Sydney-based cleantech company alterBiota has announced its flagship concrete additive, deltaC, has graduated from the R&D phase to commercial production as construction industries seek lower-carbon materials.

DeltaC is a liquid admixture made with biochar, a carbon-rich material produced from forestry byproducts. According to alterBiota, the additive can reduce the carbon footprint of concrete by up to 30 percent while also improving how concrete mixes and hardens.

Concrete producers commonly use admixtures to modify strength and workability, but deltaC is designed to store carbon as well, allowing for emissions reductions without necessarily cutting the amount of cement used.

"After nearly five years of intense R&D, it is deeply rewarding to introduce our deltaC product to the concrete market." said alterBiota CEO and Co-Founder Mark Masotti in a statement. "With customers like CarbonRun, producer partners like Casey Concrete, and a world class innovation ecosystem in Nova Scotia, we have been able to successfully demonstrate a practical, scalable, renewable, and cost-effective way to achieve net new decarbonization of concrete."

The company – which raised $4 million in 2024 in an equity round led by Invest Nova Scotia – tested its commercialization efforts this summer, supplying more than 100 cubic metres of concrete for projects such as sidewalks, curbs, and structural pads. AlterBiota reported that these projects achieved carbon-reduction levels ranging from 10 to 22 percent, depending on whether the producers also reduced cement content.

One of the largest demonstrations took place in collaboration with CarbonRun, the Dartmouth-based company that deploys river-restoration technology. Casey Concrete of Truro supplied deltaC-enhanced concrete for the foundation of a limestone-storage silo in a remote location. The concrete mix was required to reach a strength of 35 megapascals in 28 days, but alterBiota says the mix surpassed that target after only three days.

The higher early-stage strength allowed installation of the silo ahead of schedule and lowered the foundation’s embodied carbon by 22 percent through a combination of cement reduction and carbon storage in the biochar.

Casey Concrete reported that the admixture integrated easily with its existing production process and produced concrete with consistent handling and finishing characteristics. CarbonRun added that the accelerated strength development helped speed the project while meeting its environmental goals.

AlterBiota described deltaC as a cost-saving alternative to materials such as silica fume and as an option that avoids supply-chain challenges associated with fly ash and steel slag, which are becoming scarcer as coal-fired power generation and blast-furnace steelmaking decline. The company also highlights the product’s reliance on forestry byproducts, which were previously absorbed by a now-reduced pulp-and-paper sector.

"The performance improvements we saw with deltaC were impressive,” said CarbonRun Co-Founder and CTO Eddie Halfyard. “Achieving our required strength in a fraction of the expected time helped accelerate field deployment while reducing the embodied carbon of the project.”