Ciria Report 108 Concrete Pressure On Formwork Jun 2026

To appreciate CIRIA Report 108, one must compare it to other major standards:

The design structure takes the lesser of these two values, capped by a minimum absolute pressure to account for localized surge impacts during discharge. The Standard Equation Format (Note: Exact coefficients C1cap C sub 1 C2cap C sub 2

If a project requires a faster pour rate, the formwork design must be strengthened accordingly. 7. Conclusion

): Temperature directly dictates the hydration rate of cement. Higher temperatures accelerate the chemical reaction, causing the concrete to stiffen and set faster, which reduces the duration and magnitude of the fluid pressure. Conversely, cold weather prolongs the liquid state, increasing the load on formwork. Concrete Density ( ciria report 108 concrete pressure on formwork

Properly rigid formwork prevents bowing, deflection, and grout loss, ensuring the finished concrete meets tight architectural tolerances. CIRIA 108 vs. CIRIA Report R108 vs. CS 164

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The you are pouring (wall or column) The expected rate of pour and ambient temperature To appreciate CIRIA Report 108, one must compare

Base weight of the material alters the hydrostatic pressure profile. Size and Shape of the Formwork

They often over-designed formwork, leading to excessive material costs, or under-designed it for rapid, deep pours.

Where the design pressure $P_max$ is taken as the of the value derived from this equation and the full hydrostatic pressure ($D \cdot H$). Concrete Density ( Properly rigid formwork prevents bowing,

Lower temperatures delay setting (longer liquid phase), resulting in higher pressures.

Rough form liners (e.g., plywood) and stiff formwork can reduce measured pressure compared to smooth steel forms. CIRIA 108 provides reduction factors but recommends caution—friction effects are unreliable.

For decades, the methods in this report have helped engineers optimize the design of formwork, ensuring it is strong enough to hold the concrete while avoiding over-design, which wastes materials and money. 2. Fundamental Principles: Hydrostatic vs. Real Pressure