Q.: I am a structural engineer and am investigating a problem with a parking garage below grade. This garage is part of a larger building and projects beyond it. It has a two-way flat slab at grade like a bridge. It is about 6 years old. There are cracks over the large rebars, some of which are #10 bars. The drawings show only 1/2 inch of cover over the steel, and some rusting is visible. There is cracking in the slab, mostly over the columns. The owner is not prepared to do major structural repairs immediately. What I would like to know is whether we could inject the cracks with an epoxy and get 4 or 5 more years out of the garage before undertaking major structural work? We would monitor the performance in the meantime.
A.: The fact that you plan to monitor the performance makes the plan sound safe. That makes the answer boil down to one of economics. An epoxy properly applied should remedy the existing problem though it would not prevent the continuing deterioration associated with too little cover and too much deicer salt probably already in the slab.