Ciria Report 108 Concrete Pressure On Formwork May 2026
CIRIA Report 108 (1985) establishes the standard UK methodology for calculating lateral concrete pressure on vertical formwork, utilizing factors like placement rate, temperature, and mix composition to determine maximum pressure. Referenced in BS 5975:2019, the report addresses both hydrostatic and reduced pressure scenarios to optimize formwork design. Purchase the report at the CIRIA Official Bookshop. Concrete pressure on formwork - BS5975:2019 - Prontubeam
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.
Limitations and Criticisms of CIRIA Report 108
No document is perfect. Critics note:
Dependent on the formwork's dimensions and shape; it distinguishes between walls and columns. cap C sub 2 (Material Coefficient):
The report uses a simplified empirical equation to determine the maximum characteristic pressure ( cap P sub m a x end-sub ciria report 108 concrete pressure on formwork
- ACI 347 (USA): The American model generally assumes the concrete remains fluid for a specific duration (e.g., based on the type of cement). It assumes the pressure is hydrostatic for the depth poured within that time window.
- CIRIA 108 (UK/International): The CIRIA model is generally considered more sophisticated regarding the rate of rise. It assumes that even while placing, the concrete is stiff
Conclusion: Why CIRIA 108 Remains Indispensable
Nearly 40 years after its publication, CIRIA Report 108 "Concrete Pressure on Formwork" remains the gold standard for rational formwork design. It shifted the industry from fearful over-design to intelligent, risk-aware engineering.
The Problem CIRIA 108 Solved
In the 1970s and 80s, engineers realized the "fluid head" method was wasting millions on over-engineered formwork. Concrete stiffens as it hydrates. CIRIA 108 introduced the concept of "pressure relief" based on setting time. CIRIA Report 108 (1985) establishes the standard UK
Published by the Construction Industry Research and Information Association (CIRIA), Report 108 fundamentally changed how the industry calculates the lateral pressure exerted by fresh concrete. Even with the advent of Self-Compacting Concrete (SCC) and modern admixtures, the principles laid out in this 1985 report remain the industry benchmark.