Smart Activation System for the Hybrid Tendons Crack Closure Technology

Cracks are a typical characteristic of a concrete structure, formed as a direct consequence of the concrete’s low tensile strength. They represent a risk to the longevity of a concrete structure; over time, under the effects of loads and environmental factors, cracks tend to grow and coalesce. It is widely known that cracks reduce the mechanical properties of, and significantly increase the diffusion of deleterious materials through a concrete structure, thus shortening its service-life. The need for enhanced structural longevity and reduced maintenance costs have driven an increased demand for self-healing technologies. Smart crack-closure technologies can lead to the production of more adaptable structural elements, with reduced associated waste and CO2 emissions. The work will cover the developments of a digitally controlled system that uses smart hybrid tendons (HTs) embedded in concrete to detect and close cracks. In particular the work will focus on the digital activation system for the HTs. This technology comprises a shape memory polymer tubular sleeve hosting a pre-stressed strong core which act together to provide an effective crack-closing action and offer flexural reinforcement to the concrete element. The HTs have been the object of a lab-scale study and the digital activation system will complete their design, paving the way for their use in the real world.