ABSTRACT

Deterioration of existing structures due to change in material properties, inferior design, environmental action, or increase in traffic loads in the case of bridges, often requires new rehabilitation techniques. Retrofitting/strengthening with composites/tendons is shown it to be superior over the classical rehabilitation methods using steel plates. This paper presents and demonstrates how polymer matrix composites developed for high-performance aircraft can offer significant advantages -for repair and retrofitting of aging infrastructure. Design criteria for the use of composite materials are suggested and the paper presents the use, research and development and several practical applications of composites in upgrading of concrete structures.

INTRODUCTION

The significant challenge facing the concrete construction industry is the deterioration of the infrastructure. The immediate need for the nation's infrastructure is the rehabilitation or repair of bridges, buildings, and highways. Many of the nation's bridges and other civil engineering structures are deteriorating due to problems associated with corrosion of steel in reinforced concrete. Forty percent of the nation's 575,000 bridges are structurally deficient or functionally obsolete, and 25 percent are years old or more and are unsuitable for current or projected traffic needs. The effects of environment (harsh climate, de-icing salts, seismic activity, etc.), the increase in both traffic volume and truck weights and inadequate design of older structures are factors which contribute to, the infrastructure deterioration. The replacement or repair/upgrade cost using traditional materials and methods becomes increasingly expensive and hence composites are being explored as a promising, material to these problems worldwide. Advanced polymer matrix composite materials developed for high performance aircraft offer major advantages for rehabilitation and retrofitting of existing civil engineering structures through external bonding of FRPs. The use of composites has received considerable attention due to their high strength, high stiffness, resistance to corrosion, low weight, nonmagnetic and nonconductive properties.

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