Self-healing of slag-cement ultra-high performance steel fiber reinforced concrete (UHPFRC) containing sisal fibers as healing conveyor

This paper presents the results of a research on the influence of sisal fibers on the self-healing capacity of slag-cement UHPFRC reinforced with steel fibers. In order to evaluate the composite healing capacity, specimens were submitted to pre-cracking by tensile test and then to a 3 months of wetting and drying cycles treatment. Treated specimens were resubmitted to tensile test and evaluated by Optical and Electronic microscopy and CT Scan. Results indicate that the sisal fiber works as a healing conveyor improving by about 20% and 15% the tensile stress and post cracking energy of treated specimens, respectively. Sisal fibers played a major role densifying the interface, working as a vehicle for the healing agents into small interface cracks. All specimens with cracks under 80 μm could completely self-seal mainly by calcium carbonate. Wider cracks could not be completely sealed, though the specimens exhibited a recovery of the mechanical behavior essentially due to late slag-cement hydration. •Environmental friendly ultra-high performance slag-cement concrete proved to reach high tensile and compressive tension.•Self-healing occurs due to late hydration of anhydrous slag-cement and development of calcium carbonate.•Sisal's fibers work as a conveyor for late hydration as well as calcium carbonate nucleation.•Vegetable fibers enhance the self-healing phenomenon.