Influence of steel fibre and haydite adding content on the basic mechanical properties of lightweight concrete

13 groups of steel fibre reinforced lightweight aggregate concrete (SFRLAC) with three kinds of strength grades were prepared. The cube compressive strength, splitting tensile strength and axial compressive strength were measured, the stress-strain curves of SFRLSC axial compression were obtained. The results show that the steel fibre can improve the compressive strength of lightweight concrete (LC) slightly, the compressive strength decreases with the increase of the haydite ratio (V_h), and the lower the strength grade is, the greater the degree decreases. Steel fibre have a significant improvement on the splitting tensile strength of LC, steel fibre on the low strength grade LC splitting tensile strength contribution is better than that of high strength grade LC. The splitting tensile strength of the low strength grade SFRLAC (LC30 and LC40) is strongly influenced by V_h, while the high strength grade SFRLAC (LC50) is opposite. When V_h reaches 80%, the V_h is no longer the main factor influencing the splitting tensile strength of SFRLAC, but the enhancement of steel fibres is remarkable. The failure of the specimen shows that steel fibre can improve the plasticity of LC. The reduction effect of the V_h on tensile strength is much greater than that of compressive strength. The relationship between axial compressive strength and cube compressive strength of SFRLAC was established. The SFRLAC stress-strain curves reflect the reinforcing effect of steel fibre and the reduction effect of haycite. The haycite decreases the peak stress and toughness of LC, while the steel fibre mainly enhances the toughness of LC.