Sustainable raw-earth blocks achieved with 3D-printed formworks: parametric modeling, prototyping, and laboratory testing

The demand for green construction requires a fundamental shift in construction techniques and materials to prioritize sustainability. In this context, the present work introduces a modular building block crafted from raw-earth using innovative and accessible 3D-printed formworks. To achieve such an ambitious goal, it was necessary to i) create a parametric model, ii) produce the 3D-printed prototypes to investigate different formworks with various configurations, iii) and conduct an extensive series of laboratory tests to prove the performance of the component. The prototype is applied to the context of central Italy, utilizing materials sourced from the province of Chieti, specifically Casalincontrada, where earthen architecture has been utilized for centuries. Thanks to the capabilities of the combined parametric model and iterative testing procedures, it was possible to obtain an effective block with great flexibility in the application of both building components and furnishings. The results prove the feasibility of the innovative construction system using raw earth blocks achieved with 3D-printed formworks. Indeed, an efficient material configuration is identified as Gravel 5.5%, Sand 19.4%, Silt 46.1%, and Clay 29.0%, demonstrating an effective compression strength of 3.4 MPa ± 0.25 MPa and average linear shrinkage limited to 4%, sufficient to achieve a performing block.