A systematic review of the fabrication and mechanical properties of 3D-printed composite clay bricks

This review investigates recent developments in 3D-printed composite clay bricks, with a particular focus on material innovation, geometric refinement, and mechanical performance. A systematic review supported by bibliometric analysis of seventy peer-reviewed publications from 2015 to 2025 was conducted, with findings further explored through thematic mapping using VOSviewer. Three major research clusters emerged, namely additive manufacturing processes, composite material enhancement, and environmental integration. Bio-based fibres, waste-derived fillers, and polymeric reinforcement were found to contribute significantly to improving strength, ductility, thermal behaviour, and printability, while geometric strategies such as triply periodic minimal surfaces and porous infill configurations enhance airflow, thermal regulation, and structural performance, enabling expressive architectural forms. Functional additives including foaming agents and nanomaterials demonstrated notable reductions in thermal conductivity, confirming the potential of composite clay systems for thermally performative construction applications. The field nonetheless faces important gaps, particularly the limited availability of life-cycle assessments, the absence of full-scale structural validation, and the separation of material and geometric investigations across the reviewed literature. In response, the review highlights the need for predictive modelling, standardised testing, waste valorisation pathways, and integrated material-geometry frameworks to support the wider adoption of 3D-printed composite clay bricks in sustainable construction.