Search for: All records

Natural building materials like clay soils and plant fibres are undergoing a renaissance in ecological design and architecture. Nonetheless, design creativity and fabrication using natural materials have mostly relied on manual techniques, such as cob and rammed earth, which are limited to heavy mass assemblies in rectilinear geometries with thick straight lines. Introducing digital fabrication with diverse ranges of processing parameters to natural materials can introduce novel patterns, textures, geometries and performances. This study explores the integration of 3D printing with soil- and plant-based fibre material recipes with high fibre content, culminating in digitally designed vessels inspired by traditional basketry protocols. Computational models of basket ‘wall’ profile typologies, from vertical to convex and concave geometries, were evaluated for their resulting printed patterns and structural stability. The texture results achieved in this work aim to challenge the digital aesthetics dominated by petroleum-based or thermoplastic pastes. Distinct printing qualities and pattern resolution were shown to be achieved for different fibre types, from wheat straw to longer hemp and banana fibres. By leveraging digital tools to reimagine ancient materials and techniques, this research aims to foster a deeper connection between constructed forms and our relationship with soil and plants as essential stewardships required for environmental agency in creative and accessible design. Exhibited in several design venues, the resulting artefacts showcase novel fusions of material surface patterns, crafted through machine deposition, embodying traditional inspirations in sustainable digital design. 

Driven by the need for sustainable construction solutions, there is renewed interest in earth-based materials. Biopolymer stabilizers can enhance the rheological and structural properties of these materials to facilitate their use in 3D printing. This research examined the influence of sodium alginate on the stability, particle interaction, rheology, and 3D printability of kaolinite, a commonly found clay in soils deemed suitable for construction. Findings revealed that sodium alginate could boost electrostatic interactions to enhance the stability of kaolinite suspensions. This rise in repulsive potential energy could reduce storage modulus and yield stress by orders of magnitude. However, as the alginate content increased beyond its critical overlapping concentration (0.12 %–0.6 %), a reverse trend was observed, which was attributed to the formation of a three-dimensional polymer network. Furthermore, alginate addition shifted the “printability window” of kaolinite mixtures to higher solid contents, which has positive implications on the strength and shrinkage of the printable mixtures. 

Earthen building materials are experiencing a renaissance in light of the climate crisis. To engineer high-performance sustainable and durable earthen materials for the 21st century, the importance of chemistry—and biology—cannot be underestimated. 

Sustainable earthen building materials provide a pathway to mitigating the environmental impacts of the modern construction sector. While the application of these materials has been limited due to the inherent heterogeneity, erosivity, and weak mechanical properties of soil, the physical and thermal properties can be improved through the addition of ubiquitous, non-toxic, sustainable biopolymers. Yet, the fundamental understanding of the physiochemical bonding mechanisms between clays and biopolymers in this system is limited. In this work, a ‘micro to macro’ methodological approach was applied to investigate the bonding characteristics of common clays and clay-stabilizing biopolymers. At the micro-scale, fundamental interactions of clays (i.e., kaolinite, bentonite) with biopolymer additives (i.e., xanthan gum, guar gum, sodium alginate, microcrystalline cellulose) were assessed through mineral binding characterization techniques, including Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The findings were used to interpret unconfined compressive strength (UCS) tests results for macro-scale soil-biopolymer composites samples (1% biopolymer by soil mass). The results from this study illustrate the utility of understanding the mechanisms of clay-biopolymer interactions for improving the design of strong and durable earthen materials and structures.