On May 16, 7:33*pm, Joe wrote:
On May 16, 5:12*pm, Bob wrote:

snip

The fact that the original bolts failed makes the chances of getting a
good anchor with expansive bolts risky. If the concrete was new and
well cured it would be different. A much used safer technique these
days is to drill and clean the holes out and install stainless steel
studs bedded in epoxy. There are several companies supplying material
for this and the end result is far more permanent than Tapcons or
Redheads from a corrosion standpoint. *The cost is a bit more than the
expanders, and there is a wait for cure time. Also, low temperatures
mean waiting for better weather.
This technique is frequently used for repairing rusted out toilet
mounts on slab foundations.

Joe

I third Joe's advice. Use epoxy, not mechanical expansion.