Have a ready-mix engineer track the concrete temperature. If the truck arrives cooler than expected, recalculate P_max immediately.
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.
If the form height is 3 m, full hydrostatic would be 72 kN/m². The CIRIA method allows a far lighter formwork system, saving material and labor. ciria report 108 concrete pressure on formwork
Fast pouring rates lead to higher pressures because the concrete does not have time to set before more is added.
Contractors can use the formulas inversely to calculate the maximum safe rate of rise ( Have a ready-mix engineer track the concrete temperature
While highly versatile, CIRIA Report 108 is an empirical framework developed under specific criteria. Designers must be aware of its boundaries:
Four decades after its publication, CIRIA Report 108 remains the most practical, research-backed tool for predicting concrete pressure on formwork. It has saved the construction industry billions in material costs and prevented countless formwork failures. Whether you are designing a retaining wall, a dam, or a high-rise core, understanding and applying is a non-negotiable skill for the modern engineer. Calculate Maximum Pressure ( Pmaxcap P sub m
If you need help checking a specific formwork design, tell me your , rate of rise , concrete temperature , and mix type . I can walk you through the math to find your maximum design pressure. Share public link
The formula only applies up to the height where concrete begins to set. For very tall walls (e.g., 10 m), multiple lift pours are needed, as the lower concrete will have set before the top is placed.
CIRIA Report 108 is built on the understanding that fresh concrete is a —it behaves as a liquid when agitated but gains shear strength as it rests. The key variables affecting lateral pressure are: