Ciria Report 108 Concrete Pressure On Formwork 2021 File
CIRIA Report 108, "Concrete pressure on formwork," serves as a foundational guide for calculating the lateral pressure exerted by fresh concrete on temporary formwork structures, accounting for variables like rate of rise, temperature, and mix composition. It provides specific formulas to determine maximum pressure ( Pmaxcap P sub m a x end-sub
- Takeaway: Report 108 forces the site team to plan the pour rate beforehand. If the contractor speeds up the pour beyond the design rate, the formwork may fail.
Executive Summary
2. Additives and Retarders
average
Internal vibration can locally increase pressure by 20–40% directly around the vibrator head. However, CIRIA 108 notes that proper vibration does not increase formwork pressure if the placement rate accounts for vibration-induced fluidization. The key is to avoid over-vibration, which can segregate concrete and cause blowouts. ciria report 108 concrete pressure on formwork