Ciria Report 108 Concrete Pressure On Formwork Jun 2026

12-story reinforced concrete core wall, London Formwork: Crane-lifted gang forms, 2.8 m tall panels Concrete: C35/45, slump 80 mm, rate of placement 3 m/h, temperature 18°C

The appendices provide additional information and examples to support the report's findings and recommendations.

They assumed a linear relationship between concrete placement height and pressure up to a certain limit.

Be careful. CIRIA 108 assumes "vibration" limited to 1.5m below the top. If you over-vibrate or use self-compacting concrete (SCC), the pressure reverts to full hydrostatic. ciria report 108 concrete pressure on formwork

CIRIA 108 defines the as a value between two extremes:

Establish the planned rate of pour (R) in m/h, concrete temperature, and density. Calculate Maximum Pressure ( Pmaxcap P sub m a x end-sub ): Use the formulas to find the maximum lateral pressure.

CIRIA 108 assumes internal vibration is stopped 1.5m below the current concrete level. If you over-vibrate (running the head too deep), you liquify the stiffened concrete, resetting the pressure to hydrostatic at that depth. CIRIA 108 assumes "vibration" limited to 1

The methodology outlines a step-by-step mathematical approach to determine the design lateral pressure, ensuring formwork is neither under-designed for safety nor over-designed to the point of financial waste. Step 1: Determine the Concrete Mix Group

When fresh concrete is placed into forms, it behaves as a fluid, exerting hydrostatic pressure on the sides of the formwork. However, as the concrete begins to hydrate and stiffen, it starts to set and can support itself, gradually reducing the pressure on the form. The key engineering question is:

However, CIRIA 108 remains the foundational logic taught in temporary works coordinator (TWC) courses globally. Its equations are still embedded in the background code of modern proprietary formwork calculation software used by industry giants like Doka, Peri, and Paschal. Conclusion Calculate Maximum Pressure ( Pmaxcap P sub m

With the introduction of the Eurocode (BS EN 12812) for falsework, there is a conflict in methodology. EN 12812 uses a different coefficient approach ($H_max$). However, many practitioners still prefer CIRIA R108 because EN 12812 can be complex to navigate for simple wall pours, and CIRIA is viewed as having a "calibrated" safety record in the UK industry.

Where is the concrete temperature at the time of placing (measured in degrees Celsius).

For a more personalized assessment of your project's formwork, please share: The and temperature The concrete type (e.g., standard, SCC) The maximum pour height