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Binder jetting 3D printing rock analogs using magnesium phosphate cement
Abstract Fractures in rocks have significant effects on the stability of rock mass structures. Physical model testing is an effective approach for investigating the failure mechanisms of fractured rocks. In this paper, a new binder jetting (BJ) 3D printing technology using magnesium phosphate cement (MPC) is proposed to fabricate rock models with isotropic and brittle matrices and complex fractures. A self-developed BJ 3D printer is used to perform the printing and investigate the effects of different layer thicknesses, molar ratios of magnesium oxide to phosphate (M/P), and borax retarder contents on dimensional accuracy, mechanical anisotropy, and brittleness. The test results show that the layer thickness and M/P exert significant influences on the dimensional accuracy and mechanical anisotropy by regulating the binder’s diffusion and penetration into the powders. The degree of hydration, and thus the brittleness of the specimens, is also influenced by different M/P values. The borax retarder prolongs the setting time, and thus provides a longer hydration time, resulting in better interlayer bonding and lower mechanical anisotropy. The optimized specimens exhibit a much lower anisotropy index in compressive strength compared to that of the counterpart commercial sand and gypsum BJ printed specimens, and the high brittleness index of the 3D printed specimens indicates it can achieve the rating of brittle rocks. The crack initiation angles and failure patterns of printed specimens with single and double fractures are consistent with those of practical rock specimens, which demonstrates that the proposed BJ 3D printing method using MPC is promising for reproducing highly accurate rock-like models with complex fractures.
Highlights Binder jetting 3D printer for MPC cement is developed. Accuracy, anisotropy and brittleness are optimized to fabricate rock-like models. Binder jetting 3D printing using MPC cement is feasible to fabricate rock analogs.
Binder jetting 3D printing rock analogs using magnesium phosphate cement
Abstract Fractures in rocks have significant effects on the stability of rock mass structures. Physical model testing is an effective approach for investigating the failure mechanisms of fractured rocks. In this paper, a new binder jetting (BJ) 3D printing technology using magnesium phosphate cement (MPC) is proposed to fabricate rock models with isotropic and brittle matrices and complex fractures. A self-developed BJ 3D printer is used to perform the printing and investigate the effects of different layer thicknesses, molar ratios of magnesium oxide to phosphate (M/P), and borax retarder contents on dimensional accuracy, mechanical anisotropy, and brittleness. The test results show that the layer thickness and M/P exert significant influences on the dimensional accuracy and mechanical anisotropy by regulating the binder’s diffusion and penetration into the powders. The degree of hydration, and thus the brittleness of the specimens, is also influenced by different M/P values. The borax retarder prolongs the setting time, and thus provides a longer hydration time, resulting in better interlayer bonding and lower mechanical anisotropy. The optimized specimens exhibit a much lower anisotropy index in compressive strength compared to that of the counterpart commercial sand and gypsum BJ printed specimens, and the high brittleness index of the 3D printed specimens indicates it can achieve the rating of brittle rocks. The crack initiation angles and failure patterns of printed specimens with single and double fractures are consistent with those of practical rock specimens, which demonstrates that the proposed BJ 3D printing method using MPC is promising for reproducing highly accurate rock-like models with complex fractures.
Highlights Binder jetting 3D printer for MPC cement is developed. Accuracy, anisotropy and brittleness are optimized to fabricate rock-like models. Binder jetting 3D printing using MPC cement is feasible to fabricate rock analogs.
Binder jetting 3D printing rock analogs using magnesium phosphate cement
Ma, Guowei (author) / Hu, Tingyu (author) / Li, Zhijian (author)
2024-02-25
Article (Journal)
Electronic Resource
English
| European Patent Office | 2023
| European Patent Office | 2024