Comparative study on the static and dynamic mechanical properties and micro-mechanism of carbon fiber and carbon nanofiber reinforced concrete

In order to compare the effects of carbon fiber and carbon nanofiber on the static and dynamic mechanical properties of concrete, the static mechanical tests, dynamic compression test and dynamic splitting tensile test were carried out on carbon fiber reinforced concrete (CFRC) and carbon nanofiber reinforced concrete (CNFRC). Meanwhile, relevant micro-mechanism was analyzed through the MIP test and SEM test. The results showed that both carbon fiber and carbon nanofiber could improve the mechanical properties of concrete and refine the pore size distribution of concrete. In terms of the static mechanical properties, the ductility of CFRC was better, while the strength performance and deformation performance of CNFRC were better. In terms of the dynamic compression mechanical properties, the energy consumption performance of CFRC was better, while the strength performance of CNFRC was better. In terms of the dynamic splitting tensile properties, the strength performance, deformation performance and energy consumption performance of CFRC were better. Under a load, carbon fiber exerted a more obvious “crack resistance effect”, while carbon nanofiber exerted a more obvious “filling effect”. Carbon nanofiber had a better optimization effect on the pore structure of concrete than carbon fiber. The research results could provide reference for the selection of CFRC and CNFRC under different engineering requirements.