Sustainable concrete reduces carbon emissions by at least 30%

Months ago we heard news of the “nation’s first carbon-positive hotel”—a 13-floor, 130-000-sf cement tower with a triangular layout and eye-shaped windows. Populus, designed by Studio Gang and developed by Urban Villages, broke ground in Denver, Colo., last year with plans to be operational by summer 2024. What makes Populus a carbon-positive project is a collection of variables, from minimizing waste to using fewer finish materials. But there’s one huge driver behind the green initiative: sustainable concrete.

ECOPact is an optimized, low-carbon concrete made from large amounts of supplementary cementitious materials (SCM). With lower embodied carbon content compared to conventional concrete, ECOPact aims to be an attractive alternative for sustainability-driven engineers.

Sustainable concrete: ECOPact

Designed by Holcim, a sustainable building materials supplier, ECOPact offers a low-carbon alternative that not only meets, but exceeds the properties of standard (CEM I) concrete. This allows the material to be used in all traditional applications: structural components like foundations, columns and beams; to walls, driveways, bridges, and more.

ECOPact Tiers

Rather than having a one-size-fits-all product, Holcim delivers ECOPact in a three-tiered system:

• ECOPact (30–50% reduction in carbon emissions)
• ECOPact Prime (50–70% reduction)
• ECOPACT Max (70–90% reduction)

Each tier can be enhanced with the addition of recycled concrete aggregates ECOPact+ range, according to the company. Kevin Peart, Senior Vice President and General Manager of the Mountain Region, Holcim, believes that Holcim has become “one of the first movers in the concrete industry.”

For the Populus hotel, this sustainable concrete was integral to the design process. The project’s utilization of ECOPact accounts for 65% of the total cubic yards of concrete poured, with an anticipated reduction of 765 tons in the concrete's embodied carbon compared to traditional concrete.

A similar story is told at 55 H Street, a Georgetown University residence hall (above). The project team had a specific challenge: they needed a concrete blend capable of attaining a 28-day design strength of 5,000 psi, while also achieving a high-early strength of 3,000 psi within a span of two to three days. ECOPact delivered, and 55 H Street became “one of the most sustainable buildings in D.C.,” says Zachary Lovett, Project Pursuit Manager, Holcim.

As the built environment continues to find ways to reduce its impact on the planet, innovative materials like ECOPact may help drive the change that architects, engineers, and contractors desire.