Empa steel adhesives last 50 years
In a long-term test, Empa engineers have proven the durability of epoxy bonds on steel girders. The test went on for 50 years.
In the large test laboratory of the Eidgenössische Materialprüfungs- und Forschungsanstalt ( Empa ) in Dübendorf, a test has been running for 50 years to examine the long-term behavior of bonded steel reinforcement on a concrete beam. In this long-term test, which is unique worldwide, according to the media release , several reinforced concrete girders were reinforced with steel lamellas glued to the underside. One of the girders, which has been subjected to 87 percent of its predetermined breaking value for 50 years, has so far held out without any problems.
“After 50 years below 87 percent of the average breaking load, the epoxy resin bond shows no weaknesses. This means that bonded steel lamellar reinforcements have passed the long-term test, ”says engineer Christoph Czaderski, who has overseen the test over the past few years.
According to the announcement, the carrier is one of originally six identical specimens, all of which were subjected to different tests. The five other reinforced beams fell victim to fairly successful static fracture and dynamic fatigue tests that exceeded their load limits. The aim of the tests was to find out how well epoxy resin works as an adhesive for attaching a steel lamella to a concrete beam. According to Czaderski, the long-term test shows "practically no shifts" in the adhesive joint after 50 years.
What was new territory at the beginning of the test is now state of the art. The process is important because it allows older buildings to be reliably reinforced instead of being torn down and replaced by new buildings.
Empa's “Engineering Structures” department has been developing and researching new, simple and inexpensive reinforcement methods with modern materials such as epoxy resins, carbon fiber-reinforced plastics and shape memory alloys for many years.