Experimental Study On Carbon Fiber Reinforced Concrete Under Water

With the development of the science of concrete materials, the concrete materials are more and more widely applied in large-scale structure project. Meanwhile, the concrete materials, by themselves, have their inherent defects such as low cracking resistance, which bring increasing hazards and seriously affect the security and persistence of large-scale concrete constructions. As a result, it has become an important scientific question concerning the national sustainable development to research on the safety and healthy monitoring of constructional facilities of important projects. As the carbon fiber reinforced concrete (CFRC) has an extensive future on the realization of non-destructing test, on-line monitoring and repair of civil engineering, they are attracting more attention day by day.To add carbon fiber to concrete, on the one side, can improve the intensity and impermeability of the concrete making it more suitable for underwater concrete construction; on the other side, the carbon fiber can greatly improve the conduction of electricity and carry on non-destructing constructional tests according to the changing rules of electricity resistance. This thesis works on the experimental analysis of the impermeability as well as the conduction of electricity of CFRC, and also that of cracking diagnosis in under-water environment. By making a contrastive analysis between CFRC and ordinary concrete, it studies the superiority on the compressive strength and impermeability, the influence of such elements as the proportion of carbon fiber, the length of fiber on the impermeability of concrete. As for the electric conductivity, the thesis makes an research on the influence of the instars of concrete, the proportion of carbon fiber, water ratio as well as external water pressure on the electric conductivity of concrete by means of experiments. Through taking insulant as cracks of concrete, it analyzes the dimension of cracks by the variation of the electric conductivity and so on, which provide a theoretical foundation for the application of intelligent carbon fiber to engineered constructional monitoring in under-water environment.The results of the experiment indicate that carbon fiber is of significant advantages on the aspects of intensity and impermeability. By adding a appropriate amount of carbon fiber, the concrete can be more intensive and impervious, which depends basically on the proportion and length of carbon fiber. The electric conductivity increases with the increasing of the proportion of carbon fiber until percolation threshold, and after that, there is no significant increase. The higher the proportion of water in concrete, the better its electric conductivity is. The major element that affects the electric conductivity of defected carbon fiber is the area of insulation sheet, by contrast, its position and number have little influence.