), assuming a hydrostatic pressure envelope that reaches a constant maximum value toward the bottom of the pour. ScienceDirect.com The design pressure is calculated as the smaller of: Full Hydrostatic Pressure: is density and is height). The CIRIA Formula: (simplified version). Key Variables in the Formula: (Rate of Rise): The vertical speed at which concrete is placed (m/h). cap C sub 1 (Size/Shape Coefficient):
Limitations and application notes
Reduction with time/setting: As concrete stiffens, lateral pressure decreases. The rate of reduction depends on mix chemistry, temperature, and admixtures (notably accelerators or retarders). ciria report 108 concrete pressure on formwork
Consider "horizontal layering" (pouring in lifts of 1-2 meters with a 30-minute delay between lifts). This allows lower layers to set, drastically reducing pressure on the bottom tie-rods. ), assuming a hydrostatic pressure envelope that reaches
Four decades after its publication, CIRIA Report 108 remains the most practical, research-backed tool for predicting concrete pressure on formwork. It has saved the construction industry billions in material costs and prevented countless formwork failures. Whether you are designing a retaining wall, a dam, or a high-rise core, understanding and applying is a non-negotiable skill for the modern engineer. Key Variables in the Formula: (Rate of Rise):