| There is a critical need for new construction materials and construction techniques for repair and rehabilitation of infrastructures. High strength fiber composites, known as Fiber Reinforced Polymers (FRP) are being used for rehabilitation of structures during the past 20 years. Wet-hand-lay-up is the standard procedure used for attaching high strength carbon or glass fibers or fiber sheets to concrete, reinforced concrete and steel structures. Based on the experience of aerospace industry, vacuum bagging technique that is suitable for repair of structures in the open construction environment was developed. Extensive laboratory investigation was conducted to identify suitable reinforcement, polymer, materials for vacuum bagging including; sealant tape suitable for concrete placement, vacuum bagging and curing sequence. This investigation culminated in the field demonstration project for fabricating a pier cap jacket in an actual bridge in Rhode Island.; FRP has a number of advantages over the conventional structure materials but they are the susceptible to fire, UV radiation and the compatibility of FRP with concrete in terms of permeability and coefficient of thermal expansion. These shortcomings can be remedied using a recently developed inorganic polymer. The results presented in this dissertation deals with the behavior of beams made using bricks and high strength fiber fabrics. These specimen geometries were chosen to simulate the behavior of brick walls strengthened with high strength fibers. Feasibility of using the inorganic polymer for strengthening clay, concrete and hollow core brick walls, failure mechanism, strength increase, ductility and toughness were evaluated. An analytical model for predicting the capacity of strengthened beams is also presented. The inorganic matrix, reinforced with short fibers was also evaluated for use as a coating material for concrete structures. The coating provides a protective layer which provides vapor pressure release. In addition, the coating has a high hardness and amorphous glassy finish with excellent resistance to graffiti.; A new failure criterion for estimating the moment capacity of strengthened reinforced concrete members is proposed. Experimental investigations conducted all over the world demonstrated that the maximum carbon fiber strain at failure is always around 0.008 even though the fracture strain of carbon is 0.015. The criterion proposed in this dissertation addresses this anomaly. The new criterion provides reasonably accurate predictions. |
