The mechanism
A concrete or cement escalation clause ties the cement-related part of a contract price to a published index instead of fixing it at signing. The standard benchmark for ready-mix supply is the BLS Producer Price Index for Ready-Mix Concrete Manufacturing, series PCU327320327320. This series prices the batched output (cement, aggregate, water, admixtures, and delivery combined), not cement alone. Cement itself is a separate NAICS category (327310) with its own PPI; if the contract is specifically for cement rather than delivered ready-mix, confirm the current cement-specific code at bls.gov/ppi rather than reusing the ready-mix series.
Construction is the textbook example most escalation-clause explainers open with, yet it's one of the bigger gaps in most materials-clause coverage, which tends to favour steel and lumber instead. Cement, the biggest single cost driver inside the ready-mix figure, moves with kiln energy costs and regional plant capacity, and ready-mix supply contracts routinely run long enough that a fixed bid price becomes unworkable if that input moves hard mid-project.
The calculation, step by step
- Base index value. The index value at the base period, usually the month of contract signing or bid submission.
- Current index value. The index value at the adjustment date, usually the month of delivery or invoicing.
- Ratio. Current value divided by base value.
- Adjustment. The ratio applied to the concrete- and cement-affected portion of the contract price, not necessarily the whole contract.
A clause with a $400,000 cement-affected scope, a base index of 310.0, and a current index of 341.0 produces a ratio of 1.10: a 10% increase, or $40,000 added to that scope.
Where clauses go wrong
- No series code. "The cement index" is not a series. BLS publishes distinct series for cement manufacturing, ready-mix concrete, and specific precast products, and they price different things. Name the exact code, for example PCU327320327320 for ready-mix, so there is nothing to argue about later.
- No averaging window. A single month's index value is more volatile than a 3-month rolling average. Clauses should state which is used.
- Publication lag ignored. BLS data publishes with a lag, and early releases can be revised. Clauses should state whether the final or preliminary value applies.
- Double-counting energy. Cement is energy-intensive, so a clause that indexes both a cement PPI and a separate energy series (natural gas for the kiln, for example) can price the same underlying cost driver twice if the two components aren't scoped to different parts of the contract.
- No cap or floor. Without a cap, an index spike passes through in full, which can make the clause commercially unworkable in a large swing.
Related
- Free escalation clause analyzer: paste a clause and see the formula, undefined terms, and risk score.