# Study on Frost Resistance of the Carbon-Fiber-Reinforced Concrete
## 1 Introduction  
About half of concrete buildings have different degrees of freeze-thaw damage worldwide [1]. Globally, in cold regions, such as Northern Europe, Russia, Canada, Japan, and the northern part of the United States, concrete structures have different degrees of freeze-thaw damage, and the cost for maintenance and reinforcement is quite significant [1]. The economic loss caused by the freeze-thaw damage of buildings is much higher than the construction cost [1]. Concrete structures are often subjected to freeze-thaw cycles, and their mechanical properties and durability will be reduced by various degrees or even damaged, especially in a salt-rich environment [2]. Thus, it is highly necessary to study how to improve the frost resistance of concrete.  
However, very limited data is available in the literature on the frost resistance performance of fiber reinforced concrete [2]. Adding polypropylene fibers into concrete could slightly increase the frost resistance of concrete, as argued by [PERSON] et al. [3]. According to [PERSON] et al.'s [4] study, the addition steel fibers can improve frost resistance. To improve the performance of concrete, various fiber-reinforced concretes (FRCs) that are made of cement, water, aggregate, and dispersed fibers e.g., synthetic fibers, steel fibers, glass fibers, polypropylene fibers, and carbon fibers, are extensively used [5; 6; 7]. At present, steel fibers, carbon fibers, and polypropylene fibers are the most common materials for FRC [6]. Steel FRC has a high compressive strength, crack resistance, and toughness [7; 8]. However, steel fibers can easily rust in humid and corrosive environments. The addition of steel fibers decreases the flowability of FRC to some extent, which would reduce the workabilityof the FRC significantly. The addition of polypropylene fibers can greatly improve the non-deformability of the concrete, increase the toughness, and improve the fatigue and impact resistance [2]. The strength of polypropylene FRC is also improved by a small degree. However, owing to the low elastic modulus, unmodified polypropylene fibers do not bond to concrete very well. Carbon fibers have many advantages, such as a high elastic modulus and strength, low density, and fatigue and corrosion resistance. The carbon fibers added to the concrete improve the strength [9; 10], crack resistance [11], and flexural resistance [12] of the concrete. The CFRC was also resistant to high temperatures [13]. However, the aforementioned studies mainly concentrated on the mechanical properties of CFRC at room or high temperature, while little experimental research and analysis has been conducted on the frost resistance of CFRC at low temperature conditions.  
The volume fraction of the fibers influences the mechanical properties of the concrete, e.g., strength, toughness, impact resistance and so on [7; 8; 9; 10; 11; 12]. This study primarily examines the effects of the carbon fiber content on the frost resistance of CFRC at low temperatures, and estimates the correlation of the amount of fiber and frost resistance. It would provide a scientific reference for improving the frost resistance of concrete under cold conditions.