Recycled Sand for 3D-Printed Strain Hardening Cementitious Composite (2025-06)¶

3D printing of cementitious materials (3DPCM) has emerged as an innovative breakthrough, enabling the development of structures with complex geometries and faster construction. Additionally, if the raw materials for 3D printing are sourced from recycled materials, this digital construction technique has the potential to address the issue of construction and demolition waste buildup and reduce the over-extraction of natural resources. However, the inclusion of reinforcement remains as one of the distinct challenges of 3DPCM. The development of printable Strain Hardening Cementitious Composites (SHCC), also known as Engineered Cementitious Composites (ECC) has attracted the attention of both academia and industry as an approach to improve the tensile strength and ductility of 3DPCM. SHCC is characterized by controlled microcracking under uniaxial tensile loading and excellent ductility, achieved through the incorporation of short fibers as self-reinforcement. This article surveys the state of the art in current advancements, challenges, and opportunities related to the use of recycled sand for 3D-printable SHCC.