After years of service, many concrete buildings are facing the problem of deterioration. In aging buildings, steel corrosion is one of the major problems causing spalling of concrete cover and loss of strength in the structural members. Traditionally, if the loss in steel area is small, the spalling will be simply repaired by patching. If the loss in steel area is high, the structural members will be simply repaired by attaching external steel plate with anchors or lapping a new reinforcement to recover the load carrying capacity. However, these methods are labour-intensive, costly and time-consuming. In this thesis, an effective and innovative repair method is developed. A repair mortar of sufficient tensile strength will be developed by adding steel fiber into the mortar. Diff...[ Read more ]

After years of service, many concrete buildings are facing the problem of deterioration. In aging buildings, steel corrosion is one of the major problems causing spalling of concrete cover and loss of strength in the structural members. Traditionally, if the loss in steel area is small, the spalling will be simply repaired by patching. If the loss in steel area is high, the structural members will be simply repaired by attaching external steel plate with anchors or lapping a new reinforcement to recover the load carrying capacity. However, these methods are labour-intensive, costly and time-consuming. In this thesis, an effective and innovative repair method is developed. A repair mortar of sufficient tensile strength will be developed by adding steel fiber into the mortar. Different types of mortar and steel fiber are investigated in terms of mix composition and fiber geometry. Tests are first performed to measure the direct tensile behavior of the fiber reinforced mortar. After identifying mixes with sufficient tensile capacity to compensate for the loss in steel area encountered under practical conditions, bond tests are carried out to study the required bond length of repair mortar patch along the steel reinforcement. The results of this study demonstrate the promise of a new cost-effective approach for the repair of reinforced concrete buildings.