Sometime in 2023, part of the California Department of Transportation (Caltrans) HOV 50 lane repair and resurfacing project in Sacramento needed to be fixed.
Flatiron Dragados West, the design-build contractor for the $511 million project, which started in 2021 along U.S. Highway 50 in the state capital, had to demolish and rebuild parts of a concrete viaduct along the route after learning the concrete failed to reach its design strength.
Last year, the contractor filed a $21 million breach of contract lawsuit in state court against the supplier, Sacramento-based Elite Ready Mix, but the terms of a November settlement were not disclosed.
Neither company could immediately be reached for comment.
A Caltrans spokesman said that “areas of the expressway with defective concrete have been fixed” and that the project is scheduled to be completed this summer. Flatiron Dragados, he added, has faced numerous complications, including long excusable weather-related delays and remains below the 2,000 days expected for completion required by its contract.
What happened to those particular shipments, however, is described in part in the lawsuit and other public records first revealed by the Sacramento news channel Abridged in December.
According to Flatiron’s January 2025 lawsuit complaint, the ordered concrete mix was to achieve a compressive strength of 6,000 psi and was to be used in the stems and soffits of a viaduct frame on Elmhurst Street. Caltrans has strict requirements related to material strength.
Faced with supply chain difficulties in obtaining Class F fly ash for the mix, Elite Ready Mix decided to substitute Class N natural pozzolana at its Bradshaw, Calif., plant without obtaining prior approval from Flatiron or Caltrans, Flatiron’s lawsuit stated.
According to court documents, Elite Ready Mix faced supply chain difficulties in obtaining Class F fly ash and made the substitution.
The supplier initially responded to Flatiron’s lawsuit in general terms, alleging that it had complied with the standard of care and industry standards, and all regulations and laws related to the use and delivery of cement materials on Caltrans projects.
Class F fly ash is a byproduct of coal combustion that acts as a natural pozzolanic material, reacting with cement hydration products to improve strength and durability in highway structures. Class N natural pozzolan performs a similar function, but differs in chemical reactivity, particle characteristics and speed of force development. Different ratios and tests are often needed to meet exact project specifications.
But in a breach-of-implied-warranty cross-complaint filed by Elite Ready Mix against its pozzolan supplier, Golden State Pozzolan, the concrete supplier explains its thinking in more detail. It argues that Flatiron’s design-build contract with Caltrans limited the amount of Portland cement that could be used in the project’s concrete and required that it be replaced with cement materials that appeared on a list of approved materials and the agency’s designated suppliers.
Elite: Materials never tested
Although only these materials were to be used, Elite Ready Mix argued that Caltrans never tested them “to consistently provide the necessary reactivity” needed for adequate cure, strength and durability.
In a letter related to another project and cited on the Abridged website, an Elite Ready Mix official explained that the use of natural pozzolana was necessary in this project. “to guarantee a stable and reliable product, without negatively affecting our customers’ schedules” and this [natural pozzolan sources] “they are so close that they are often the most reliable at times of the worst supply chain problems.”
Elite Ready Mix framed the switch as necessary “to ensure a stable and reliable product, without negatively impacting our customers’ schedules,” according to Abridged’s account of the letter.
The 28-day compressive strength test revealed the problem, Flatiron said. In July 2023, the contractor began demolition and replacement of the bridge components.
Neither Flatiron nor Elite Ready Mix have publicly commented on the resolution.
A lawyer for Golden State Pozzolan said his “customer strongly disputes the allegations made by Elite Ready-Mix in its cross-complaint” and “Our client’s response and evidence will be fully presented in the court records and proceedings.”
The fly ash shortage has occurred as a result of the accelerated shutdown of coal-fired power plants combined with fragile long-haul logistics, conditions that Elite Ready Mix cited for making the replacement.
The supply of fly ash is now stable, according to industry analysts IMARC Group and ChemAnalyst, and substitute materials that achieve high performance, including natural pozzolana, remain available.
