Experimental study on lateral pressure of prefabricated block formwork for rock-fill concrete dam

Prefabricated block formwork has been increasingly used in rock-fill concrete (RFC) dam construction. However, the lateral pressure characteristics of such formwork under fresh self-compacting concrete (SCC) have not been fully investigated. This paper presents a systematic experimental study on the lateral pressure exerted by SCC on prefabricated block formwork during casting. Key parameters including slump, slump flow, V-funnel flow time, and ambient temperature were examined. Pressure sensors were installed vertically along the formwork height to monitor the time-dependent pressure development. The results show that: (1) Lateral pressure increases with slump and slump flow, while it decreases with longer V-funnel flow time and higher ambient temperature. (2) Lateral pressure decreases linearly with increasing formwork height and exhibits a highly linear vertical distribution. (3) Pressure rises rapidly at an early stage, increases slowly to a peak, decreases significantly by approximately 25%, and then declines steadily toward a stable value. (4) The maximum lateral pressure occurs at the formwork bottom (stable at about 38 kPa), and the minimum appears at the top (stable at about 15 kPa). This study provides a reliable theoretical basis for the design and application of prefabricated block formwork in RFC dam engineering.