Comprehensive Investigations on the Relationship Between the 3D Concrete Printing Failure Criterion and Properties of Fresh-State Cementitious Materials (2023-09)¶

In the 3D concrete printing (3DCP) process, the fresh-state cementitious material is extruded layer by layer without any formwork support; hence, high buildability is required to resist printing failure. Although the printing failure is considered correlated to the strengths and elastic moduli of fresh 3DCP materials, the quantitative relationship between the 3DCP failure criterion and material properties is unclear. In this study, constant shear rate tests (CSRTs), large amplitude oscillatory tests (LAOTs), unconfined uniaxial compression tests (UUCTs), and squeeze flow tests (SFTs) were conducted to determine the properties of three 3DCP mixtures. By analyzing different test methods, this paper found that the Mohr-Coulomb failure criterion can be determined by combining CSRT and UUCT results, and the elastic modulus transmitted from the shear modulus of LAOT is not comparable to those from UUCT and SFT. By analyzing the stress states of the 3DCP member and tested samples, this paper revealed that during printing, the critical areas in the 3DCP member are uniaxially and biaxially compressed with the same compressive strength. Since UUCT results represent compressive performances of uniaxially compressed areas, the 3DCP failure criterion can be determined by UUCT without combining other testing methods. Furthermore, the prediction from UUCTs presented a good fit compared to printing test results with an error of 3.56%; thus, the quantitative link between the 3DCP failure criterion and material compressive strengths from UUCTs was validated.