The influence of formwork dimensions and rate of casting of self-consolidating concrete (SCC) on the development and variations of lateral pressure were evaluated using two types of experimental columns; the first measuring 2100 mm in height and 200 mm in diameter, and the second 3600 mm in height and 920 mm in diameter. Variations of heat of hydration and setting time were correlated to the rate of decrease in formwork pressure.Test results show that the scale effect has an influence on the rate of drop in lateral pressure with time. Two distinctive rates of pressure drop were obtained during the plastic and setting stages of hydration. A rate of pressure decrease of 5.3 kPa/hr was obtained during the first 6 hours of time and is mostly associated with the increase in the restructuring process due to the reversible effect of thixotropy. A second distinctive slope of 2 kPa/hr was noted beyond 6 hours until the canceling of pressure, and is related to setting. The increase in the casting rate from 10 to 25 m/hr in the 200-mm diameter column resulted in slightly higher lateral pressure.RésuméL'influence des dimensions du coffrage ainsi que la vitesse de coulage sur les pressions latérales développées par les bétons autoplaçants ont été évaluées sur deux tubes expérimentaux; l'un mesurant 2100 mm en hauteur et 200 mm en diamètre, et l'autre 3600 mm en hauteur et 920 mm en diamètre. Les variations de la cinétique d'hydratation et du temps de prise ont été également déterminées.Les résultats obtenus montrent que la géométrie du coffrage a une influence sur la diminution des pressions avec le temps. Deux différentes pentes de diminution de pression ont été aperçues. La première de 5,3 kPa/h obtenue pendant la période dormante du ciment est essentiellement reliée à un phénomène de restructuration qui est due à l'effet réversible de la thixotropie. La seconde pente de 2 kPa/h attribuée à un effet de prise du ciment est ensuite apparue. L'augmentation de la vitesse de coulage de 10 et 25 m/h dans le tube ayant 200 mm de diamètre a induit une légère hausse des pressions latérales.
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