how to plug holes

huangyhg

how to plug holes
i am currently working on a retrofit project for which i need to drill some holes and epoxy in some rebars for a bridge barrier.
but, the problem is, due to some unavoidable reasons i have to drill the holes ahead of time and install the bars after few months. i want to plug the holes during this period, so that in the winter months the water does not get in the holes freezes and cracks the concrete.  just before installing the bars, i shall remove the plugs and proceed.  since its for bridge barrier the plugs need to be tough but easy to remove.
can you guys advise some plug materials which are easily available?
why does it need to be strong? i dont get it.
wax?  a thin layer of grout, drill out later?  silicone or urethane caulking?  
coengineer,
the only reason i want it tough because i do not want it to wear out.  i am expecting heavy construction and traffic on top of it.
it sounds like you need to solve the scheduling issue rather than finding a way to plug the holes.  if you make it durable plug then it will be hard to take it out.  it seems like it is defeating the purpose of drilling the holes early.