HDOT Testing Sustainable Concrete Mix

The Hawai‘i Department of Transportation (HDOT) is conducting a test of a concrete mix injected with waste carbon dioxide as a sustainable transportation initiative. The test involves a pour of 150 cubic yards of carbon-injected concrete next to an equivalent pour of standard concrete mix on an access road for the Kapolei Interchange Phase 2.

This test will allow HDOT to do a side-by-side comparison of the two mixes to determine specifications for the use of carbon-injected concrete for road projects in the future.

“I am pleased to see HDOT moving ahead with CarbonCure, local concrete companies, and Hawai‘i Gas to reduce the levels of carbon dioxide emitted during the construction process,” said Gov. David Ige. “As the daily baseline measurement for carbon dioxide in our atmosphere reaches the highest level in modern history, it is especially important for all of us to do all we can towards ensuring a sustainable Hawai‘i for future generations.”

The carbon-injected concrete used in the testing is produced by Island Ready-Mix Concrete using waste carbon dioxide from Hawai‘i Gas. The carbon dioxide is mixed into the concrete using CarbonCure technology. The resulting product traps carbon dioxide in mineral form within the concrete and improves the comprehensive strength of the material. This project is supported by Elemental Excelerator—a Hawai‘i-based startup accelerator that has supported more than 50 projects alongside startups, local businesses, and government agencies.

“We are proud that Hawai‘i is looking at sustainable building practices to mitigate the effects of climate change,” said Aki Marceau, managing director for the Elemental Excelerator.

Depending on the final specifications, the use of carbon-injected concrete could reduce embodied carbon by 25 pounds per cubic yard. A mile of concrete pavement uses roughly 21,000 cubic yards of concrete. The amount of concrete poured in the HDOT demonstration project will save 1,500 pounds of carbon dioxide, offsetting the carbon dioxide emissions from 1,600 miles of highway driving.

Concrete is the most abundant manmade material on earth and is responsible for seven-percent of global manmade greenhouse emissions, making it the world’s second largest industrial source of carbon dioxide, according to the International Energy Agency.