SELF-HEALING ASSESSMENT UNDER TENSILE LOADS OF ULTRA HIGH PERFORMANCE FIBER REINFORCED CONCRETE (UHPFRC)

Ultra-high-performance fiber-reinforced concrete (UHPFRC) offers plenty advantages facing regular concretes, including being environmental friendly. The high content of cement substitute such as blast furnace slag helps this developed UHPFRC on that direction. No further, when combined to the regeneration propriety of self-healing this composite can also be economically attractive by reducing future intervention on repairing the structures built using this type of cementitious composite. The aim of this research was to evaluate the healing phenomenon on an UHPFRC with volume fraction of 1.28% of steel fibers with an effective length of 13mm through two indexes, Index of Self-Healing (ISH) and Index of Damage Recovery (IDR). To reach this purpose, tensile tests were conducted to introduce at each specimen a single and controlled crack at age of 28 days until a crack open of 0.2 mm. These specimen were then submitted to 3 (three) months of wet and dry (WD) cycles [24h/24h] and consecutive final tensile tested to evaluate the mechanical properties of a pre-cracked specimen after several wet and dry cycles. Microscopical analyses were carried out to determinate closure evolution of the crack by the precipitation of calcium carbonate along time.