Critical Review of Self-Healing Mechanisms in 3D-Printed Concrete (2026-03)¶

Three-dimensional concrete printing (3DCP) offers significant advantages for automated construction; however, persistent challenges such as microcracking, poor interlayer adhesion, and accelerated material degradation limit its long-term durability. This review addresses the central question of how self-healing technologies can be effectively integrated into 3DCP systems to improve structural performance and sustainability. Four healing strategies—autogenous, mineral admixture-based, microbial, and polymeric—are systematically analyzed within the constraints of extrusion-based digital fabrication. The novelty of this review lies in its focus on the intersection between self-healing mechanisms and the specific process requirements of 3DCP, an area that has not yet been fully synthesized in the literature. The analysis indicates that bacteriogenic calcite precipitation shows strong potential for field applications, while hybrid healing systems combined with embedded smart sensors may enable adaptive, self-monitoring structures. Nevertheless, several critical challenges remain, including the rheological compatibility of healing agents with printable mixtures, reliable activation under realistic service conditions, and the lack of standardized testing protocols. Addressing these challenges through multidisciplinary collaboration could significantly reduce maintenance requirements and improve environmental performance during the life-cycle of 3D-printed concrete infrastructure.