Degradation of mechanical properties of 3D fiber reinforced printed concrete mixtures exposed to elevated temperatures

Utilization of 3D printed concrete (3DPC) materials significantly increased in the construction and building industry. In this study, different series of 3DPC mixtures containing three types of fiber (steel, basalt, and polyamide) and concentrations (0.2, 0.4, and 0.6%) are produced and tested under different elevated temperatures of 300, 600, and 900 °C. The evaluated properties include the weight loss, compressive strength, and flexural strength determined in three different loading directions (parallel, perpendicular, and lateral), water absorption, and microstructure changes. Test results showed that the durability of 3DPC mixtures gradually curtailed at increased exposure temperatures. The loss in compressive and flexural strength hovered between 34-56% and 28-73%, respectively, when the mixtures were exposed to 900 °C. The best heat resistance performance was achieved using the 3DPC mixture containing 0.4% steel fibers, while the weakest mix contained 0.6% basalt fibers. Such data can be of particular interest to concrete engineers and designers seeking the use of fiber reinforced 3DPC materials in applications exposed to elevated temperatures. • The main objective of the research was to assess durability, mechanical properties, and microstructural changes of fiber reinforced 3DPC mixtures subjected to elevated temperatures. • Three types of fibers including steel, basalt, and polyamide were used at 0.2%, 0.4% and 0.6% rates, by volume. • The experimental program included water absorption, weight loss, and mechanical properties at ambient and high temperatures. • Results showed that durability of 3DPC mixtures gradually curtailed at increased exposure temperatures. • The loss in compressive and flexural strength hovered between 34-56% and 28-73%, respectively, when the mixtures were exposed to 900 °C. • The best performance was achieved using the 3DPC mixture containing 0.4% steel fibers, while the weakest mix contained 0.6% basalt fibers.