In this master’s thesis, the pressing need for novel, bio-based and fully circular construction materials is examined. Building on existing TU Delft research, the work focuses on cellulose and lignin as the principal constituents of a new wood-like composite, using waste streams as the source. The experimental setup, inspired by a range of studies on lignin-reinforced materials, employs a hot-pressing procedure. The literature review highlights a clear gap: the combined use of cellulose and lignin, each derived from by-products, to form an innovative material matrix, with the goal to make use of lignins adhesive qualities.
The methodology includes an innovative computational method designed to provide controlled variability of structural properties, that can be directly integrated into a component design. Many material variations, like moisture content, lignin types, C/L-ratio, pre-treatment and recyclability have been explored. Principal findings from this study include identifying optimal cellulose-to-lignin (C/L) ratios for distinct mechanical performances—3:2 for flexural strength and 2:3 for compressive strength. Additionally, Soda lignin shows the best mechanical performance and the plates can be successfully reprocessed. Computational simulations using Rhino 8, Karamba3D and Wallacei proved effective in predicting and optimising mechanical properties, significantly streamlining material development. Multidimensional scaling was used to map high-dimensional material data into a two-dimensional space, clustering formulations by performance and revealing trade-offs (e.g., stiffness vs. toughness) to guide blend selection.
Microscopic analyses further supported the viability of lignin as a natural adhesive, while highlighting areas needing improvement, such as brittleness and susceptibility to warping and blistering. A link was established between mechanical testing data and component modelling, which opens up possibilities to optimise both design and material composition for sustainable and resource efficient structures.
Overall, this research successfully demonstrates the potential of fully circular waste-based cellulose-lignin composites and paves the way for scalable, high-performance, sustainable building materials.