ACI PRC-237.2

Given the high flowability and relatively fast casting rate of self-consolidating concrete (SCC), such concrete can exert high form pressure. Accurate assessment of form pressure is necessary from safety and economic points of view. The maximum form pressure and pressure decay are dependent on the structural buildup of the concrete at rest following placement, as well as on the placement parameters. The structural buildup at rest is affected by the thixotropy of the mixture. This report presents information on key parameters, including constituent materials; mixture proportioning; and casting parameters such as the casting rate, concrete temperature, and reinforcement percentage, affecting thixotropy and SCC form pressure. Prediction models available for estimating SCC form pressure are presented. Findings from two round-robin field studies conducted to validate these models are also discussed. This report should be of interest to concrete professionals, including concrete suppliers and formwork designers, because it covers: 1) the influence of SCC proportions and casting parameters on form pressure; 2) means to estimate formwork pressure with examples; and 3) techniques to measure formwork pressure in field applications.