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Natural earth-fiber building assemblies such as light straw clay, hempcrete, and clay-plastered straw bales incorporate vegetable by-products that are mixed with geological binders, traditionally used as an insulative infill in building construction. As a geo- and bio-based insulative infill method composed mostly of fiber, heat transfer coefficients are lower than mass materials, making it a compatible assembly that meets energy code requirements. Furthermore, due to their permeability, these materials exhibit high hygric capacity, providing regulated indoor temperatures and relative humidity levels, thus showing a promising future for socially just and healthier built environments. Despite these advantages, the use of earth-fiber building materials in digital construction is still underdeveloped. In the past few years, 3D-printed earth has gained an increasing interest, however, high contents of fibers in earth mixtures have yet to be fully tested and characterized. This paper presents an experimental workflow to characterize fiber-earth composites for 3D printed assemblies, using natural soils infused with natural fibers. The paper begins with a literature review of a range of fibers: straw, hemp, kenaf, sisal, and banana leaves, as well as naturally occurring biopolymer additives. The experimental setup includes manual extrudability and buildability tests, to identify optimal mix designs that are then tested for their printability and buckling using clay 3D printers. As a final deliverable, first pass geometric studies showcase the lightweight and structural possibilities of each material. The significance of this research lies in the development of a methodology for identifying novel mix design for digital fabrication, by increasing carbon storing vegetable fiber content within digital earth, and by creating a range of natural 3D printed assembly types: from mass-insulation walls to paper-thin lightweight partition assemblage. 

With a growing interest in sustainable construction practices and recent advances in the field of digital fabrication, 3D-printed earth has gained significant interest. However, research in 3D printed earth remains limited to cob, thus resulting in low thermal conductivity. Maximizing fiber content can provide greater thermal resistivity, while increasing carbon storage. This paper presents the development of 3D printed earth-fiber composite with fiber content ranging from commonplace cob (2% fiber) to newly developed printed light straw clay (64% fiber). This work contributes to critically needed advancements and framework for the development of low-carbon and high-performance materials for digital fabrication. 

Development of construction and materials standards serve technical, social and economic objectives. Most significantly, standards are required for the acceptance of materials by the engineering community. This paper contrasts the characteristics of codes and standards, and their development, for engineered materials and those for nonconventional and vernacular materials. Challenges associated with code and standard development for these materials are highlighted and discussed through case studies. Recommendations for approaches to codes and standards development for nonconventional and vernacular materials are presented.