Ciria Report 108 Concrete Pressure On Formwork 【2025-2026】

Introduction CIRIA Report 108, titled Concrete Pressure on Formwork , is a cornerstone document in structural and temporary works engineering. Published by the Construction Industry Research and Information Association (CIRIA) in 1985, this report revolutionized how engineers calculate the lateral pressure exerted by fresh concrete on vertical formwork faces.

This article breaks down every aspect of CIRIA 108, explaining how to apply its formulas, why it outperforms older standards like ACI 347, and how to prevent formwork failure on your next pour.

24 kN/m³ × 2.8 m = 67.2 kN/m² CIRIA 108 pressure: P_max = 7.2 × (3/18) + 18 = 7.2 × 0.167 + 18 = 1.2 + 18 = 19.2 kN/m²

| 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 | ciria report 108 concrete pressure on formwork

For critical applications or unusual conditions, consulting the full 32-page report, including its detailed coefficient tables and worked examples, remains strongly recommended.

Most contractors take E from a concrete test certificate done at 20°C. If your pour is at 10°C, E might be 3x longer. Always adjust E for ambient and concrete temperature. A 5°C drop can double E.

To determine the design pressure, the engineer calculates two distinct limits: Where is the density of the concrete and Introduction CIRIA Report 108, titled Concrete Pressure on

Use the lowest expected placing temperature to remain conservative.

Comparison graph of concrete pressure on formwork showing CIRIA 108 plateau vs hydrostatic pressure.

Article last updated: [Current Year] – for educational and professional use. Always verify with local codes and current standards. 24 kN/m³ × 2

The formula is:

A maximum ceiling limit based on the full fluid behavior over a specific operational height, adjusted for structural dimensions.