Fresh concrete pressure on vertical and inclined formwork systems: full-scale experimental investigations and numerical modeling

Abstract Purpose The lateral pressure of fresh concrete on formwork governs the structural safety and cost efficiency of formwork systems for concrete structures. While the behavior in vertical formworks has been extensively investigated, no systematic experimental data exist for inclined formworks, although they are increasingly applied in modern concrete construction. This study addresses the scientific question of the influence of inclination angle, concreting speed, concrete consistency, formwork width, reinforcement and vibration intensity on the fresh concrete pressure in inclined formwork systems. Methods A large-scale test program was carried out with 15 concreting tests, with vertical and inclined formwork systems being filled simultaneously. Pressure development was continuously monitored using both pressure sensors and anchor force measurements. The influence of fresh concrete properties, formwork width, casting rate, reinforcement and compaction methods was evaluated. In addition, a numerical model was developed to simulate the pressure distribution, calibrated and validated against the experimental data. Results The tests showed that inclined formwork exhibits significantly lower pressures than in vertical systems. These reductions were primarily attributed to increased friction effects and a more pronounced silo effect as well as a lower vibration influence. Systematic dependencies of concrete pressure were observed with respect to the angle of inclination, formwork thickness, concrete consistency, reinforcement, and vibration intensity. Numerical simulations reproduced these effects and provided recommendations for practical use. Conclusion This work provides the first comprehensive database on fresh concrete pressure on inclined formwork. The combined experimental–numerical approach enables more accurate design of formwork systems and offers guidance for future updates of international standards.