Report 108 Concrete Pressure On Formwork - Ciria

). The generalized approach involves determining a base pressure and applying correction factors based on the variables listed above.

Report 108 distinguishes between the height of the formwork and the pressure envelope. In tall columns, the pressure might reach a maximum peak and then drop off near the bottom because the concrete there has set. In short walls, the pressure might be hydrostatic because the pour finishes before the concrete has time to stiffen. ciria report 108 concrete pressure on formwork

Implementing CIRIA 108 correctly involves a methodical approach to design: In tall columns, the pressure might reach a

One of the most valuable sections explains the phenomenon of particle interference. As concrete stiffens, the aggregate particles begin to arch, transferring load to the sides of the formwork via friction, thereby reducing the pressure on the lower layers. R108 quantifies this reduction, leading to more economical formwork designs compared to assuming full liquid head. As concrete stiffens, the aggregate particles begin to

While highly versatile, CIRIA Report 108 is an empirical framework developed under specific criteria. Designers must be aware of its boundaries:

Research (including later CIRIA updates) shows that for SCC, the coefficient (1.2) is insufficient. SCC can maintain fluid-like behavior for longer, leading to near-hydrostatic pressures.

Most contractors take E from a concrete test certificate done at 20°C. If your pour is at 10°C, E might be 3x longer. Always adjust E for ambient and concrete temperature. A 5°C drop can double E.