Shrinkage in Concrete Additive Manufacturing (2026-02)¶

Shrinkage-induced cracking, driven by high cementitious content and layer-by-layer fabrication, poses a significant challenge to the volumetric stability and large-scale application of 3D printed concrete (3DPC). This paper systematically and critically reviews recent advances in 3DPC shrinkage by deconstructing the complex interplay among materials, processes, and environmental factors governing its mechanisms, characterization, and control. The analysis reveals that shrinkage in 3DPC arises from coupled plastic, autogenous, and drying mechanisms. Crucially, the review identifies that the anisotropic and highly connected pore network at filament interfaces acts as a key driver of accelerated moisture transport and stress inhomogeneity, and representing a distinctive microstructural feature of 3DPC compared with conventional cast concrete. Current characterization methodologies are limited, as conventional tests fail to capture this layered anisotropy, and a unified standard remains absent. While mitigation strategies based on material design, curing, and structural optimization show promise, a systematic framework is lacking. By identifying critical research gaps, this review establishes a foundation for developing integrated control strategies, thereby advancing the long-term durability of 3DPC structures.