When using SCC, many engineers use a modified CIRIA approach with a coefficient between 1.8 and 2.5, or simply default to full hydrostatic pressure (D x H) for formwork safety.
The depth to which internal vibrators penetrate. Mechanical vibration liquefies concrete temporarily, destroying early structure and re-inducing full hydrostatic pressure within the vibrated zone. The CIRIA 108 Calculation Methodology ciria report 108 concrete pressure on formwork
Studies indicate that for certain low-friction formwork, the CIRIA arching criterion (which assumes pressure stops increasing after a certain point) might be less conservative than ACI recommendations. When using SCC, many engineers use a modified
CIRIA Report 108, titled “Concrete Pressure on Formwork,” is a widely cited guidance document that synthesizes research and practice on the lateral pressures exerted by fresh (plastic) concrete against formwork during casting. Its primary aim is to help engineers, formwork designers and site teams predict and safely design formwork systems for vertical and inclined concrete elements. The CIRIA 108 Calculation Methodology Studies indicate that
The formula is:
For normal internal vibration (the standard for most construction), the characteristic maximum lateral pressure is given by:
Here is why this specific report is still relevant on every pour.