Pinball Tendons Crack Closure Technology

Concrete is a popular construction material due to its unyielding nature. Although concrete is resistant to erosion, rotting, and rusting, due to its low tensile strength, reinforced concrete is prone to cracking. Also, because the cracks expand and become bigger over time, they can be a potential risk for concrete elements and lead to the failure of structures. Consequently, effective and early crack-closing and concrete healing can greatly enhance and improve concrete structures’ lifespan. Mechanical closing of the cracks by tendons has been one of the successful solutions. These tendons act based on a stored force in a balanced system. The new generation of tendons being investigated on a laboratory scale is Pinball Tendons (PBT). In addition to the simple activation phase, these tendons can store much more force due to their sleeve being made from steel. The significant feature of PBTs is that they do not need to receive any energy or recharge after the casting in concrete, so their service life lasts until they are activated to close the crack and release the prestressed force. According to the recorded CMOD data in this study, the tendons managed to close more than 65% of the crack aperture. The speed of the crack closure is another positive aspect of PBTs, 90% of crack closure has been done within the first 8 seconds. Because of this performance, in addition to the self-healing during the life span of structures, tendons can be a helpful alternative for repairing and enhancing concrete in sudden events like earthquakes and explosions.