Mechanical and microstructural properties of 3D-printed aluminate cement based composite exposed to elevated temperatures

Abstract

Investigation into the mechanical performances of 3D-printed composite exposed to elevated high-temperatures is of great significance for broadening the engineering application field of 3D printing. Aluminate cement-based composite was developed for 3D printing. The setting time, flowability, and printability of the composite material were adjusted by adding proper dosages of retarder. Then the compressive and flexural properties of the 3D-printed aluminate cement-based composites were evaluated, as well as the residual mechanical properties after heat-treatment at 200, 400, 600, 800, and 1000 °C, respectively. The pore distribution characteristics and the difference between the interface and matrix areas of 3D-printed composites after heat-treatment were systematically quantified through CT microscopic examinations and their relationship with the mechanical anisotropy was clarified. Additionally, the microstructural evolution were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and thermogravimetric-differential scanning calorimetry (TG-DSC) technologies. The results indicate that high temperature has a more significant effect on the interfaces of 3D-printed concrete, and the increase of porosity at interfaces was 23 % higher than that at the matrix after exposure to 1000 °C. At different temperatures, the average porosity in the Y direction was lower than that in the X and Z directions, and therefore result in the damage anisotropy.