Composites of technical textiles used as reinforcement and fine-grained concrete used as matrix, called textile reinforced concrete (TRC), provide the opportunity to construct thin structural elements. Typically, the reinforcing textiles are made of yarns consisting of hundreds of alkali-resistant glass filaments, which leads to a complex microstructural behavior, especially with respect to bond. In order to reveal its complexity some experimental investigations are summarized. It is recognizable that the bond between concrete and filaments is subject to some deficiencies. Therefore, mechanical models are required to describe the early failure of single filaments as well as the bond and friction behavior of filaments and concrete. The mechanical models are solved numerically within a finite element framework. Exemplary calculations for an ideal yarn and important cases of deficiencies show typical properties of the load carrying and the bond behavior.