Experimental study on dynamic mechanical properties of 3D printed cement-based materials under splitting tension after high temperature

Abstract

3D printed cement-based structures are subject to fire risk during service, and the study of static and dynamic mechanical properties of 3D printed cement-based materials after high temperature is of great significance for calculating and evaluating the safety performance of their applied structures after fire. Therefore, this paper focuses on the study of the dynamic mechanical properties of splitting tensile of 3D printed cement-based materials after high temperature, setting five temperatures and four strain rates, applying hydraulic servo machine to carry out the experimental study on the static and dynamic mechanical properties of splitting tensile of 3D printed cement-based materials, thus analyzing the influence of high temperature and strain rate on the mechanical properties of splitting and stretching of 3D printed cement-based materials, and mainly obtaining the following conclusions: with the temperature increasing, the 3D printed cement-based materials are more prone to cracking than ordinary concrete, and the structure of 3D printed cement-based materials is more loose. The change of damage pattern of the specimen is influenced by a strain rate lower than that of ordinary concrete. As the temperature increases, the tensile strength of 3D printed cement-based materials decreases gradually, and the tensile strength of specimens under different strain rates is reduced by 85∼90% under the influence of temperature increase. As the strain rate increases, the tensile strength of 3D printed cement-based materials gradually increases, and the increase in temperature leads to a gradual decrease in the tensile strength of specimens affected by the increase in strain rate. Based on the J-criterion, a calculation model of the change in tensile strength of 3D printed cement-based materials by strain rate after considering the effect of temperature is proposed. At the same time, a scanning electron microscope is applied to obtain the microscopic morphology of 3D printed cement-based materials after different high temperature and reveal the mechanical mechanism of the coupling of high temperature and strain rate effects. The results of the study provide a theoretical basis for the calculation and analysis of the dynamics of post-high-temperature 3D printed cement-based structures.