Earth as a Building Material: From Traditional Building Techniques to Additive Manufacturing

The research interest for earth-based building materials has increased extremely in recent years because of a tremendous rise of housing-demand worldwide, together with the necessity of fostering environmentally friendly solutions within the construction industry. Nevertheless, the diffusion of earthen construction is still limited due to many reasons among which it is worth mentioning the poor durability of these materials (e.g., their sensitivity to moisture) and the lack of Codes and regulation for their design. In the meanwhile, new construction methods disrupt the market, among them, additive manufacturing (AM) has demonstrated its potential to transform the construction industry, especially through the 3D printing technology by extrusion. This technique has been widely studied for concrete production but only recently has been applied for earth-based materials, being only validated under laboratory conditions with few real-scale applications. In this chapter, a review on earth-based materials for the building industry is presented, paying attention to the characteristics needed by these materials to be suitably applied in modern AM processes. Advantages, current limits and open challenges in 3D printing such geomaterials will be presented. Lastly, some case studies will be shown.