To address this, the Construction Industry Research and Information Association (CIRIA) commissioned a program of site measurements and data analysis. The result was , published in 1985 by authors C.A. Clear and T.A. Harrison. It extended and improved the method from the earlier CIRIA Report 1 (1965) to provide a reliable, research-backed method for calculating concrete pressure on formwork, usable with a wide range of modern concrete mixes.
High-dose retarding agents and advanced superplasticizers alter hydration kinetics beyond what the original CIRIA 108 charts anticipated. 5. Practical Site Tips for Formwork Safety
Before the publication of CIRIA Report 108, engineers primarily relied on simplified equations, such as those provided by early American Concrete Institute (ACI) standards or the older CIRIA Research Report 46. While these early methods were straightforward, they possessed significant limitations:
Have a ready-mix engineer track the concrete temperature. If the truck arrives cooler than expected, recalculate P_max immediately.
I can provide more detailed structural guidance on this topic if you tell me: ciria report 108 concrete pressure on formwork
[ K = \left( \frac36T + 16 \right)^2 ]
CIRIA Report 108, Concrete Pressure on Formwork (1985), provides a widely adopted methodology for calculating lateral pressure exerted by fresh concrete on vertical formwork. Utilizing a semi-empirical formula based on factors like pour rate and concrete density, the report helps determine maximum design pressure while accounting for modern cement types and admixtures. The guide serves as a key reference for temporary works, defining hydrostatic limits and pressure envelopes for concrete construction. For more details, visit CIRIA.
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While newer materials like Self-Compacting Concrete have pushed the boundaries of the report's original data set (requiring supplemental guidance like CIRIA C660), the fundamental mechanics established by Clear and Harrison remain valid. For the engineer on site tomorrow, CIRIA 108 is the first line of defense against one of construction's oldest problems: keeping wet concrete where it belongs. To address this, the Construction Industry Research and
Where the design pressure $P_max$ is taken as the of the value derived from this equation and the full hydrostatic pressure ($D \cdot H$).
Hydrostatic check: D × H = 24 × 8 = 192 kN/m². Since 115.2 < 192, the CIRIA value controls. You can design formwork for 115 kN/m², not 192. That is a in required tie strength.
Published by the Construction Industry Research and Information Association (CIRIA), Report 108 remains the gold standard for calculating lateral pressure exerted by fresh concrete on vertical and inclined formwork systems. Despite being originally released in the 1980s (with updates in subsequent years), its principles continue to inform modern design codes, including ACI 347 and EN 12812.
| Feature | CIRIA 108 (UK/Global) | ACI 347 (US) | | :--- | :--- | :--- | | | Setting time (E) and Rate (R) | Column size and pour rate | | Pressure Equation | P = 1.2 x D x R x E | P = D x (C1√R + C2) | | Minimum Value | 25 kN/m² | 30 kPa (624 psf) | | Best For | Walls, deep sections, controlled rates | Columns, moderate pours | Harrison
Provides structural and temporary works engineers with a standardized framework for structural calculations. 2. Key Variables Driving Concrete Pressure
For walls, the pressure increases linearly with depth up to a maximum value, defined by factors related to the placement speed and temperature.
The expected and minimum ambient temperature on site