This article provides a comprehensive breakdown of CIRIA Report 108—its history, key formulas, practical applications, and why it remains indispensable for safety and efficiency in concrete placement.
When constructing the massive diaphragm walls for Heathrow Terminal 5 (London), engineers faced pours up to 15 meters deep. Ordinary hydrostatic assumptions would have required 200 kN/m² formwork—impractical and expensive.
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.
Strictly control the delivery and pumping speed to ensure the design rate of rise ( ) is not exceeded. ciria report 108 concrete pressure on formwork
) influences pressure. In narrow walls or columns, friction between the concrete and the formwork face—along with internal aggregate interlocking—helps support the weight of the concrete, slightly reducing the lateral thrust. 3. The CIRIA Report 108 Methodology
The size and shape of the pour influence pressure. For example, narrow walls or columns experience different internal friction and arching effects compared to massive block pours.
), because SCC remains highly fluid for an extended duration. 5. Practical Design Tips for Site Engineers This article provides a comprehensive breakdown of CIRIA
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The report provides graphs and empirical relationships to determine this transition depth, typically 1–2 meters for ordinary concrete. Below the setting height, pressure is essentially constant.
The primary criticism of R108 is its age. The concrete mixes tested in the 1980s differ from modern high-performance mixes. Today's self-compacting concrete (SCC) and heavily admixed designs behave differently; SCC, for example, exerts nearly full hydrostatic pressure because it remains fluid longer and lacks the internal friction of standard mixes. R108’s formulas may underestimate pressures for these modern specialized mixes. Establish the planned rate of pour (R) in
CIRIA Report 108 splits vertical formwork elements into two categories because aggregate arching actions behave differently depending on geometry. Both plan dimensions are less than 2 meters. At least one plan dimension exceeds 2 meters. Arching Action
Updates the coefficients to better reflect modern cement types and chemical admixtures.
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