The imperative to reduce carbon emissions in the built environment is central to the Architecture 2030 Challenge.

Public and private sector research labs worldwide are racing to deliver carbon-reducing building materials. Chief among them: zero-carbon concrete.

Material scientists have made dramatic strides in recent years reimagining concrete composition and formulation. Commonly available manufacturing byproducts such as fly ash, bottom ash, slag, and other pozzolans are viable carbon emission-reducing replacements for traditional cement clinker.

A new $14.2 million, 14,508-square-foot net-zero public facility near Watertown, Conn. proves that. The project team from TLB Architecture specified locally available glass pozzolans as a partial clinker replacement. Glass pozzolans cut global warming potential by 95% compared to traditional Portland cement, reports Michael Fortuna, AIA, project lead and TLB Architecture principal.

Beyond Carbon Offsets

ARCHITECT editor-in-chief Paul Makovsky recently profiled the work of Skidmore, Owings & Merrill and their partners in creating sustainable concrete. The global design giant is helping pioneer a bio-concrete alternative to traditional concrete using nontoxic blue-green algae. Makovsky writes that photosynthesis is used to help “… create a material similar to the calcium carbonate generated in coral reefs and oyster shells.”

Safety certification of the bio-concrete by ASTM International is well underway, as is a new manufacturing plant. As SOM’s managing partner, Brant Coletta, AIA, told ARCHITECT, “Carbon offsets are no longer enough. The future needs to be carbon negative. This material enables us to do that immediately without fundamentally changing the way buildings are designed.”

Carbon Negative Breakthrough

Coletta’s decarbonization call to arms has been heard loud and clear in Oregon. There, a group of material science innovators have come up with a way to sequester carbon in concrete using organic waste products. “The opportunity to sequester meaningful levels of carbon in concrete is significant,” observes Lionel Lemay, executive vice president of structures and sustainability for the National Ready Mix Concrete Association, a leading voice in the built environment’s transformation to a carbon-free future.

The Oregon initiative uses an admixture made from biosolids, a waste stream from municipal wastewater treatment plants. The use of biosolids simultaneously solves an expensive waste management headache while creating a possible revenue opportunity for communities. Ordinarily, biosolids are left in a landfill to decompose, which generates CO2 and methane. Methane is a greenhouse gas 80 times more destructive to the environment than CO2.

Commercial Application

The biosolid waste is transformed into a sequestered carbon product. The Oregon team then supercharged carbon reduction with a new type of sustainable cement called OneCem. OneCem uses less clinker than the traditional manufacturing process and reduces CO2 emissions by five to 10% per ton of cement.

The one-two punch of a biosolid admixture combined with OneCem delivers an impressive global warming potential of just 90 kilograms of CO2 per cubic yard of concrete (versus about 181.4 kilograms of CO2 per cubic yard for traditional concrete). Now factor-in the GWP reduction of methane landfill emissions over a 20-year period. The result is carbon-negative concrete.

The Remy Wines in McMinnville, Ore. is believed to be the first commercial application of this net-negative concrete formulation. Watch for the Remy Wines story in coming weeks.

Learn more about how next generation concrete is helping meet sustainability goals with “The Top 10 Ways to Reduce Concrete’s Carbon Footprint.”