3D打印混凝土各向异性力学性能研究

近年来,混凝土3D打印技术在土木建筑等领域取得了快速的发展和应用。与模板浇筑工艺不同,3D打印在逐行逐层堆叠的建造过程中引入了一定量的层间弱面和空隙,造成了细观非均质性;而且3D打印过程无法自动嵌入钢筋,制备纤维混凝土作为打印材料可有效改善力学性能。本文首先制备了一种适用于挤出型3D打印工艺的玄武岩纤维增强陶砂混凝土,将水平打印层作为XY平面,然后从三个正交方向加载,实验测试了3D打印混凝土的抗压、抗弯等力学性能,提出了各向异性系数及其评估方法。研究结果表明,对于单轴压缩,X方向强度最高,而对于抗弯性能,Y方向强度最高。纤维对挤出型3D打印材料的各向异性影响较大,纤维掺量越大,各向异性越大。

Experimental study on the mechanical anisotropy of 3D printed concrete

In recent years,concrete 3 D printing technology has achieved rapid development and application in the field of civil construction.Different from mould casting process,the layer-by-layer process of 3 D printing inevitably introduces a number of regular weak interfaces and voids into the materials,resulting in certain heterogeneity.The steel bars cannot be inserted in 3 D printing process,while the printable fiber reinforced concrete can effectively improve the mechanical properties.In this paper,a new kind of basalt fiber reinforced ceramic sand concrete is firstly prepared for the extrusion-type 3 D printing process.Then taking the horizontal printing layers as the XY plane,the samples are loaded from three orthogonal directions to measure the compressive and flexural mechanical properties of prepared concrete.In particular,an anisotropic coefficient was given to evaluate the mechanical anisotropy.The results show that the printed specimen performs the best uniaxial compression capacity when loaded from X direction,while when exposed to Y direction loading,the specimen exhibits the highest bending resistance.