Pressure On Formwork - Ciria Report 108 Concrete

The breakthrough? They proved that —and that stiffening starts far earlier than previously thought, even at high slump. Their final equation (the “CIRIA method”) linked pressure directly to pour rate and temperature, not just slump.

But here’s the twist the industry still talks about: Why? Because the proposed design pressures were lower than ACI’s for slow pours but higher for fast pumped pours. That meant formwork contractors would need more strength for rapid construction—costing more upfront. Major formwork suppliers lobbied to suppress the findings. Only after the UK Health and Safety Executive threatened to mandate the method for all public works did it finally publish. ciria report 108 concrete pressure on formwork

Today, CIRIA 108 is the backbone of formwork design in Europe, the Middle East, and Australia. And that failed hospital wall? A plaque now hangs near the rebuilt wing: “This structure stands on the ruins of old assumptions.” If you’d like, I can also share a or compare it to ACI 347. The breakthrough

Led by Dr. Peter Clear and Colin Harrison, the research team did something radical: they built a 6-meter-high experimental formwork rig at the Cement and Concrete Association’s lab. They poured over 50 walls with different rates, temperatures, and mixes, embedding pressure cells that recorded every second. But here’s the twist the industry still talks about: Why

Here’s an interesting, lesser-known story behind , titled “Concrete Pressure on Formwork” (published in 1985). The Story: How a Collapsing Hospital Wall Rewrote Formwork Rules In the late 1970s, a new hospital wing was being cast in the UK. During a tall wall pour, the formwork suddenly blew out—halfway up, the plywood faces bulged, then burst. Wet concrete flooded the rebar cage, injuring several workers. The investigation revealed a shocking truth: the forms had been designed using outdated American Concrete Institute (ACI) pressure formulas that assumed a slow, layer-by-layer pour. But the contractor was using a modern concrete mix with superplasticizers and pumping from the bottom—two factors that dramatically increased lateral pressure.