Methodology of Analysis of Fibre Sedimentation in HPC mixtures

The aim of this work is to propose a methodology for evaluating inhomogeneity due to the sedimentation of fibres in High-Performnce Concrete (HPC) mixtures. HPC mixtures makes better mechanical-physical properties than ordinary concrete. To achieve higher strengths, the fine-grained matrix is reinforced with the reinforcement - fibres. The type of used fibres and their homogenization in mixture has an influence on the final mechanical properties of HPC mixture. Four concrete mixtures with same component proportion was chosen for experiments. Water was the only one component, that was changing in mixture recipes. Steel fibres with a ratio of the diameter to length = 0.3/20 were used as reinforcement. The fibre volume in mixture was 1.5 %. The microscopy analysis was used for evaluation of the fibre distribution in the test specimens. It was obtained, that the concentration of the fibres increases with distance from the surface to the bottom of the HPC structure and this non-homogeneity increases with higher water dosage. The dependence of sedimentation of fibres on composition of HPC mixtures can be used for evaluation and optimization of final mechanical properties of the HPC structures.