As in the United States, Japan faces a critical need to retrofit and rehabilitate its civil infrastructure ranging from buildings and parking structures to bridges, tunnels and irrigation channels. The replacement of most of the deteriorated or functionally deficient civil infrastructure is not a feasible option in most cases for several reasons ranging from economics and logistics to the socio-economic impact of detours/delays/inconvenience to inhabitants and industrial output over considerably long periods of time. A large percentage of concrete structures that were built in the 1950s, although still in good condition, do not meet the need of current traffic loads, seismic standards or building usage. Others built in the boom of the 1970s used subgrade materials such as alkali-active aggregate and sea-sand, resulting in severe deterioration from cracking of concrete, exfoliation and severe corrosion of reinforcing steel. Some structures built in the early 1980s had deficiencies in design or materials due to constraints on resources placed by a tight economy. These structures need to be strengthened/repaired and brought up to code to ensure that they meet serviceability and strength/stiffness criteria. Although some of these structures can be rehabilitated using conventional techniques, others cannot due to reasons ranging from structural and functional to those related to logistics and socio-economic impact. The use of fiber-reinforced composites presents an attractive option in such cases due to their enhanced mechanical performance, environmental durability, corrosion resistance, light weight and rapid application potential.

Published: November 1998; WTEC Hyper-Librarian