Ciria Report 108 Concrete Pressure On Formwork

CIRIA Report 108: The Definitive Guide to Concrete Pressure on Formwork

Introduction: The Hidden Force in Concrete Construction

In the world of construction, few forces are as misunderstood—or as dangerous—as fresh concrete pressure on formwork. Every year, projects face blowouts, bulging forms, and even catastrophic failures because engineers and contractors underestimate the liquid-like pressure exerted by newly placed concrete. For decades, the industry struggled with inconsistent guidelines until a groundbreaking document changed everything: CIRIA Report 108, "Concrete Pressure on Formwork."

Appendix A: Calculation example using the "H" method
Appendix B: Case study - Concrete pressure on formwork for a high-rise building project

The Upper Limit: Full hydrostatic pressure (rarely reached unless pouring extremely fast or using retarding admixtures).
The Lower Limit: Zero pressure (fully hardened).

Fresh out of university, we all learned the classic formula: Pressure = Density x Height ( ( p = \rho gh ) ). But anyone who has watched a formwork blowout knows that fresh concrete isn’t a fluid. ciria report 108 concrete pressure on formwork

The appendices provide additional information and examples to support the report's findings and recommendations. CIRIA Report 108: The Definitive Guide to Concrete

Importantly, the report states that pressure never exceeds the full hydrostatic head (ρgh ≈ 24 × height in kN/m²), and it sets a minimum pressure for low rates or high temperatures. Appendix A: Calculation example using the "H" method

Practical Implications & Limitations

Advantages of Using CIRIA 108: