Influences of Air-Voids on the Performance of 3D Printing Cementitious Materials.

Yujun Che,Weiwei Li,Shengwen Tang,Huashan Yang,Mengyuan Shi

doi:10.3390/ma14164438

Abstract

This paper focuses on inspecting the influences of anti-foaming agent (AFA) on the performance of 3D printing cementitious materials (3DPC). The mini-slump, spreading diameter, yield stress, and strength of 3DPC were evaluated. Additionally, the air-void content, air-void morphology, and air-void size distribution of mortar with and without 0.05% AFA were assessed through image analysis. The mechanical performance and air-void structure of 3D printed samples were also investigated and compared to that of conventionally mould cast samples. Test results show that an optimal AFA content enables 3DPC to achieve favorable workability and mechanical performance. The addition of AFA exhibits lower air-void content in 3DPC than that of the sample without the AFA addition. This reduction in air-void content is further strengthened by the results of strength analysis. Electron microscope analysis shows that the use of AFA results in the suppressed formation of large air-voids during the process of fresh 3DPC. Moreover, the air-void morphology substantially influenced the mechanical performance of hardened 3DPC.

Highlights

When considering 3D printing concrete technology, an extrusion-based additive construction technique [1] could be used to build complex construction structures layer-bylayer due to its rapid prototyping
While the advantages of 3D printing cementitious materials (3DPC) have been studied by many researchers [10,11,12,13,14], advanced 3DPC is still under development with various restrictions, such as unreliable manufacturing processes, weak joints, low mechanical strength, and anisotropic performance in recent literatures [15,16,17]. One such obstacle is unavoidable weak joints between printed layers compared with mould cast cementitious materials, which are the weakest links in 3DPC [18,19]
anti-foaming agent (AFA) achieved 4.1–34.0% and 45.6–67.9% at 7 and 28 days, respectively. These results indicate that AFA can significantly improve the flexural and compressive strength of 3DPC, which can be attributed to the decrease of the air-void content, as discussed later

Summary

Introduction

When considering 3D printing concrete technology, an extrusion-based additive construction technique [1] could be used to build complex construction structures layer-bylayer due to its rapid prototyping. While the advantages of 3D printing cementitious materials (3DPC) have been studied by many researchers [10,11,12,13,14], advanced 3DPC is still under development with various restrictions, such as unreliable manufacturing processes, weak joints, low mechanical strength, and anisotropic performance in recent literatures [15,16,17]. One such obstacle is unavoidable weak joints between printed layers compared with mould cast cementitious materials, which are the weakest links in 3DPC [18,19]. A comprehensive understanding of the air-void structure is required to enhance the performance of a particular mix

Methods

Results

Conclusion