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 designed by the TU Delft Glass & Transparency Lab. The arch-formed bridge consists of cast glass, dry-assembled, interlocking components. To validate the components’ shape, glass mock-ups are kiln-cast and tested. This paper follows the elements’ production process from the milled MDF model and the construction of disposable moulds via the lost-wax technique, to the kiln-casting at 940C 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 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 the interlocking system is studied by conducting a 4-point bending test on an arch specimen comprising 20 glass bricks with a transparent PU interlayer in-between. The results are compared with similar tests conducted with glass units produced by other methods, such as waterjet cutting or hot-pouring.