108 Concrete Pressure On Formwork - Ciria Report

This article is for informational purposes. Always refer to the official CIRIA Report 108 and consult with a qualified structural engineer for specific formwork designs.

As cement hydrates, the concrete loses workability and begins to stiffen. This chemical transformation matrix limits how much hydrostatic pressure can build up over time. Temperature of the Mix

Adopt the lower value between the calculated empirical Pmaxcap P sub m a x end-sub and the full hydrostatic pressure head. Legacy and Modern Status

Where:

| Concrete Type | C₂ Value | |---|---| | OPC, RHPC or SRPC without admixtures | 0.30 | | OPC, RHPC or SRPC without admixtures (except retarder) | 0.30 | | OPC, RHPC or SRPC with retarder | 0.45 | | LHPBFC, PBFC, PPFAC or blends with less than 70% ggbfs or 40% pfa, without admixtures | 0.45 | | Blends with less than 70% ggbfs or 40% pfa, with any admixture (except retarder) | 0.45 | | Blends with less than 70% ggbfs or 40% pfa, with retarder | 0.45 | | Blends containing more than 70% ggbfs or 40% pfa | Consult specialist |

Lower temperatures slow the hydration process, keeping concrete in a fluid state longer, which increases pressure.

This article provides a comprehensive overview of CIRIA 108, exploring its background, principles, and application in modern construction. 1. Introduction to CIRIA 108 ciria report 108 concrete pressure on formwork

Further action

Plug the variables into the empirical equations.

Heavier concrete mixes increase pressure. Modern chemical admixtures (like retarders or plasticizers) that keep concrete fluid for extended periods will also keep lateral pressures high for longer durations. 3. The CIRIA 108 Calculation Method This article is for informational purposes

Slump/workability: Higher slump mixes exert greater lateral pressure; low-slump mixes behave less fluidly and transfer lower peak pressures.

Any unexpected changes in the concrete delivery (such as a sudden switch to a highly retarded mix) require a re-evaluation of the formwork capacity.

Purpose: Provide practical methods for estimating lateral hydrostatic-like pressure from fresh concrete, and for selecting/designing formwork and bracing to resist that pressure during placing and early setting. This article provides a comprehensive overview of CIRIA

Introduced precise mathematical limits based on rising rate ( 5. Modern Status: From 108 to Guide CS030