3D打印混凝土的各向抗压性能研究

Research on anisotropic compressive properties of 3D printed concrete

3D打印混凝土构件受材料层层堆叠工艺的影响,其力学性能具有各向异性。参考C30普通混凝土配合比设计,设计制备了两批不同龄期的3D打印混凝土立方体试件和棱柱体试件进行抗压强度试验,分析三种不同加载方向下3D打印混凝土试件的破坏规律。进行了棱柱体试件X向轴心抗压强度与立方体试件立方体抗压强度的比较,测试了打印混凝土轴心抗压强度试验时棱柱体试件的弹性模量,并与国内外学者的混凝土弹性模量理论计算值进行对比。结果表明:14d龄期与28d龄期的试件在相同方向受压时其破坏模式类似;14d龄期试件抗压强度可达到28d龄期试件抗压强度的80%~90%;立方体试件X向加载下的抗压强度最高,Y向加载下的抗压强度最低;14d龄期混凝土弹性模量与Dhir的理论计算值最为接近,28d龄期弹性模量与规范ACI 318-19的理论计算值最为接近。

Affected by the layer-by-layer stacking process of materials, the mechanical properties of 3 D printed concrete specimens are anisotropic. Two groups of 3 D printed cube and prismatic concrete specimens with different curing ages were designed and printed with reference to the mixing proportion of C30 ordinary concrete to carry out the compressive strength tests, and the failure laws of 3 D printed concrete specimens under three different loading directions were analyzed. The axial compressive strength of the prismatic specimen in the X-direction was compared with the cubic compressive strength of cube specimens. The elastic modulus of the prismatic specimens during the axial compressive strength test of the printed concrete was also tested, which was compared with the theoretical calculation values proposed by domestic and foreign scholars. The results show that the failure modes of the specimens with 14 days age and 28 days age are similar when compressed in the same direction. The compressive strength of the specimens with 14 days age can reach 80%~90% of the compressive strength of the specimens with 28 days age. The compressive strength of the cube specimen under X-direction loading is the highest, and the compressive strength under Y-direction loading is the lowest. The elastic modulus of concrete with 14 days age is the closest to the theoretical calculation value of Dhir, while the elastic modulus with 28 days age is the closest to the theoretical calculation value of code ACI 318-19.