Development and experimental verification of a design method for steel fibre-reinforced high strength lightweight self-compacting concrete

This paper proposes a three-stages mixture design method for steel fibre-reinforced high strength lightweight self-compacting concrete (SHLSCC). The first stage consists in the paste and granular skeleton optimisation. The paste composition is determined by consistency tests and the solid skeleton is obtained by packing different amounts of aggregates. The fibres are included in the particle size distribution using the equivalent diameter concept. In the second stage, the material quantities for one cubic metre of concrete are calculated, and in the third stage, the parameters in test mixes are adjusted. The design criteria adopted for the material are defined by the fulfilment of self-compacting and compressive strength requirements. To evaluate the method's applicability, six mixtures containing a coarse lightweight aggregate with different proportions of hooked-end steel fibres (i.e., 0.25 %, 0.51 %, 0.65 %, 0.76 %, and 1.00 %) were prepared. The effect of the steel fibre content on the development of the filling ability, passing ability and segregation resistance was studied. The results showed a slump flow within 650–750 mm without segregation. All mixes showed a 28-day compressive strength above 40 MPa and a density within 1800–1900 kg/m 3 . The fibre reinforcement increased the mechanical properties under splitting tensile strength and flexural toughness performance. The results for the designed mixes show that this new dosing methodology enables the quantitative determination of raw material content, as well as control of the mixture’s filling capacity, passing capacity, and segregation resistance, to produce high-performance SHLSCC. • New mixture design method for steel fibre-reinforced high strength lightweight self-compacting concrete (SHLSCC). • The proposed mixture procedure was based on packing and mortar film thickness theories. • Validation through six mixtures containing a coarse lightweight aggregate with different proportions of steel fibres. • Evaluation of effect of the steel fibre content on the properties in fresh and hardened states. • The new method enables the quantitative determination of the content of raw materials.