Beyond the Bond

Abstract

Segmented cast-glass assemblies show high potential for transparent, compression-dominated architectural structures, but their reliance on permanent bonding methods currently limits disassembly, reuse, and closed-loop recycling. Directly 3D-printing polymer interlayers onto glass components offers a promising route toward mechanically interlocked, adhesive-free connections. However, the resulting glass–polymer adhesion, thermal stability, interlocking geometry, structural performance, and end-of-life removability require further investigation. This research therefore aims to optimise the material behaviour and geometric interlocking design of an additively manufactured polymer interlayer to achieve reversible and structurally reliable dry-fit connections between planar cast-glass units.

The study followed an iterative research-through-design methodology combining literature review, material screening, geometric development, vault-scale design application, mechanical validation, and demountability testing. Six FDM polymers were directly printed onto glass to evaluate adhesion reliability, thermal behaviour, and substrate recovery. Simultaneously, interlocking typologies were evaluated to define a printable hybrid geometry. For mechanical validation, the three most promising materials were combined with four variants of the developed hybrid interlocking typology, resulting in twelve glass–interlayer–glass specimens tested under combined normal and shear loading.

The material experiments identified reinforced PET-based polymers as the most viable direction, with PETG-CF providing the most favourable balance between adhesion, dimensional stability, print quality, and damage limitation. The final geometry combined distributed surface-based engagement with a removable-key locking mechanism, transferring shear forces through mechanical interlocking rather than permanent bonding. The demountable vault case study established a design shear demand of 1.10 kN per full interlayer. PETG-CF specimens significantly exceeded this demand; the two final geometries both showed utilisation factors below 0.19, with one providing the highest mechanical performance and the other offering the best balance between shear capacity, non-destructive removal, and material recovery.

This research demonstrates that a directly printed, mechanically interlocking polymer interlayer can provide a structurally effective and reversible connection strategy for planar cast-glass components. Thereby, it advances cast-glass construction beyond permanent bonding towards a validated proof-of-concept for adaptable, demountable, and circular structural glass assemblies.