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Keywords
Steel, Reinforcement, Civil engineering
Abstract
This paper presents an overview and discusses the applications of fibre reinforced polymer (FRP) bars as reinforcement in civil engineering structures. Following a discussion of the science underpinning their use, selected case studies where FRP reinforcement has been used are presented. The use of FRP reinforcement is rapidly gaining pace and may replace the traditional steel due to its enhanced properties and cost-effectiveness. In addition, FRP reinforcement offers an effective solution to the problem of steel durability in aggressive environments and where the magnetic or electrical properties of steel are undesirable.
Introduction
Concrete structures are conventionally reinforced with steel bars and prestressed with steel tendons. For structures subjected to aggressive environments (e.g. de-icing salts in bridges, marine structures, etc.), combinations of moisture, temperature and chlorides may result in the corrosion of reinforcing and prestressing steel, leading to the deterioration of concrete and loss of serviceability. This corrosion problem of steel rebar is the greatest factor in limiting the life expectancy of reinforced concrete structures. In some cases the repair costs can be twice as high as the original cost. In North America, this phenomenon has been exacerbated in parking garages and by the use of de-icing salts and significant fluctuations of temperature. In Canada, it is estimated that the cost of repair of parking garages is in the range of 6 billion dollars, and over 74 billion dollars for all concrete structures. The estimated repair cost for existing highway bridges in the USA is over 50 billion dollars, and 1-3 trillion dollars for all concrete structures. In Europe, steel corrosion has been estimated to cost about 3 billion dollars per year. Excessive corrosion problems also exist in Arabian Gulf countries (Benmokrane et al., 1998). Deterioration in all types of reinforced structures is aggravated by excessive concentration of chlorides in construction materials, high humidity, temperatures, and marine exposure. Many environmental conditions (freeze/thaw, use of de-icing salts, moisture, chemical products, marine conditions) as well as mechanical overloads arising from ever-increasing traffic load, accelerate the corrosion process of steel rebar, thereby decreasing the life expectancy of these structures.
To increase the lifespan of reinforced concrete structures, government organisations, private industry and university researchers are seeking ways to avoid...