Performance of Phosphazene-Containing Polymer-Strengthened Concrete after Exposure to High Temperatures

Abstract

The strength properties of concrete strengthened with a polymer including phosphazene after exposure to high temperatures is investigated in this study. The Taguchi L25 (55) method was used to reduce the number of experiments and to find the parameters affecting the experimental results. Percentage of phosphazene in the monomer (%, 1%, 2%, 3%, and 4%), curing period (28, 6, 9, 18, and 365 days), cement content (3, 35, 4, 45, and 5 kg/m3), and high temperature (2°C, 2°C, 4°C, 6°C, and 8°C) were chosen as experimental parameters. For the experiments, 1×1×1 mm cubes were prepared. The specimens were removed from water after the end of predetermined curing times and dried at 15±5°C. Then, they were exposed to temperatures of 2°C, 4°C, 6°C, and 8°C. The next step was impregnation of the samples with a vinyl acetate monomer containing phosphazene for a 24-h period under atmospheric conditions. The polymerization of specimens was conducted at 6°C for 4 h. The compressive strength, ultrasonic pulse velocity, and changes in weight were determined for the specimens. Furthermore, X-ray powder diffraction (XRD), energy dispersive X-ray (EDX), and scanning electron microscope (SEM) image analyses of specimens were carried out. The findings showed that the best results were found from specimens with low cement content and 3% polymer containing phosphazene. Therefore, this study has found that polymer containing phosphazene can strengthen buildings exposed to high temperatures.