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Concrete 3D printing of lightweight elements using hollow-core extrusion of filaments
Cement & Concrete Composites ( IF 10.5 ) Pub Date : 2021-08-11 , DOI: 10.1016/j.cemconcomp.2021.104220
Sayanthan Ramakrishnan 1 , Shravan Muthukrishnan 1 , Jay Sanjayan 1 , Kirubajiny Pasupathy 1
Affiliation  

This paper assesses the feasibility of 3D concrete printing of lightweight elements by the extrusion of hollow-core filaments. Two different filament shapes of rectangular hollow shape and U-shape were printed by using customised print nozzles. The primary challenge in hollow-core 3D printing is the extrudability and the stability of the overhang of the filament at fresh state. The stability of the overhang was assessed by determining the viscosity recovery rate and yield strength growth rate of the mix with nanoclay as a thixotropic additive. The mix containing 0.2 wt% of nanoclay has shown good extrudability and enhanced stability of the overhang. The hollow-core 3D printed elements have shown a reduced density of 1369.6 kg/m3 and 1701.7 kg/m3, compared to 2114.1 kg/m3 obtained for solid-core printing. The compressive strength and the Modulus of Rupture (MoR) of hollow-core filaments evaluated at different directions reveal a significant strength loss in perpendicular and lateral directions due to the effective bond area reduction between filaments. The thermal performance of 3D printed panels assessed using simulated test room experiments reports that the hollow-core panels have high thermal inertia due to increased insulation capacity. However, the lack of thermal energy storage has resulted in high indoor temperature in these test rooms.



中文翻译:

使用空心长丝挤出的轻质元件的混凝土 3D 打印

本文评估了通过挤压空心细丝来 3D 打印混凝土轻质构件的可行性。使用定制的打印喷嘴打印矩形空心和 U 形两种不同的长丝形状。空心 3D 打印的主要挑战是新鲜状态下长丝悬垂的可挤出性和稳定性。通过确定具有纳米粘土作为触变添加剂的混合物的粘度恢复率和屈服强度增长率来评估悬垂的稳定性。含有 0.2 wt% 纳米粘土的混合物显示出良好的可挤出性和增强的悬垂稳定性。与 2114.1 kg/m 3相比,空心 3D 打印元件的密度降低了 1369.6 kg/m 3和1701.7 kg/m 3获得用于实芯印刷。在不同方向评估的空心长丝的压缩强度和断裂模量 (MoR) 表明,由于长丝之间的有效粘合面积减少,垂直和横向方向的强度损失显着。使用模拟测试室实验评估的 3D 打印面板的热性能表明,由于绝缘能力增加,空心面板具有高热惯性。然而,热能储存的缺乏导致这些测试室的室内温度很高。

更新日期:2021-08-12
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