Ciria Report 108 Concrete Pressure On Formwork ((new)) -
Understanding Concrete Pressure on Formwork: A Guide to CIRIA Report 108
Contractors can use the formulas inversely to calculate the maximum safe rate of rise (
That’s where comes in. Despite being nearly 40 years old, it remains the gold standard guidance for calculating lateral pressure on vertical formwork in the UK and beyond.
Where:
The lateral pressure increases linearly with depth up to a maximum value ( Pmaxcap P sub m a x end-sub ciria report 108 concrete pressure on formwork
According to CIRIA 108, several variables significantly impact the maximum lateral pressure ( Pmaxcap P sub m a x end-sub ) exerted on formwork:
To appreciate CIRIA Report 108, one must compare it to other major standards:
The report provided a range of C₂ values for different concrete types:
In modern practice, users often look for updates to this classic text. While CIRIA Report 108 laid the groundwork, it was heavily incorporated into later standards like the Concrete Society's and CS 164 . Additionally, modern European standards (such as BS EN 12812 for falsework) refer back to these core pressure calculation principles. Despite newer publications, the empirical constants and physics-based logic of CIRIA 108 remain highly respected and widely integrated into modern structural engineering software. Understanding Concrete Pressure on Formwork: A Guide to
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.
: Currently considered a standard reference in the UK and internationally, often cited alongside standards like BS 5975 . The CIRIA 108 Calculation Model
). The generalized approach involves determining a base pressure and applying correction factors based on the variables listed above.
Report 108 introduces a formula for calculating maximum design pressure: While CIRIA Report 108 laid the groundwork, it
Freshly poured concrete behaves initially as a heavy liquid, exerting hydrostatic pressure against vertical forms. As time passes, the concrete undergoes hydration, loses workability, and begins to set, transitioning from a fluid to a self-supporting solid.
If you have a slow-setting retarder (common in summer), CIRIA 108 allows for zero pressure relief. Your formwork ties must be designed for full fluid head.
$P_d = D \cdot \left[ C_1 \cdot \sqrtR + C_2 \cdot K \cdot \sqrt(H - C_1 \cdot \sqrtR) \right]$
Adopt the lower value between the calculated empirical Pmaxcap P sub m a x end-sub and the full hydrostatic pressure head. Legacy and Modern Status
For walls, the pressure increases linearly with depth up to a maximum value, defined by factors related to the placement speed and temperature.