Early age time-dependent mechanical properties of 3D-printed concrete with coarse aggregates

• Published in: Construction & building materials 2024-11, Vol.451, p.138756, Article 138756
• Main Authors: Chen, Yidong, Zhang, Yunsheng, Quan, Hongzhu, Liu, Cheng, Liu, Zhiyong, Zhang, Yu, Chen, Mingxu, Wang, Liang, Wang, Zhiyong
• Format: Article
• Language: English
• Subjects: 3D concrete printing; Coarse aggregate; Digital Concrete; Early age properties; Structural stability
• ISSN: 0950-0618
• DOI: 10.1016/j.conbuildmat.2024.138756

Incorporating coarse aggregate into 3D-printed concrete is essential for promoting its practical application, yet the impact on the early age time-dependent mechanical properties, crucial for the multilayer structure stability and quality, is underexplored. In this study, 3D-printed concrete with coarse aggregate (3DPCA) with varying mortar-to-coarse aggregate ratios (M/A) and coarse aggregate gradations were prepared, of which uniaxial unconfined compression and direct shear performance were experimentally investigated. The fundamental formulations between the early age mechanical parameters and the resting time of 3DPCA were characterized and then utilized in a digital model simulating actual printing. Results indicated that the 3DPCA early age mechanical properties, including compressive strength, Young's modulus, cohesion, and friction angle, increased with longer resting time and decreasing M/A, and higher proportions of aggregates above 9.5 mm. High coarse aggregate content caused three distinct compressive strength-displacement curve stages and complicated strength eigenvalue extraction. Coarse aggregate gradation affected shear properties more than content, with larger aggregates improving cohesion and friction angles. The failure mode prediction model based on ABAQUS could accurately predict the maximum collapse layer of 3DPCA that occurred in overall unstable collapse and over-expansion failure but was incapable of localized deformation. [Display omitted] •Time-dependent mechanical parameters of 3DPCA within 60 min resting time are characterized.•The effect of coarse aggregate content and gradation on the 3DPCA properties are investigated.•A prediction digital model accurately predicts the maximum failure layer of the 3DPCA wall.