Development and evaluation of a functionally graded additive manufactured biocomposite envelope system

Abstract

The implementation of Additive Manufacturing (AM) in construction has been proposed as a viable alternative as it can help mitigate the environmental impact of the construction industry through material waste reduction, elimination of formwork and scaffolding, and quick building times; while also enabling the fabrication of environmentally, structurally and materially optimized geometry. Most AM technologies in construction use homogeneous cement-based mixes, which albeit efficient in material use are nevertheless energy-intensive; not entirely addressing the fundamental problem of cement’s widespread use and its high environmental impact. Incorporating sustainable materials into AM for construction is a way to address this issue and is currently at a research phase. This thesis proposes a biocomposite material consisting of cement, lime, clay and hemp to be used with AM through function-based material arrays. Fabricating composite envelopes that match specific functions to localized regions of the material, such as in Functionally Graded Materials (FGM), can meet performance requirements by integrating performative materials only at critical target regions, and substituting non-target areas with comparatively lower-Embodied Energy (EE) material components. The building system presented in this thesis furthers the concept of blurring edges between the various discrete materials and components comprising a conventional building assembly, merging them through a gradient transition into a multi-material, multi-purpose monolithic envelope unit to achieve useful and appropriate combinations of materials, generating minimal waste during the fabrication of environmentally, structurally, materially-optimized and customized buildings using low EE materials whose beneficial properties will allow for low Operational Energy (OE) consumption.