Concrete pressure on formwork

This report provides guidance on calculating concrete pressures on formwork extending and improving the method used in CIRIA R1 to cover concretes using admixtures and blends or blended cements. Use of the method is demonstrated in six examples - bridge abutment, partition wall, lift shaft, mass concrete retaining wall, bridge column, and V column. Before this guide was published, design charts were limited to ordinary Portland cement concretes, but in recent years greater use has been made of admixtures and blends or blended cements. In addition, the commercial need for faster construction has resulted in a general increase in lift heights and rates of concrete placing. CIRIA instigated a programme of site formwork pressure measurements and compiled a comprehensive data file to contain both the new site measurements and previously obtained data. This was used, alongside recent advances in the understanding of the mechanisms, to formulate an improved method of estimating the concrete pressure on formwork.