Ciria Report 108 Concrete Pressure On Formwork Today

While the original 1985 Report 108 revolutionized temporary works design, changes in material science eventually necessitated updates.

Lower temperatures delay setting (longer liquid phase), resulting in higher pressures.

For decades, has stood as the definitive industry standard for calculating these pressures. Published by the Construction Industry Research and Information Association (CIRIA) in 1985, this document revolutionized formwork design by replacing overly conservative empirical formulas with a rational, multi-variable approach that accurately reflects real-world construction practices. The Evolution of Formwork Pressure Calculation ciria report 108 concrete pressure on formwork

The CIRIA 108 method applies to:

CIRIA Report 108 (1985) serves as the UK industry-standard guide for calculating lateral concrete pressure on formwork, utilizing a semi-empirical formula that accounts for placement rate, concrete density, and temperature. The report distinguishes between wall and column pressures and covers the impact of modern admixtures, though it may be conservative for highly flowable self-compacting concrete. The report is available through the CIRIA bookstore . Concrete pressure on formwork (R108) - CIRIA While the original 1985 Report 108 revolutionized temporary

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:

The genius of Report 108 lies in its classification of concrete based on "stiffening time." The report recognizes that concrete does not set instantly. It defines categories (Tables within the report) that correlate temperature and mix properties to how quickly the concrete transitions from a fluid to a solid state. The report is available through the CIRIA bookstore

Report 108 distinguishes between the height of the formwork and the pressure envelope. In tall columns, the pressure might reach a maximum peak and then drop off near the bottom because the concrete there has set. In short walls, the pressure might be hydrostatic because the pour finishes before the concrete has time to stiffen.

This calculated pressure of 53.85 kN/m² is significantly lower than the hydrostatic pressure ($D \cdot H = 25.0 \times 3.30 = 82.5 \text kN/m^2$), demonstrating the substantial economic benefit of using this more refined method.

Prevent catastrophic blowouts that endanger site workers.