering a significant reduction in emissions compared to traditional cement.

4. Concrete That Absorbs CO? Over Time

Reactive Concrete: Certain types of concrete can be engineered to absorb atmospheric CO? as they age, turning the concrete itself into a carbon sink over its lifetime. This approach helps reduce the net carbon emissions of structures built with such materials.

5. Energy-Efficient Production Processes

Low-temperature Cement: Research is underway into producing cement at lower temperatures, which can reduce the CO? emissions associated with the energy consumption in traditional cement production.

Direct Air Capture Integration: Some companies are exploring integrating direct air capture (DAC) technologies with cement plants, allowing the captured carbon to be used directly in production, further reducing emissions.

These innovations are critical to addressing the construction industry’s contribution to climate change and are part of a broader movement toward decarbonizing infrastructure projects.