Material compositions and production methods for solid cast glass components


  • Faidra Oikonomopoulou TU Delft, Architecture and the Built Environment



Glass can be made by different manufacturing processes and by numerous of varied recipes that in return provide the material with different properties. Owing to their workability in lower melting temperatures and the corresponding decreased manufacturing costs, soda-lime and borosilicate glass types are preferred for cast glass applications in structures. Glass can be cast in two ways: primary and secondary casting. In primary casting, glass is molten from its primary raw ingredients, whereas in secondary casting, solid existing pieces of glass are re-heated until the (semi-) liquid mass can flow and be shaped as desired. The main process of primary casting is hot-forming (melt-quenching) and of secondary casting is kiln-casting. The principal difference between the two methods, besides the initial state of glass, is the required infrastructure. In hot-forming, molten glass from a furnace is poured into a mould and is then placed in another, second furnace for annealing. In contrast, kiln-casting employs a single kiln for the melting of the (already formed) glass into the moulds and for the subsequent annealing process and requires lower operating temperatures. In both methods the annealing process is similar. The annealing schedule is influenced by numerous factors that cannot be easily simulated as a complex non-linear time dependent multi-variable analysis is required. As a result the annealing schedule of large 3-dimensional cast units is commonly empirical. Different mould types, disposable or permanent, can be used for casting glass objects. The choice of mould mainly depends on the production volume and desired level of accuracy of the glass product, and is in practice usually cost and time driven. Currently, there is no standard to determine the design strength of solid cast glass objects for structural applications in architecture. Based on the assumption that the increased volume of cast glass can lead to a higher amount of randomly distributed flaws in the mesostructure, the bending strength of cast glass is expected to be comparable but slightly less than that of standard float glass.

Author Biography

Faidra Oikonomopoulou, TU Delft, Architecture and the Built Environment

Faidra (Phaedra) Oikonomopoulou was born on 1984 in Athens, Greece. In 2009 she graduated with a diploma (MSc) of Architect Engineer from the Faculty of Architecture at the National Technical University of Athens [NTUA], ranking among the top students in her class. For the coming one year she worked both as an architect engineer in Athens and as a travel article contributor. In 2010 she followed a second master degree in Building Technology at the Delft University of Technology. It was her MSc thesis initiative that introduced her to glass as a structural material: "The design of a fully glass pavilion for the Temple of Apollo Epikourios in Peloponnese". She proudly presented the findings of her thesis in Challenging Glass 3 Conference. Following her graduation in 2012, Faidra embarked on an adventure in Namelok, a Maasai village in Kenya, to work on the use of mud bricks for construction and pursue her other big passions: travelling and wildlife spotting. Many elephants and lions later she returned to Delft as a researcher for a project on innovative glass joints, followed by a six-month internship in an engineering office specializing in structural glass applications in Athens.

In 2014 Faidra returned to Delft to work on a glass project that she knew little about: the Crystal Houses Façade. Faidra was the lead PhD researcher on the research and development of the applied adhesively bonded system. After approximately one and a half years of research and experimental work, together with colleague Telesilla Bristogianni they supervised the construction of the Crystal Houses façade and even built together with the construction crew the first 1.5 meter of the glass wall. For her work in the Crystal Houses Faidra has co-received multiple awards, including the Innovation Award 2016 by the Society of Façade Engineers and the Talent met Toekomst 2017. Through the Crystal Houses façade project Faidra discovered the architectural potential of cast glass, but also saw the engineering challenges involved. Together with Telesilla they have been awarded two 4TU. Bouw Lighthouse grants for innovative research on cast glass and their research on recycled cast glass building components was nominated for the New Material Award 2018.

Faidra pursued her PhD degree while working as a Researcher/Lecturer at the Architectural Engineering + Technology Department of the Faculty of Architecture at Delft University of Technology. Currently Faidra is employed as a Senior Researcher & Lecturer at the same department, where she continues her research on structural cast glass. Faidra has given invited talks and workshops on the structural potential of cast glass in several institutions, universities and companies in Europe and USA. Her vision is to create circular, load-bearing and aesthetically intriguing cast glass structures. Meanwhile she continues pursuing her other big passions as well, by travelling all over the world and encountering rare animals in the wild.