Enhanced impact energy absorption in self-healing strain-hardening cementitious materials with superabsorbent polymers D. Snoeck ⇑ , T. De Schryver, N. De Belie Magnel Laboratory for Concrete Research, Department of Structural Engineering, Faculty of Engineering and Architecture, Ghent University, Tech Lane Ghent Science Park, Campus A, Technologiepark Zwijnaarde 904, B-9052 Gent, Belgium highlights  SAP samples were more ductile upon impact compared to reference samples.  Superabsorbent polymers act as stress initiators increasing multiple cracking.  Healing was monitored using natural frequency analysis.  In a relative humidity condition, SAP specimens show healing. graphical abstract HEALING HEALING IMPACT IMPACT article info Article history: Received 31 May 2018 Received in revised form 14 August 2018 Accepted 2 October 2018 Available online 6 October 2018 Keywords: Self-healing Repeated healing Impact loading SHCC Hydrogels Fiber reinforcement abstract Concrete is the most-used man-made construction material worldwide. One of its major flaws remains the susceptibility to cracking upon impact loading. In this study, plates containing different amounts of superabsorbent polymers were impacted at four different ages (1 week, 1 month, 4 months and 6 months) and stored at different healing conditions (wet/dry cycles and 95 ± 5% RH). After 28 days of healing the plates were impacted and healed again. When the deformations during impact and the rebound after the impact were analysed, the specimens containing SAPs showed a more ductile beha- viour during impact loading compared to reference samples. A good healing was confirmed by natural frequency analysis. Even during a second impact loading of healed samples a significant regain in natural frequency was obtained. The evolution of the natural frequencies also showed a superior healing caused by wet/dry cycles compared to healing at 95 ± 5% RH. Only in specimens with SAPs, the healing condition of 95 ± 5% RH resulted in a regain in natural frequencies due to the moisture uptake by the SAPs and sub- sequent healing. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction Cementitious materials may show a low tensile strength, a brit- tle behaviour and crack formation. Cracks are to be avoided as they allow harmful particles in fluids and gases to enter the cementi- tious matrix causing a negative effect on the durability. These brit- tle characteristics are especially important when impact loading is involved. In an advanced stage of damage the only option is to repair or replace the impaired elements. However, this is mostly linked with high restoration and repair costs and a huge amount of discomfort. As a solution, a lot of these problems can be avoided https://doi.org/10.1016/j.conbuildmat.2018.10.015 0950-0618/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: didier.snoeck@UGent.be (D. Snoeck). Construction and Building Materials 191 (2018) 13–22 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat