Fixing a window into a precast concrete section

[Davehawthorns]

When I moved into my present house about 17 years ago I inherited a garage made from precast concrete sections. This weekend a window fell out and I'm struggling to work out how to put it back. It's obviously toughened glass because it didn't break.
There are no window frames in the sections - the glass simply fits into recesses in the walls measuring 680 mm tall x 190 mm across.
The old glass (which is going back in- I hope) and the others in the garage have a fillet of something around the inside face which feels suspiciously like putty to hold them in. There is no trace of any adhesive on the recess left vacant by the glass falling out, but I'm far from certain that something as simple as putty is the answer, particularly since it lasted so long last time.
Can anyone please offer some advice on what might be the answer?
Many thanks for any advice on sealants/bonding agents/glue and even the merits of putty!

Dave

 

[maltaron]

Putty is the normal way to glaze in these circumstances. The only problem is that in concrete there is no way of inserting pins as is done in wooden frames. That is probably the reason that it has eventually fallen out as the putty lost its grip on the concrete. I would suggest that you drill two holes in the frame about 30mm deep and knock in a bit of wood to take pins. Bed the glass in putty and insert pins to hold it, then face putty and finish.