Brief
Discover how Washington State University engineers have developed an innovative carbon-negative concrete using treated biochar, a breakthrough with the potential to transform the construction industry and reduce CO2 emissions.
Insight
Engineers at Washington State University (WSU) have developed a carbon-negative concrete using biochar, a charcoal derived from organic waste. This innovative method could significantly reduce the cement industry’s carbon footprint, which currently contributes to 8% of global carbon dioxide emissions.
Scientists have previously attempted to decrease concrete’s environmental impact by altering its composition, using alternatives like volcanic rock, titanium dioxide, construction waste, baking soda, clay, or even microalgae. The WSU researchers focused on incorporating treated biochar to create a more sustainable concrete.
Biochar has been previously mixed with cement, but the WSU team enhanced its strength by treating it with concrete washout wastewater. This allowed for a higher proportion of biochar in the mixture, which could absorb up to 23% of its weight in carbon dioxide from the surrounding air.
The researchers produced cement containing 30% treated biochar and found the resulting concrete to be carbon-negative. The 30%-biochar concrete removed approximately 13g more CO2 than its production emitted per 1kg of material. This is a significant improvement compared to regular concrete, which releases around 0.9kg of CO2 per 1kg of material.
The team also suggests that the overall gains could be even greater when considering downstream differences. Using biochar in concrete diverts biomass from other environmentally detrimental fates, while the new concrete continues to absorb CO2 throughout its several-decade-long lifespan.
Importantly, the biochar-concrete maintains its strength, with a compressive strength of 27.6 MPa after 28 days, similar to regular concrete. The researchers plan to further optimise and scale up the method, as well as test the concrete’s resistance to weathering and other types of damage.
This breakthrough in carbon-negative concrete has the potential to revolutionise the construction industry by significantly reducing CO2 emissions and contributing to a more sustainable future.
Highlight
- Biochar could absorb up to 23% of its weight in carbon dioxide from the surrounding air.
- The researchers produced cement containing 30% treated biochar and found the resulting concrete to be carbon-negative.
- The 30%-biochar concrete removed approximately 13g more CO2 than its production emitted per 1kg of material.
- Importantly, the biochar-concrete maintains its strength, with a compressive strength of 27.6 MPa after 28 days, similar to regular concrete.
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