Flexural toughness and compressive stress–strain behaviour of pseudoelastic shape memory alloy fibre reinforced concrete

The results of experimental analyses for the full-range compressive and flexural response of concrete reinforced with pseudoelastic shape memory alloy fibres (PSMAFs) are discussed in this paper. PSMAFs were manufactured with two types of end hooks and were used in four different fibre contents ranging between 0.5% and 1.25%, with an interval of 0.25% by volume. Cracking patterns and full-depth crack width profiles of PSMAFs reinforced concrete (PMSA-FRC) were also generated by the 2D digital image correlation (DIC) technique. The results obtained for PMSA-FRC are compared with those of steel fibre reinforced concrete (SFRC). The flexural responses of PSMA-FRC and SFRC were significantly different at fifferent stages of flexural behaviour. Compared to SFRC, PSMA-FRC showed lower flexural strength but considerably higher flexural toughness and deflection capacity. PSMA-FRC also exhibited slightly lower compressive strength (5-8%) and modulus of elasticity (4–10%) than SFRC. However, no significant difference was noticed between PSMA-FRC and SFRC regarding the overall shape of the compressive stress–strain curve, compressive toughness and failure mode. It is also shown that PSMAFs type 2, the fibre with 45° end hook, is more efficient in distributing stress over a larger cementitious matrix area. DIC analyses displayed better control over cracking, improved multiple-cracking performance, and tighter crack profiles for PSMAFs type 2 at all four fibre contents tested in this study.