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Investigation of steel wire mesh reinforcement method for 3D concrete printing

Liu Miao, Zhang Qiyun, Tan Zhendong, Wang Li, Li Zhijian, Ma Guowei

Archives of Civil and Mechanical Engineering

2021

Vol. 21, no. 1

406--423

3D concrete printing has received widespread attention and been developed for an increasing number of applications. However, a major challenge facing this technology is an effective way to introduce reinforcement into continuously deposited cementitious material. In this study, different layers of steel wire meshes (SWM) are employed to reinforce the 3D printed structures to improve mechanical capacities. Both destructive (bending, compression and splitting) and non-destructive (using electro-mechanical impedance) tests are employed to characterize the impact of this reinforcement method. The damage accumulation process is measured through the smart PZT patches based on the electro-mechanical impedance method. The results indicate that reinforced 3D-printed components with SWM change their failure modes from brittle to ductile. The peak loads are increased by 59.2–173.3% and the deflection capacity can be increased by more than 11 times than the non-reinforced one. Different mechanical responses of print and cast samples under compression are studied. The splitting tensile strength of wire mesh reinforced concrete is also measured, which is 43.7% higher than the non-reinforced sample. The calculating methods of the cracking moment and ultimate moment of steel wire mesh reinforced 3D printed concrete are presented. Comparison between the calculated and the experimental results verifies the effectiveness in predicting the ultimate moment. Experimental results show that it is feasible and effective to employ steel wire mesh for strength and toughness enhancement of 3D printed structures.

Mechanical behaviors of 3D printed lightweight concrete structure with hollow section

Wang Li, Jiang Hailong, Li Zhijian, Ma Guowei

Archives of Civil and Mechanical Engineering

2020

Vol. 20, no. 1

219--235

A practical revolution in construction could be realized by combining the potential of 3D concrete printing with lightweight cementitious materials to fabricate adeptly hollow structures. In this study, five concrete mixtures with different replacement rates of lightweight ceramsite sand to silica sand are prepared for extrusion-based 3D printability evaluation. To reduce the water absorption induced shrinkage and micro-cracks, the ceramsite sands were coated with polyvinyl alcohol. An optimized cementitious material was identified by harmonizing the fresh properties to the continuous printing process. Cubic and beam elements with four different types of interior hollow structures were designed and 3D printed based on the optimized lightweight mixture. The interior structures include cellular-shaped structure, truss-like structure, lattice-shaped structure with a square topology, as well as gridding shaped structure with triangle topology. The mechanical capacities of the printed samples were measured and evaluated by compressive tests for the cubic samples and four-points flexural bending tests for the beam specimens. Basing on the results, the rectangular lattice hollow structure demonstrates the best mechanical resistance to compression and the truss-shaped prism structure ensues the highest flexural properties. The stress distribution and failure process were also explored through discrete element method.