108 Concrete Pressure On Formwork | Ciria Report

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

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. The breakthrough