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 The report, which superseded earlier guidelines, defines maximum design pressure ( Pmaxcap P sub m a x end-sub
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.
What is concrete pressure on formwork?
Example calculation:
The core of the report is the design pressure formula. For internal vibration (the standard method of compaction), the design pressure $P_max$ is given by: ciria report 108 concrete pressure on formwork
Calculation: P_max = 1.2 × 24 × 2 × 2 = 115.2 kN/m²
CIRIA Report 108 (1985) provides a standard method for calculating lateral concrete pressure on vertical formwork using a bilinear model that accounts for modern construction variables like mix design, temperature, and placement rate. The formula, which calculates maximum pressure ( Pmaxcap P sub m a x end-sub What is concrete pressure on formwork
CIRIA Report 108 remains the definitive guide for calculating lateral pressures of fresh concrete on vertical and inclined formwork in the UK construction industry. While it predates the current European standards (EN 12812), it is widely regarded as the most practical and reliable document for this specific aspect of temporary works design. It bridges the gap between complex rheological theory and the pragmatic needs of a site engineer.