In the previous post we have discussed about concrete member repair options. Among the options described there, we will discuss about reinforced cement concrete jacketing in this post. Reinforced concrete as jacketing existing weak or to be strengthened concrete member is used to increase member size. Increasing member size produces a member of greater stiffness to perform well against deformation of existing less stiff reinforced concrete member.
Columns in a RCC structure are the common member that is strengthened by this method. This method produces a stiff column that was slender before strengthening. Now we will learn about the problems that can be arisen in RCC jacketing.
a. The existing old concrete cannot sustain a significant amount of strain. It has already reached its limiting strain.
b. The existing concrete is very weak with significant amount of porosity that gets deteriorated by the action of weathering and reinforcement get corroded.
The both problems are related with the acting of both old and new concrete as a composite section of a composite member. Only when stress and subsequent strain in parent member is increased doe to applied load, the new concrete as jacket can take additional loads to become a composite member to act as unit.