Use of supplementary cementing materials for cost-effective repair of marine corrosion damage

Corrosion damage is caused by penetration and diffusion of chloride ions into the outer layer of the concrete, causing the destruction of the gamma-ferric oxide layer on the reinforcement. The selection of materials for repairs of corrosion damage in reinforced/prestressed concrete is more difficult than for new construction. The range of materials used is broader than just cementitious materials, because many polymeric composites can be used effectively for concrete repair. Frequently, the period in which the structure can be brought back into service, the accessibility, and the position of the repair in relation to the level of the tide are also important considerations in the selection of materials and methods for repair. In the earlier analytical investigation by Reddy et al. [2004] the time for chloride concentration to reach the threshold value that initiates corrosion in the reinforcement was determined by Fick's law, extended to 2-D and 3-D chloride diffusion, for a) uncracked concrete, and b) for cracked concrete with the Simplified Smeared Approach (SSA). The structural integrity of the concrete circular pile was compared, before and after repair, by a) finite element modeling using ANSYS software with the maximum deflection, and b) beam strength analysis to find the moment capacity for cracked and ultimate conditions. The overall analytical findings indicated the adequacy of the repair procedures. The objective of the on-going experimental investigation is the comparison with the analytical values. Six different types of repair are being carried out on sets of three specimens. All the specimens will then be exposed to simulated tidal conditions in seawater tanks to determine their durability. Ultimate strength testing will be carried out to determine the loss of structural integrity.