Material –Geometry–Process Integration in Printing Clay-Based TPMS Porous Structures

Additive manufacturing of clay-based materials offers a sustainable route to fabricate efficient building components, yet printing highly viscous pastes into complex, porous geometries remains challenging. This study presents a comprehensive workflow that integrates material formulation and printing strategies to assess and enhance the printability of porous clay structures. Tailored clay mixtures are developed to balance water content and implement a custom extrusion system alongside a parametric slicing environment. Functionally distinct porous structures, Triply Periodic Minimal Surface (TPMS), are designed with controlled porosity and subdivided (1/8, 1/4, 1/2) and graded (solid-to-porous) under systematically varied conditions. Finally, the printability of the porous structures is assessed through flowability, extrudability, and buildability. The results demonstrate that stable extrusion for clay pastes (Clay: Water=5:2) with balanced viscosity and plasticity, unsupported printing overhang angle limits up to 45°, dimensional discrepancy of approximately 1 mm in the build direction after printing, firing-induced shrinkage of 12.51~18.26%, and a relative height deviation (Δh/h₀) below 2.5%. These findings elucidate the critical interplay between viscous clay behavior and digital fabrication parameters, advancing reliable clay printing techniques and unlocking new possibilities for customized, resilient building elements in sustainable architecture.