THE FLY ASH SUPPLY.
WHAT CHANGED,
AND WHERE IT STANDS.
23 coal-fired units at 15 plants stopped burning coal in 2025 alone (EIA). Fly ash used in concrete rose in 2024. Then two utilities moved to keep coal plants running past planned retirement dates.
What changed, by date.
When generation changes in a region, what a local plant can source changes with it, and the finished concrete does not show which version it got. Without a record, a dispute years out is one party's memory against another's.
Supply shrank. Demand grew.
2.6 GW of coal capacity retired in 2025, per EIA.
Fly ash used in concrete rose from 11.9 million tons in 2023 to 14.6 million tons in 2024 (American Coal Ash Association, 2024 Production and Use Survey, released 4 December 2025).
The pattern is not yet visible at the national average. It is visible at the regional level. The state pages below document the regional picture.
Coal plants approved to run past planned dates.
Fly ash is a byproduct of burning coal for electricity, so its regional availability tracks decisions made by utilities and regulators rather than by the concrete industry. Two utilities have moved to run coal plants past planned retirement dates, each by a dated decision.
Kingston,
Cumberland
On February 11, 2026 the TVA Board of Directors voted to run both plants past retirement dates TVA had committed to in Records of Decision. The board cited rapidly increasing electricity demand after a decade of flat demand.
A new cement chemistry, under the same order.
USGS reports that blended cement accounted for 63 percent of total United States cement shipments during the first 9 months of 2025, and that 95 percent of those blended shipments were estimated to be portland limestone cement, ASTM C595/C595M Type 1L. Finely ground limestone replaces a portion of the clinker. The reactivity is different. The water demand is different. The behavior with admixtures is different. The behavior in cold weather is different.
The two changes overlap. The cement changed while the fly ash supply was moving region by region, and nothing on an order form has to change for the material in the truck to change. This is not about anyone's bad faith. There was no requirement anywhere in the chain to document that the chemistry had changed. Not on the batch ticket. Not in the contract. Not at the pour.
Ash harvesting buys time. Its chemistry can differ.
The industry is shifting toward harvesting fly ash from existing on-site landfills (sub-grade or pond ash storage) to extend usable fly ash supply. This buys time. It does not solve the structural supply decline. Harvested ash chemistry can differ from freshly produced ash. Mix designs that perform with fresh ash do not necessarily perform identically with harvested ash.
The crisis, region by region.
Each state below carries its own coal-plant landscape, regional fly ash supply trajectory, and institutional record relevant to residential concrete operating in that state in 2026.
The materials changed. PSIP keeps the record.
On a concrete pour, a PSIP record holds the specified mix design, the cement type, and the supplementary cementitious material by type, or that none is specified, as the contractor states them at setup, before placement. On a pool shell, it holds the batch tickets for each shoot day, the delivery method, wet shotcrete or dry gunite, and the nozzle operator by name, as the builder states it. Every batch ticket is photographed, and the photograph records what the ticket shows. Tickets vary, and many do not list everything in the load, so the contractor adds what he knows in the notes, as his own statement. PSIP records the work and certifies that it was recorded. The contractor is responsible for local building codes, permits and licensing. PSIP certification is not an inspection, a code approval or a warranty. No material supplier can pay for a say in PSIP, and PSIP does not recommend products.