Ciria Report 108 Concrete Pressure On Formwork ((better)) -

This is often the most contentious variable on site. If a crane is pumping concrete rapidly, $R$ is high, leading to high calculated pressure. If the pour is slow (perhaps delayed by a pump blockage), $R$ drops, and pressure drops.

Improved pumping technology allowed for much faster vertical rise rates ( ), creating higher hydrostatic heads.

CIRIA Report 108 (1985) provides the industry-standard semi-empirical model for calculating lateral concrete pressure on formwork, incorporating variables like placement rate and mix design to avoid over-engineering. The report, which superseded earlier guidelines, defines maximum design pressure ( Pmaxcap P sub m a x end-sub

This calculated pressure of 53.85 kN/m² is significantly lower than the hydrostatic pressure ($D \cdot H = 25.0 \times 3.30 = 82.5 \text kN/m^2$), demonstrating the substantial economic benefit of using this more refined method. ciria report 108 concrete pressure on formwork

Directly adopts CIRIA 108 methodologies for its temporary works recommendations.

A maximum ceiling limit based on the full fluid behavior over a specific operational height, adjusted for structural dimensions.

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 This is often the most contentious variable on site

The total vertical height of the discharge pour limits the absolute maximum pressure. The pressure can never exceed the full hydrostatic value of the fluid column. Concrete Density and Admixtures

To determine the design pressure, the engineer calculates two distinct limits: Where is the density of the concrete and

They often over-designed formwork, leading to excessive material costs, or under-designed it for rapid, deep pours. Improved pumping technology allowed for much faster vertical

Segmented formulas based on pour rate, chemistry, and wall vs. column classification.

Pmax=ρ⋅g⋅Hcap P sub m a x end-sub equals rho center dot g center dot cap H (Where is concrete density, is gravity, and

The report is structured to take the user from the fundamental properties of concrete to the final design pressure.