Ciria Report 108 Concrete Pressure On Formwork

Even more critical than R. CIRIA 108 defines "initial set" as the point when concrete reaches a penetrometer resistance of 0.5 N/mm² (roughly when you can no longer easily press a thumbprint into it).

ACI 347 uses empirical curves based on column size. CIRIA 108 is more scientific for walls and unusual geometries because it explicitly accounts for the concrete's hydration chemistry. For complex projects, many engineers run both and use the higher (safer) value. ciria report 108 concrete pressure on formwork

The report recommends a for vertical formwork, as opposed to a full hydrostatic triangle: Even more critical than R