Influence of Selected Impregnation Materials on the Tensile Strength for Carbon Textile Reinforced Concrete at Elevated Temperatures

Carbon textile reinforced concrete (CTRC) has been investigated in terms of its elevated temperature and fire behavior in order to evaluate the influence of impregnation materials. Elevated temperature tests have already been carried out for material combinations of CTRC. For the tensile strength and the bond behavior between textile reinforcement and concrete, the impregnation of the textile reinforcement is the influencing factor. Impregnation materials such as epoxy-resin (EP) or styrene butadiene rubber (SBR) showed a deterioration of the elevated temperature behavior compared to unimpregnated materials. The aim of this paper is to close the research gap on the elevated temperature behavior of carbon textile reinforced specimens impregnated with silicic acid ester, epoxy-resin, and epoxy-resin additionally surface-modified with quartz sand. For this purpose, stationary and transient tensile tests at elevated temperatures up to 1000 °C were performed. Furthermore, thermal analysis of the impregnation materials was performed to analyze the tensile tests by correlating the chemical examination with the experimental test results, and the ignitability of the reinforcements was studied using single flame tests. For the investigated reinforcement materials, the failure temperature of the specimens increases with decreasing tensile strength load level for all test specimens. In comparison to the epoxy-resin impregnation material, the silicic acid ester impregnation resulted in higher failure temperatures for comparable load levels. The decomposition of the impregnation materials proved to be a decisive factor due to comparatively evaluated thermal analysis.