Repair of Reinforced Concrete Beams Damaged by Alkali-Silica Reaction
J.,, Shannag, M. . 2008
A series of twelve under-reinforced high strength concrete rectangular beams were cast, subjected to exposure conditions chosen to generate a rapid increase of alkali-silica reaction (ASR) damage, repaired and then tested under four-point loading to determine the effectiveness of using externally applied U-shaped high-strength fiber reinforced cementitious jackets as a method of increasing the beams’ flexural capacity. The overall response of the beams (loaded up to failure), the onset of cracking, and cracking pattern, serviceability, stiffness and ductility were described. Three types of fibers were used, high performance polypropylene, hooked end steel and brass coated steel with fiber content ranging from 1 to 2%. All repaired beams exhibited a substantial improvement in their flexural behavior compared to 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 and service loads. Beams, repaired with a mixture of hooked steel and brass-coated steel fibers, showed the highest improvement in flexural load capacity reaching as high as 119%, whereas those repaired with brass-coated steel fibers exhibited the highest improvement in displacement ductility and toughness; reaching as high as 145 and 176% of those of control beams. An analytical model was developed for predicting the ultimate load capacity of the repaired beams. The predictions of the model compared well with the experimental test results.
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