Effect of self-healing behavior and self-healing technologies on the structural characteristics of cracked RC/ECC composite beams

The improving potential of self-healing behavior and self-healing technology to degradation of structural characteristics of cracked reinforced concrete structures was explored at the member level. Reinforced concrete/engineered cementitious composite (RC/ECC) composite beams were prepared by three self-healing technologies, including crystalline additives (CA), two types of superabsorbent polymers (SAP), and beam without self-healing technology was used as reference specimens. The self-healing properties of structural characteristics of beams were studied by four-point bending tests, including bear capacity, stiffness, ductility index, energy absorption capacity (EAC), and failure mode. The self-healing behavior of damage was evaluated by ultrasonic wave test and damage identification test based on natural frequency. Self-healing behavior of four types of RC/ECC composite beams improved the structural characteristics after cracking to varying degrees. The stiffness of CB-0, CB-S, CB-C, and CB-SH after self-healing increased by 10.80%, 22.88%, 36.71%, and 28.80% compared to that without self-healing, respectively. Recovery ability of structural characteristics of RC/ECC composite beam is enhanced by self-healing technologies. Moreover, CA exhibits a superior improvement in the recovery ability of the structural characteristics compared with two types of SAP. Moreover, the natural frequency and ultrasonic velocity of pre-cracked beams after self-healing were higher than those without self-healing, especially when self-healing technologies were applied. There is a positive correlation between the recovery ability of ultrasonic velocity and self-healing behavior of the structural characteristics of RC/ECC composite beams. This also explains why the structural characteristics of pre-cracked beams have been improved to varying degrees due to different self-healing techniques.