Experimental and Analytical Study of Impact Failure Strength of Steel Hybrid Fibre Reinforced Concrete Subjected to Freezing and Thawing Cycles

In this paper, an experimental campaign was carried out to assess the impact failure strength of steel hybrid fibre reinforced concrete (SHFRC) subjected to freezing–thawing cycles in water containing 4.0% solution of NaCl. For this purpose, six different concrete mixtures were prepared by adding long and short steel fibres at 2.0% volume of concrete. The proportion of long to short straight steel fibres, also called as the hybrid fibre coefficient (HFC) of SHFRC, used in this study are 0, 0.25, 0.5, 0.75 and 1.0. All the specimens were subjected to freezing–thawing of 0, 25, 50, 75, 100, 125, 150, 175 and 200 cycles followed by impact test using pendulum impact device. Significant weight loss was observed in SHFRC specimens exposed to freezing–thawing cycles (0–200). Also, an analytical model was developed to assess the impact failure strength of SHFRC subjected to freezing–thawing cycles. The results revealed that when the number of freezing–thawing cycles were increased, the loss in weight of SHFRC specimens was increased and the impact failure strength of SHFRC specimens was decreased. The impact failure strength of SHFRC incorporating higher amount of long fibres was higher compared to short fibres, which implies that long fibre plays a predominant role in enhancing its impact failure strength.