Abstract
This study presents the key mechanical and residual properties after high-temperature of different Nano SiO2 carbon fiber-reinforced concrete (NSCFRC) mixtures. A total of seven NSCFRC mixtures incorporating 0%–0.35% of carbon fiber by volume of concrete and 0%–2% Nano SiO2 by weight of the binder were studied. The key mechanical properties such as compressive strength, tensile strength, and flexural strength of NSCFRC with 0.25% carbon fiber and 1% NS were 6.8%, 20.3%, and 11.7% higher than PC (0% CFs, 0% NS), respectively. Scanning Electron Microscopy (SEM) shows that Nano SiO2 reduced the internal porosity and increased the compactness of the concrete matrix. Furthermore, the experimental result demonstrates that NSCFRC can improve the mechanical properties of concrete after high-temperature and equations were obtained to describe the evolution of residual properties at elevated temperatures. Results suggested that the effect of carbon fibers on the residual properties of concrete after high-temperature is less than steel fiber and polypropylene fiber. It was also indicated that adding appropriate Nano SiO2 to concrete is an effective means to improve the residual performance after high-temperature.
Highlights
Concrete is one of the most widely used building materials, but its tensile strength is relatively low compared to compressive strength
This study presents the experimental results obtained on seven Nano SiO2 carbon fiber-reinforced concrete (NSCFRC) mixtures subjected to high temperatures
The residual compressive strength of NSCFRCs is higher than polypropylene fibers reinforced concrete (PPFRC) by Aslani et al and Ding et al because the residual compressive strength reduces when the temperature is above 375 ◦ C due to the fiber has been melted up at such high temperature and the pores left are disadvantageous for the performance of concrete [32,33]
Summary
Concrete is one of the most widely used building materials, but its tensile strength is relatively low compared to compressive strength. Carbon fiber-reinforced concrete (CFRC) has been used in many projects since the 1970s due to its good thermal conductivity, lightweight quality (low density), and high modulus of elasticity [4,5,6,7,8,9] It can effectively improve the tensile strength, flexural strength, impact resistance and crack resistance. In order to improve the mechanical properties of CFRC after high-temperature, Nano SiO2 (NS). Heidari [18] shown that the incorporation of nano-SiO2 particles can significantly improve the compressive, flexural, tensile strength and toughness of concreteIn addition, NS can improve the mechanical properties of concrete after high-temperature. The evolution of residual mechanical properties with temperature were investigated in order to explain the influence of carbon fiber and NS on the mechanical properties of concrete after high temperature
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