## 1 Introduction  
Due to aging infrastructures, the need for improvement in repair, strengthening, and maintenance processes has been continuously increasing. To improve the performance of aging infrastructures, astronomical funds have been invested [1]. Moreover, with the development of design code, structures are required to be strengthened to meet structural safety [2]. To keep up with these requirements, fiber-reinforced polymer (FRP) strengthening method has been studied and applied for many years [3; 4; 5]. Strengthening with FRP uses organic materials such as epoxy resin for bonding with concrete substrate. However, organic materials have several disadvantages, including the impossibility of applying them to wet surfaces, low glass transition temperature, low fire resistance, and low permeability. To overcome the disadvantages of the use of organic materials, textile-reinforced mortar (TRM) method using inorganic materials such as cementitious matrix has been actively researched recently [2; 6; 7; 8]. TRM is a structure-strengthening method for attaching textiles composed of fiber materials, such as carbon and glass fibers with excellent chemical resistance, to the surface of masonry and reinforced concrete (RC) structures generally using mortar. As it uses mortar, TRM is highly resistant to temperatures and applicable to wet surfaces, thus allowing efficient construction in various environments. However, since the textile consists of numerous filaments, the mortar cannot penetrate into the textile and the bonding with mortar is divided into the inner and the outer. Many researchers investigated the bonding behavior between textile and mortar and between TRM layer and concrete substrate to explain the bonding characteristics of textile composite materials [9; 10; 11; 12; 13; 14]. Furthermore, to improve the bonding between textile and mortar, textile has been impregnated with resin or attached small sand grains [15; 16; 17; 18; 19; 20]. This reinforcement of textile enables its tensile strength to be used more efficiently. [PERSON] et al. [15] coated a textile using a polymeric resin. Compared with the uncoated specimens, the load of specimen reinforced with the textile alone was increased by 26-112% in terms of the first-crack, yield and ultimate load. The load of specimen reinforced with the textile and steel rebar increased by 11-16%. The effect of strengthening using coated textile was increased when reinforcing by textile alone, or when using a smaller amount of textile. [PERSON] et al. [19] applied a partially impregnated epoxy at the interaction point of weft and warp roving in textile. Experimental results show that the maximum load of specimens with partially impregnated epoxy was increased by 49-73%. In [PERSON] et al. [21], the flexural strength of the specimens with coated textile was increased by 16% at crack and by 5% at yield and ultimate load. The failure mode of specimens was changed from premature failure due to local slippage of uncoated textile to interlaminar shearing of mortar of coated textile. [PERSON] et al. [22] also showed that the ultimate load of the specimen with coated textile was increased by 23% compared with the uncoated specimen. Commonly, impregnation or coating of textile improves the bond condition between textile and mortar. In addition, fiber alignment, prevention of relative slippage, strain compatibility of filaments, and the ease of load transferring due to strong binding of the intersection point of textile was studied [15; 19]. The process of impregnation makes it possible to use the textile more efficiently, but the efficiency differs depending on the type of the resin and textile, impregnation method, and the shape of the structure. In addition, according to [PERSON] et al. [23], the additional cost of resin and impregnation process accounts for about 38% of the fiber in terms of raw materials.