Mechanical and structural characterization of mini-bar reinforced concrete beams.

摘要

With major breakthroughs in material science in recent years, civil engineering construction technology has simultaneously gone through major paradigm shifts. From the conventional reinforcing material like steel, we witnessed the introduction of fiber reinforced polymer bars (FRP), fiber reinforced polymer wraps and multitudes of chopped reinforcing fiber materials, metallic and synthetic in recent times.;This dissertation covers a comprehensive research program that was undertaken at the University of Akron for the mechanical and structural characterization of concrete reinforced with new type of reinforcing fiber material, called as Basalt minibar. Basalt minibar is a non-corrosive structural macro fiber made from basalt fiber reinforced polymer (BFRP) bars. It is manufactured using a simplified automated method called wet-ley up process. Basalt mini-bar possesses higher tensile strength and stiffness compared to other standard synthetic fibers and at the meantime it is non-corrosive. Fibers act as the proactive reinforcement that provides the immediate tensile load carrying capacity as soon as micro cracks develop in concrete. Fiber reinforcement can be used as the proactive load carrying element and can also be used as supportive reinforcement to control issues like shrinkage in concrete. This demands for a type of a material which is durable, has adequate strength and stiffness to impart sufficient toughness to the structure and can mix well with concrete, developing good bond strength.;The primary motivation behind the research is to characterize Basalt mini-bar as a new hybrid-material which possesses the beneficial features of both metallic and synthetic fiber. The overall goal of the project was achieved through tensile strength characterization of Basalt fiber reinforced polymer (BFRP) bars, followed by mechanical and toughness characterization of minibar and minibar reinforced concrete (MRC), leading to strength characterization of minibar reinforced concrete (MRC) beams, finally completed with some preliminary studies on thermal behavior of minibar reinforced concrete (MRC) slab.;Based on the experimental test results and the subsequent analyses findings, it was observed that Basalt fiber reinforced polymer (BFRP) bars exhibit strength size effect. The flexural tensile strength and post-cracking tensile strength of MRC were found to increase significantly with minibar dosage within the range considered (2 to 10%). It was observed that post-cracking behavior of beams (ductility, deflection) was significantly improved due to the addition of basalt minibar. The beams were capable of undergoing larger deformation, thus exhibiting increased maximum tensile strain at failure. Theoretical models were developed to account for the number of minibar across the crack plane, maximum load carrying capacity of MRC beams and the increase in shear strength due to the addition of minibar. The structural response of MRC slab under high temperature was found not to be satisfactory.;It is believed that the dissertation provides insight into essential mechanical properties of minibar and minibar reinforced concrete. This can be further used in coming times by the new generation of engineers to study long term behavior of these materials for various durability characterizations.