A major milestone has been reached on Colorado’s tallest dam. Construction materials company Amrize recently completed the cement supply for the roller-compacted concrete (RCC) used for the Gross Reservoir Dam Expansion Project in Boulder County – expected to become the world’s largest concrete dam raise using RCC once completed.
The project, which increased the dam’s height by 131 feet to 471 feet, will triple reservoir storage capacity from 42,000 acre-feet to 119,000 acre-feet once fully completed. The RCC phase transformed the structure from a conventional concrete gravity dam into a concrete arch dam — a first-of-its-kind application in the region.
Amrize recently supplied 75,000 tons of Made-in-America OneCem Portland limestone cement to the Kiewit-Barnard Joint Venture, the project’s general contractor, for this landmark infrastructure undertaking. Manufactured at the Amrize Portland, Colorado cement facility, OneCem was used to produce approximately 740,000 cubic yards of RCC and more than 68,000 cubic yards of foundation concrete, making it one of the largest recent RCC placements in North America.
“This project required exceptional performance, consistency and reliability at a tremendous scale,” said Patrick Cleary, SVP, US cement & supply chain, Amrize. “OneCem provided the characteristics needed for roller-compacted concrete construction, while our local team leveraged Amrize‘s statewide terminal network to ensure uninterrupted material supply despite the site’s remote mountain location.”
Final project activities, including spillway construction and reservoir preparation, are expected to continue through 2027 and strengthen water security for millions of residents across Colorado’s Front Range, one of the fastest-growing regions in the United States.
