Development of CO2-activated interface enhancer to improve the interlayer properties of 3D-printed concrete

• Published in: Cement & concrete composites Vol. 162; p. 106122
• Main Authors: Lucen, Hao, Hanxiong, Lyu, Huanghua, Zhang, Shipeng, Zhang, Jianzhuang, Xiao, Sun, Poon Chi
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2025
• Subjects: CO2-Activated interface enhancer; Dicalcium silicate; Interlayer strength; Microstructure; Pore characteristics; Dicalcium silicate; Interlayer strength; Microstructure; CO2-Activated interface enhancer; Pore characteristics
• ISSN: 0958-9465
• DOI: 10.1016/j.cemconcomp.2025.106122

This paper presents an approach to enhance the interlayer properties of 3D-printed concrete (3DPC) by synchronously spraying CO2-activated interface enhancer (CIE) onto the surface of printed concrete filament during the printing process, thus overcoming the inherent limitation of weak interlayer properties and unlocking new possibilities for automation construction. The CIE was developed by using dicalcium silicate (C2S), a binder mineral with high carbonation activity. It was found that applying a 100 μm thick CIE resulted in a remarkable enhancement ratio of 249.3 % in the interlayer strength of 3DPC at 28 days. Subjected carbonation, CIE produced calcium carbonates and silica gel, which effectively filled the interlayer microstructure, leading to a reduced porosity. Furthermore, the activation of the CIE led to the growth of spear-like calcium carbonate crystals and rod-like ettringite crystals, which played a crucial role in enhancing the bonding performance by forming an interlocking microstructure. Contrary to common belief, a prolonged printing interval was beneficial for CIE, as it allowed for increased CO2 penetration, thereby enhancing the carbonation degree. In conclusion, the CIE developed in this study can be considered a promising approach for enhancing the interlayer properties of 3DPC. •The C2S -rich CO2-activated interface enhancer (CIE) is developed.•The transformation of printer head can realize the synchronous spraying of CIE.•A thickness of 100 μm CIE leads to a 249.3 % enhancement ratio of interlayer strength.•The CIE induces a transformation in the microstructure of the interlayer within 3DPC.•The printing interval time has a positive impact on the effectiveness of the CIE.