Effect of a crystalline admixture on the self-healing capability of high-performance fiber reinforced concretes in service conditions

In presence of water, cracks of reinforced concrete structures can heal naturally or with the help of admixtures. The project aimed to measure the water permeability and self-healing of a high-performance concrete (HPC), a HPC with fibers (HPFRC) and a HPC with fibers and crystalline admixture (HPFRC-CA). Under monotonic loading, HPFRC and HPFRC-CA showed maximal crack widths 39% lower and water permeability 3.1 times inferior than HPC. Under a 7-day constant loading and a continuous water flow, cracks of HPFRC and HPFRC-CA were completely healed in comparison to 60% for those of the HPC. The self-healing kinetics was slower for the HPFRC-CA than for the HPFRC, but a higher load had to be applied in the HPFRC-CA to reach again the initial permeability. SEM observations of self-healed products allowed identification of calcite and ettringite in the HPFRC in comparison to aragonite in the HPFRC-CA.