In the previous post we have learned about the difficulties in reinforced cement concrete jacketing. In this post we will learn about how they are overcome. As we discussed before, the problems are making act both old concrete and new RCC jacketing as composite member. The calculation for strain compatibility should be considered carefully tacking account for creep.
The problem that are mentioned before are old concrete has reached limiting strain and reinforcement has corroded with a porous concrete. Now we will find the solution for these problems.
The question is: should old concrete be ignored i.e. composite action is abandoned and provided new reinforced cement concrete jacket will be designed to take entire load that may arise to a particular member like column. This is perhaps the best solution to design for strengthening in this method. But this is ensured only by the proper detailing that ensures applied load to transfer to new RCC jacketing as old one fails. But for economy, during design process the actual capacity of existing old concrete should be determined carefully.
However, it is necessary to provide a perfect bond between new concrete and old concrete by applying epoxy to provide a bond coating and providing suitable space for shear keys. A typical example of providing shear key with the application of resin mix will be discussed in the next post.