Abstract: In order to explore the size effect of splitting tensile of 3D printed cement?based materials after high temperature, the splitting tensile mechanical properties of 3D printed cement?based materials were tested by hydraulic servo machine under five temperature and three size conditions. The influence of high temperature and size effect on the splitting tensile mechanical properties of 3D printed cement?based materials is analyzed. The main conclusions of this paper are as follows: with the increase of temperature, the tensile strength of specimens decreases gradually, and the tensile strength of specimens with different sizes is basically the same under the influence of high temperature, with the maximum decrease of 87.97%. With the increase of size, the tensile strength of the specimen gradually decreases, and the increase of temperature leads to the increase of the tensile strength affected by the size effect. Affected by the size effect, the tensile strength of the specimen changes in the range of 18.488%~26.165% after different high temperatures. At the same time, based on the size effect law, a calculation model of tensile strength of 3D printed cement?based materials considering the influence factors of high temperature is proposed, and the evolution mechanism of its mechanical properties is revealed by microscopic testing technology.

Key words: 3D printed cement?based materials, high temperature, size effect, splitting and stretching