Quantification of tribological effects in expansion fasteners

Sammanfattning: Post-installed anchors for civil construction are elements that ensure the integrity of building structures even under the most severe static, seismic and shock loadings. Despite the high popularity of this technology in construction sites all over the world, the current state of knowledge is limited and there is still a great potential for significant improvements. Specifically, expansion anchors’ mechanism relies purely on friction, therefore being able to manipulate and optimize their tribological behavior is key to meet strict safety regulations and develop outperforming and outlasting design solutions. This research project, conducted at Hilti Corporation in Schaan (Liechtenstein), presents an investigation of several antifriction coating solutions. Laboratory-scale tests have been performed to quantify the different coefficient of friction while, with full-scale standardized tests (anchor set in concrete), it has been possible to evaluate the overall mechanical performances of the specimens. Afterwards, the obtained data have been analyzed with numerical software and the samples have been further investigated with optical microscopy. The outcome of this thesis work is crucial for the development of the next generation of expansion fasteners and gives additional insights for a deeper understanding in the tribology of functional coatings.