Properties of Steel Fibre Reinforced Self-compacting Concrete for Optimal Rheological and Mechanical Properties in Precast Beams

In the paper the basic influence trends of different composition and properties of steel fibres on fresh mixture and mechanical properties (compressive and flexural strength researching in different length of precast beams) of Self-Compacting Concrete (SCC). Discussion about the results covers mechanism of fibres influence on mechanical effectiveness of moulding precast beams. Presented relations can be used for selecting of optimal admixtures in presence of steel fibres, as well as for control of properties of fresh SCC containing fibres. The research has shown the negative influence of fibres added to concrete mix on its rheological properties and workability. Optimal addition of superplasticizers (SP) improves its properties, and becomes positive as an additive to concrete mixes. The current state of knowledge is not sufficient to effectively control the mixtures with fibres according to rheological and mechanical properties. It compels to recognize the real nature of workability and to determine the impact of SP and fibres on phenomena taking place in fresh and hardened self-compacting concrete. The goal of this work was to determine the distribution and orientation of steel fibres in self-compacting concrete, cast of small beams by filling the mould with mixture in one edge, and to investigate their mechanical properties.