Reducing carbon emissions by at least 30% using sustainable concrete

Several months ago, news emerged about the project called Populus, hailed as the "nation's first carbon-positive hotel." This 13-floor, 130,000-square-foot cement tower in New York City's Little Italy garnered attention for its triangular layout and eye-shaped windows. The construction began in Denver, Colorado, last year, with the aim to become operational by spring 2024.

The key factor setting Populus as a carbon-positive project is its commitment to sustainability, encompassing practices such as waste reduction and the use of fewer finishing materials. However, the driving force behind its eco-friendly initiative is sustainable concrete.

ECOPact, developed by Holcim, a leading supplier of sustainable building materials, is an optimized, low-carbon concrete enriched with significant amounts of supplementary cementitious materials (SCM). ECOPact boasts lower embodied carbon content compared to conventional concrete, making it an attractive choice for various applications.

Holcim has structured ECOPact into a three-tiered system: (i) ECOPact (30–50% reduction in carbon emissions), (ii) ECOPact Prime (50–70% reduction) and (iii) ECOPACT Max (70–90% reduction). These tiers can be further enhanced with the incorporation of recycled concrete aggregates from the ECOPact+ range. It is mentioned that as the built environment strives to minimize its impact on the planet, innovative materials emerge as potential catalysts for change, meeting the desires of architects, engineers, and contractors.

In the case of the Populus hotel, sustainable concrete played a crucial role in the design process. Approximately 65% of the total cubic yards of concrete used in the project consisted of ECOPact, resulting in an expected reduction of 765 tons in embodied carbon compared to traditional concrete. A similar success story unfolded at 55 H Street, a residence hall at Georgetown University. Faced with the challenge of requiring a concrete blend capable of achieving a 28-day design strength of 5,000 psi and a high-early strength of 3,000 psi within two to three days, the project team turned to ECOPact. The outcome was a sustainable building described as one of the most sustainable buildings in D.C.