At Washington State University, a viable formulation of carbon-negative, environmentally friendly concrete has been developed that has nearly the same strength as regular concrete.
In proof-of-concept work, the researchers infused ordinary cement with eco-friendly biochar, a type of charcoal made from organic waste, pre-enhanced with concrete wastewater. Biochar was able to absorb up to 23% of its weight in carbon dioxide from the air while reaching strengths comparable to regular cement.
This research has the potential to significantly reduce the carbon emissions of the concrete industry, one of the most energy and carbon intensive industries of all manufacturing. The research, led by PhD student Zhipeng Li, is reported in the journal Materials Letters.
Xianming Shi, professor of civil and environmental engineering at WSU and corresponding author of the paper, said:
More than 4 billion tons of concrete are produced worldwide each year. High temperatures and fuel combustion are required to make ordinary cement. Cement production is believed to account for about 8% of the world’s total carbon emissions from human activities, as the limestone used in production also decomposes to produce carbon dioxide.
Researchers have tried to add biochar as an alternative to cement to be more environmentally friendly and reduce carbon footprint, but even a 3% addition of biochar dramatically increases the strength of the concrete. decreased to After treating the biochar in concrete washing wastewater, WSU researchers were able to add up to 30% biochar to the cement mix. Pastes made with biochar-modified cement were able to reach a compressive strength after 28 days comparable to that of regular cement of approximately 4,000 pounds per square inch.
“We are working to find new ways to repurpose waste streams into beneficial uses for concrete. “The trick really lies in interface engineering: how you design the interface of the concrete.”
Wash water for caustic concrete can be a problem as a waste product from concrete manufacturing. Wastewater is highly alkaline, but it also serves as a valuable source of calcium, he says. Researchers used calcium to induce the formation of calcite. This benefits biochar and ultimately biochar-incorporated concrete.
“Most other researchers were only able to add up to 3% biochar instead of cement, but now that we have found a way to manipulate the surface of the biochar, we have demonstrated the use of much higher doses of biochar. I do,” he said.
The synergistic effect of highly alkaline wastewater with high calcium content and highly porous biochar allows calcium carbonate to precipitate on or in the biochar, strengthening it and capturing carbon dioxide from the air. Now Concrete made from this material is expected to continue to sequester carbon dioxide for the life of the concrete, typically 30 years for pavements and 75 years for bridges.
To commercialize the technology, the researchers worked with the Office of Commercialization to protect intellectual property and file a provisional patent application for carbon negative concrete work. They recently received a seed grant from the Washington Research Foundation to generate more data for a variety of use cases. He is also actively seeking industry partners in the building and construction sector to scale up production and license this his WSU technology for field demonstrations.
Original: Researchers develop carbon-negative concrete
Than: Washington State University
