The “Parasols” in Seville feature components that are designed to be glued instead of bolted together. To prevent the adhesive from melting, it needs to withstand temperatures of up to 60 degrees. Researchers have now optimized the adhesive’s resistance to high temperatures.

Umbrellas Metropol will be the centerpiece of the new Plaza de la Encarnación in Seville. In addition to being an attractive work of art, mushroom-type structures also play host to some construction techniques pioneered, even with load-bearing structure composed of finely wrought wood veneer laminated beams. With mechanical means to join excluded for structural reasons, the beams are instead linked by means of glued-in threaded rods. However, high temperatures and the relentless sun of a typical summer in Seville could pose a significant challenge for the glue, in the worst case, it loses its ability to hold the components together.

The type of adhesive used to Seville is designed to withstand temperatures up to 60 degrees, so that researchers from the Fraunhofer Institute for Wood Research WKI worked on behalf of the building inspection authorities to determine how far the heat load is likely to reach this limit. “We raised the temperatures that could occur at the site and used simulations to determine the temperature would trigger in building materials,” says Dirk Kruse, head of department at WKI. “Our results showed that temperatures in the glue might reach nearly 60 degrees, which is obviously too close to the limits of comfort.”

Subsequent tests conducted on three components under test in a climatic chamber confirmed their results, giving rise to a difficult choice: either the adhesive should be improved, or the authorities of the building inspection would be forced to hand over the construction of ’stop. Fortunately, there is a way to improve the resistance of the adhesive at elevated temperatures, namely by “hardening” structural components: “Once the components have been glued in place, they are heated again,” continued Kruse . This announcement causes hardening reactions to occur. “And the result? The glue is less likely to take a liquid form and maintains its stability to a temperature of 70 degrees. This gives a safety margin beyond of thermal stress is actually expected to occur, which means construction can now proceed as planned and will soon Seville with a benchmark brand new.

“These are the types of solutions that allow you to firmly anchor adhesive technology in the construction industry,” says Kruse. While adhesive bonding is widely used in the aerospace industry, the use of ‘adhesion for structural applications in the construction industry is still in its infancy. However, the method opens a myriad of new possibilities for architects.

from:www.sciencedaily.com