Abstract
Deteriorated concrete structures due to corrosion cracks and with fallen concrete cover are often repaired by removing the cracked concrete around the corroded reinforcement and replacing it with new concrete or with special repair mortar. This process is often referred to as “Mechanical Repair” and is widely used for repairing deteriorated reinforced concrete members. Mechanical repair leads to the formation of an ‘interface’ between the ‘parent concrete’ and repaired material. The structural behaviour of the repaired members is critically depended on the performance of the interface. This paper reports the results of static and fatigue tests performed on a total of 21 beams, cast in two stages to resemble the mechanical repair. Location and dimensions of the repair and the repair material are taken as variables in the study. Results of the static tests on repaired beams reveal that static performance can be restored by the mechanical repair. Compressive face repair can even improve the performance depending on the properties of repair material and the performance of the bond. However, the fatigue performance of the repaired members is found very different to their static performance. All most all repaired beams either the repair of the compression face or of the tension face failed at substantially lower number of cycles compared to the control beam. Among the repaired beam, tension face repaired beams showed the most significant reduction in the fatigue performance.
Highlights
Accumulation of corrosion product exerts pressure on the surrounding concrete which leads to de-bonding of reinforcement bars and cracking and spalling of concrete
Recommendations for material selection, repair techniques and other valuable information relating to mechanical repair can be found from the Repair manual published by the International Concrete Repair Institute [10] and stands out as state of the art guideline on repair of concrete structure
When compared with the 80% against the 40% repair length in the tensile face, it is clear that lesser the length of tensile face repair more effectively it restores the static performance in terms of initial stiffness and ultimate load carrying capacity
Summary
Some time even the new ones, built in corrosive environments (Sheffield), Senior Lecturer in Civil and Environmental Engineering, Faculty of Engineering, University of Ruhuna, Hapugala, Galle It is not always practical nor economically viable to demolish and replace a building with corrosion damage, especially, when the building is found to be structurally sound and very expensive to replace like in the case of this hospital building with a floor area in excess of 3,000 m2 (30,000 Square feet) [2]. With many deteriorated structures along the costal belt being considered for mechanical repair, the need to understand the correct techniques and its possible limitation and structural implications is considered invaluable It is in this backdrop that the result of the behaviour of repaired beams is presented here. The paper provides insight to the best known practices of mechanical repair, the performance, limitations and the structural implication of the technique
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