Production and Testing of Kiln-cast Glass Components for an Interlocking, Dry-assembled Transparent Bridge

A pedestrian glass bridge, located at the TU Delft campus site, is being designed by the TU Delft Glass & Transparency Lab. Specifically, the arch-formed bridge consists of cast glass, dry-assembled, interlocking components. To validate the shape of the components, glass mock-ups in 1:2 scale are kiln-cast and tested. This paper follows the elements’ production process from the 3D milled MDF model and the construction of disposable moulds via the lost-wax technique, to the kiln-casting at 940ºC with the “flowerpot method”. Steps are taken towards the refinement of the production technique, with emphasis in minimizing the occurrence of air bubbles, surface flaws and internal stresses that can reduce the load-bearing capacity of the components. Polarisation techniques are employed to define the residual stress distribution of the cast elements as well as to map the consolidated flow of molten glass and the areas of inhomogeneity or non-cohesion. The structural performance of the components and their interlocking behaviour are studied by conducting shear tests on three series comprising three glass bricks with a transparent PU interlayer in-between. The fracture patterns of the specimens are analysed and correlated with the flaws and internal stresses resulting from the kiln-casting process.