Computational-experimental method for determining the height of steel fiber sedimentation in Ultra-High Performance Self-Compacting Concrete

Abstract

The uniform distribution of steel fibers in self-compacting Ultra-High Performance Steel Fiber Reinforced Concrete is one of the factors that determine the properties of the hardened material. In self-compacting concrete mixes characterized by low yield stress and plastic viscosity, steel fibers can settle under gravity, which can lead to a decrease in strength. In this study, a computational-experimental method is proposed for determining the height of steel fiber sedimentation, as well as the segregation index of a steel fiber reinforced concrete mixture. Mixtures were tested with a superplasticizer content of 1, 1.3, and 1.6% with a slump flow diameter of 288, 356, and 378 mm. According to the results of calculations performed according to the proposed method, it was found that the height of steel fiber sedimentation is 3.1, 5.9, and 22.8 mm in mixtures with a plasticizer content of 1, 1.3 and 1.6%. The calculated value of the segregation index of the steel fiber reinforced concrete is quite close to the experimental one with a correlation coefficient of 0.998. Based on the results obtained, a criterion was proposed for determining the maximum allowable height of fiber sedimentation, taking into account the actual height of the concreted structure, which can be used in the concrete mix design.