RE-FACADE GLASS PANELS: made by Construction & Demolition Recycled Glass

Abstract

Although glass is a known material for centuries, extensive usage and today’s technology –with modern construction methods– made glass one of the most valuable materials of the present and future. Witnessing an immense progression and a broad innovative boost in the construction field, creating the perfect link between indoor and outdoor environments.

Given the growth of the world’s population and its constant need to improve the way of living, the demand for new flat glass production, and the replacement of the older ones are rising. However, what is happening at the end-of-life of such architectural glass waste coming from the construction and demolition sector? Α significant amount of post-consumer flat glass waste is generated, which is either down-cycled into low-value applications or discarded at the end of the life cycle, aggravating the existing problem of glass recycling whilst resulting in a significant impact on the ecological footprint.

Glass is a readily recyclable material, that can be remelted and reformed indefinitely into articles with the same quality and properties as the original one, nominating it as a perfect candidate in the transition efforts for a low-carbon environment. Even though the glass packaging industry is a successful recycling market, the same is not true for the floating glass industry, which occupies a more complex position. The vast majority of the remaining waste is rarely recycled into the same product, due to the lack of an organized recycling scheme, the incompatibility of different glass recipes, and the contamination rates of glazed products that could lead to risks in the total production line.

Among the down-recycled or landfilled glass, there is a great proportion of high-value float glass, pointing out the large potential in upgrading the glass recycling process from a linear chain to a circular one. The main scientific contribution of this research is the development and experimental verification with the aim of casting technique, not only new design concepts and engineering their fabrication following the design criteria, but also an ideal recycling collection system for cullets coming from the C&D sector while utilizing tools to check the product’s performance and assessing its life cycle impact to the environment.

The casting method, as a more flexible process, that easily shifts between different recipes, and is less energy-intensive than float line, proves feasible for the fabrication of 100% recycled panels out of post-consumer flat glass waste. These findings are introduced by means of closed-loop alternatives that extend their service life, establishing at the same time the foundation for a circular life-cycle of architectural glass, while can assist as guidelines for further exploration. These components are monolithic elements with higher thickness, compared to the conventional thin-walled glass to tolerate a higher contamination rate, intended for building envelope applications. Their format is adopted and explored through a strategic approach of a translucent composite product, which is made out of specific glass waste layering arrangement between different purity grades of cullet in such a manner to form an advantage tensile strength on the recycled panel, which is transferred on the surfaces and reinforces the object.

Grasping the boundaries of glass recycling, which has been continuously stretching, in the last years, only some primary attempts have been made by TU Delft. These are referred on the fabrication of 3-dimensional strong glass components or glass panels emphasizing the aesthetic result always with the method of casting, unveiling the ambitious potential of glass upcycling for the building sector.

Identifying the scientific gap, the focus of this research is the proper mapping of the current situation of glass recycling, and the identification of the most promising glass C&D waste through experimental research by contacting melting and tools that have not been utilized before. The experimental analysis of the new concept concentrates on the development of the composite panel and the thermal shock testing in uneven temperatures, as the strength of recycled glass has already been investigated previously. Additionally, this concept will be assessed for further analysis and understanding of the whole effectiveness of the proposed supply chain of this recycling method, which is carried out for the first time.

The development of the new composite panel and its experimental evaluation displayed strong findings for further exploration. This thesis set-up could be a promising strategy for float glass recyclability but also in this product’s performance, for transcending the main barriers of flat glass refusal owing to either impurities or different glass synthesis, while it is aligned with the 2050 Dutch policy of zero waste in the construction field and the European guidelines linked to the sustainable movement. Recovering discarded glass in cast glass products opens new paths to reintroduce such waste back to the supply chain, as a closed-loop approach.