Compression specific toughness of normal strength steel fiber reinforced concrete (NSSFRC) and high strength steel fiber reinforced concrete (HSSFRC)

Compression toughness tests were carried out on concrete cylinders reinforced with three different aspect ratios of hooked-end steel fibres 60, 75, and 83 and six different percentages of steel fibres 0.5, 1.0, 1.25, 1.5, 1.75, and 2.0% by volume of concrete. The w/c ratio used for the normal strength steel fibre reinforced concrete mixes (NSSFRC) was 0.55, and the water-cementitious ratio (w/c+s) for the high strength fibre reinforced concrete mixes (HSSFRC) was 0.31. For each mix, three test cylinders were tested for compression specific toughness. The effect of fibre reinforcement index: volume of fibres x length/diameter ratio on compression specific toughness and also on the relationship between these two properties is presented. As a result, (a) equations are proposed to quantify the effect of fibres on compression toughness ratio of concrete in terms of FRI, (b) equations obtained in terms of FRI and compression specific toughness of plain concrete to estimate both compression specific toughness of NSSFRC and HSSFRC (N.m), (c) equations obtained which represent the relationship between compression toughness index and FRI for NSSFRC and HSSFRC, respectively, and (d) equations obtained to quantify the relationship between compression specific toughness index and fibre reinforcement index for NSSFRC and HSSFRC, respectively. The proposed equations give good correlation with the experimental values.