From crack closure to durability improvement of cementitious mortar with knotted shape memory polymer (k-SMP) fibres

Extending the service life of concrete structures is increasingly important in the effort to reduce carbon emissions. Cracks compromise durability by accelerating degradation mechanism. Embedding shape memory polymer (SMP) fibres in cementitious materials offers a promising solution, as these fibres shrink upon thermal activation and induce crack closure. However, the influence of SMP fibre addition on the durability performance of cementitious materials has not yet been fully explored. In this study, knotted SMP fibres were embedded in mortar specimens, and durability was assessed through water flow testing, chloride diffusion, and carbonation measurements. Following thermal activation, SMP specimens achieved a perfect sealing efficiency, whereas water leakage persisted in reference samples, even after 14 days of wet/dry cycling. The reduced crack widths in the SMP specimens also limited the ingress of chloride ions and CO 2 at the crack location. Overall, the performance of the SMP series demonstrated a superior durability performance. • Crack closure of SMP samples was induced by thermal activation. • Perfect sealing efficiency was achieved for SMP specimens after thermal activation. • Reduced chloride ingress into the crack for SMP specimens was measured. • A reduced influence of a crack on the carbonation front of SMP specimens was recorded.