LIGNISLAB

Abstract

The construction sector’s transition toward a circular, low-carbon built environment demands a fundamental rethinking of structural systems. Floors account for up to 40% of a building’s embodied carbon, yet conventional floor systems are designed without consideration for material recovery or reuse. This thesis develops a conceptual modular floor system from a hot-pressed
fibre biocomposite, addressing both embodied carbon reduction and circular construction through design for disassembly.

The research combines a theoretical framework, experimental material characterisation, design development and structural verification. The theoretical framework establishes three pillars: An analysis of conventional floor systems revealing proven structural principles and a persistent trade-off between structural and environmental performance, an exploration of biocomposites as a promising structural direction, and the principles that enable modularity. A lignin-bound pine fibre biocomposite developed by Lignitec is selected and mechanically tested, revealing exceptional compressive strength alongside
limited tensile capacity. Together, the framework and test results inform a no-tension design strategy in which prestressing keeps the entire cross-section in compression, allowing discrete modules to collectively form a spanning element without bonded connections.

The resulting system consists of ribbed, hot-pressed modules assembled through prestressing into a coherent spanning element. This design was developed across three scales: module, spanning element and floor system allowing a fully integrated design. A 1:5 scale prototype confirmed both the producibility of the concept and the validity of the analytical calculations. The results demonstrate that a structurally viable, fully biobased and demountable floor system is achievable, though further research and development are necessary before the system can reach practical application.