A Review of Shrinkage and Restrained Shrinkage Cracking in 3D Concrete Printing (2025-06)¶

The benefits related to the use of 3-dimensional concrete printing (3DCP) have been recognized worldwide. Key advantages include cost and time-related reductions in addition to reduced labour and maintenance requirements. However, due to this technology's novelty, many challenges must be addressed before it can be fully integrated into the construction industry. This paper reviews the phenomenon of shrinkage and the consequent shrinkage cracking. Due to the low volume of aggregates, hence high paste and fines content, and early exposure, 3D printed concrete (3DPC) is more likely to experience large shrinkage strains in comparison to cast concrete, to an extent where elements are at risk of cracking. Other factors, like early exposure, excessive plastic shrinkage and curing regimes also contribute to cracking. The reviewed literature shows that reported shrinkage strains of 3DCP elements are significantly larger than those of cast concrete. In addition, environmental and curing conditions, mix proportions, admixtures and specimen sizes have been found to influence the rate and magnitude of shrinkage. Variance in shrinkage strains between studies is partially attributed to the varying open time definition and difference between shrinkage measurement methods. This paper concludes that a standardized testing method should be developed to measure plastic and drying shrinkage for 3DCP elements to enable readers to easily compare the reported shrinkage strains from respective authors and develop a shrinkage database to identify governing factors and design guidelines.