Fresh concrete lateral pressure decay: Kinetics and factorial design to determine significant parameters

The design of vertical formworks is governed by the lateral pressure exerted by fresh concrete; while maximum lateral pressure is the key parameter for formwork design, the rate of pressure decay and the time needed for pressure stabilization is important for determining formwork removal time; the complexity of the problem is due the large number of factors which affect the rate of pressure decay.This works describes an experimental investigation of columns to determine the variation in the initial lateral pressure decay and in the time needed for pressure stabilization with the following variables: coarse aggregate concentration (different sand to total aggregate ratios were used), the use of a plasticizer, the presences of reinforcement and concrete temperature.In the last part of this work a correlation between setting time and maturity functions with the time needed for pressure stabilization was done.The results show that both thixotropic linked to cement grains nucleation and consolidation and cement hydration influences in lateral pressure decay to the point of stabilization. In references with the initial pressure decay, the presence of reinforcement seems to have a major influence. On the other hand the time needed for pressure stabilization could be correlated with the maturity functions.

► 8 test performed to analyze the lateral pressure decay.
► Lateral pressure decay depends on concrete thixotropy and hydration reaction.
► Reinforcement bars are significant in the initial rate of pressure decay.
► Maturity functions seem to be a good predictor for stripping process.