Steel Fibres Effect on the Mechanical Properties and Thermal and Freezing Performance of Lightweight Self-Compact Concrete

In this paper, the effect of steel fibres on the mechanical properties and thermal and freezing performance of lightweight self-compacting concrete consisting of Leca and microsilica gel has been studied. For this reason, the effect of three different contents of steel fibres on rheological and mechanical properties, including compressive, tensile and flexural strengths, and on concrete performance against thermal loading and freezing has been investigated. At the first stage, ten mix designs have been made by changing the amount of water, microsilica gel, stone powder and Leca contents. Then, slump, J-ring, U-box, L-box and V-funnel tests have been done. After selecting the control mix, 7-, 28- and 90-day compressive and tensile strengths tests, 90-day flexural and thermal tests, and 28-day freezing and thawing test have been performed. Obtained results indicate that steel fibres have increased tensile and compressive strengths by 95% and 16%, respectively. They have improved thermal durability at high temperatures and have prevented the loss of compressive and tensile strengths by 13% and 92%, respectively. The existence of steel fibres has enhanced the behaviour of concrete in freezing and thawing cycles by decreasing the loss of compressive and flexural strengths by 8% and 15%, respectively.