Repair of heat-damaged reinforced concrete T-beams using FRC jackets

A series of 16 under-reinforced concrete (RC) T-beams were cast, heated at 600°C for 2·5 h, repaired and then tested under four-point loading to study the effectiveness of using externally applied high-strength fibre reinforced concrete (FRC) jackets as a method of increasing the flexural capacity of beams. The overall response of the beams loaded up to failure, the onset of cracking and cracking pattern, serviceability, stiffness and ductility were described. Four types of fibre were used: glass, high-performance polypropylene (HPP), hooked end steel and brass-coated steel (BCS) with fibre content ranging from 1 to 2%. The beams repaired with steel-FRC jackets applied at the sides of the beams' web and the bottom of the flange, exhibited a substantial improvement in their flexural behaviour compared with control (undamaged) ones. They regained a large proportion of the control beams' ultimate load capacity, and showed a typical flexural failure with an increase in the first cracking load. The beams repaired with HPP and glass fibres exhibited a marginal improvement in their flexural behaviour compared with control ones with a typical flexural failure and a decrease in the first cracking load. Based on the findings of the present study, high-strength steel-FRC jackets may be considered as a promising material for maintenance and rehabilitation of concrete structures.