TECH

Steel-memory brings new technology to the prestressed concrete

Prestressed concrete
Swiss engineers have taken a technology bath in one of the most widespread techniques in the world to reinforce the constructions: the prestressed concrete used in construction.While the reinforced concrete has steel structures in it, the prestressed concrete additionally contains steel cables hydraulically driven and anchored in the concrete itself, which gives an additional reinforcement to the structure.Julien Michels and his colleagues at the Swiss Federal Materials Science and Technology Laboratory (EMPA) replaced reinforcing steel cables with a special steel with shape memory, a material that "remembers" its original shape, returning to it by a temperature trigger.Steel reinforcements in concrete structures are typically hydraulically prestressed, requiring ducts to guide tension cables, force transfer anchors, and hydraulic jacks. It works well, but you can not use it to reinforce works that are already ready, for example.

Steel-memory

Iron-based shape memory alloys, which contract during a preheating, permanently pro - tect the concrete structure when they are installed and return to their original size, which eliminates the need for hydraulic prestressing. Preheating can be done on site using an electric current or infrared radiators.There are already form memory alloys being used in various applications. But since they are typically made of nickel and titanium, they are too expensive for civil construction. This led the team to develop a steel with shape memory.The team tested the technique on a number of projects, both new and old, saying the technology is ready for immediate commercialization: it will be sold as "steel-memory" by the project's industrial partners.

Bibliography:

Flexural strengthening of structural concrete with iron? Based shape memory alloy strips
Julien Michels, Moslem Shahverdi, Christoph Czaderski