The rehabilitation of structurally deficient and substandard civil infrastructure has become a major concern for the civil engineers worldwide. According to an analysis report issued by The American Road and Transportation Builders Association (ARTBA), well over 50,000 bridges in the US are structurally deficient. These are alarming figures which need to be given due attention. Concrete structures built before 1990 had little attention paid to disaster and corrosion resistance. Insufficient progress in seismic engineering was the main reason why earthquakes caused irreparable damage to infrastructure in the 20th Century.
Before proceeding further, it’s important to differentiate a few commonly used terms. When it comes to the concept of rehabilitation of concrete structures, we use terms repair, strengthening, and retrofitting interchangeably and often erroneously. The term repair refers to the use of certain material to remove the structural deficiencies while strengthening means to enhance the performance of an existing design. The term retrofitting is used specifically to refer the seismic upgradation of a structure.
Degradation of concrete structures
Concrete structures deteriorate with the passage of time and there is a number of factors that contribute to this process. Service conditions and the quality of construction material are two major factors that determine the life of a concrete structure. However, the deterioration process can be rectified or slowed by carrying out due maintenance. Without rehabilitation, a steel-reinforced structure is unlikely to achieve the desired service life. Following are some of the common causes of structural degradation:
- Corrosion is one of the biggest threat to civil engineering structures. The corrosive environment can seriously diminish the strength and capacity of a building.
- The use of steel bars and other substandard reinforcement materials that cannot withstand the severity of environment.
- Engineering errors can also be one of the causes of concrete deterioration. Inferior construction workmanship and inappropriate alteration techniques result in deficient structures.
Rehabilitation of concrete structures with FRP composites
Fiber reinforced polymer (FRP) composites have been proven to be the most powerful alternative to conventional steel reinforcement. The use of FRP reinforcement for the rehabilitation of structurally deficient structures is increased worldwide mainly because of the distinctive properties of FRP reinforcement. The rehabilitation process demands lightweight, durable, corrosion-free, high strength, and easy-to-install materials and that is exactly what FRP composites offer.
GFRP fiberglass rebar, a variation of FRP composites, is preferred if an increase in ductility and strength is sought. The rate of corrosion can be reduced by using GFRP to strengthen the reinforced concrete. So far as seismic retrofitting is concerned, researchers concluded that the ductility of concrete columns can be increased by using FRP wrapping. Similarly, reinforced concrete, suffering corrosion degradation, can be strengthened by using GFRP jacketing.
Governments spend trillions of dollars annually to repair and strengthen the existing RC structures. The use of FRP composites in new and rehabilitation applications can dramatically minimize the maintenance cost in future. Composite materials will play a crucial role in building sustainable concrete infrastructure. Companies like TUF-BAR are striving to produce the best GFRP construction materials for civil engineering projects.