How can I replace the crumbled weight base of my torchiere lamp?

I fixed mine by attaching a 5 lb barbell weight to the bottom in place of the original base

I got a table lamp kind thing, but this is close to 7 feet and same as you I broke the bottom plaster too . I am thinking of getting a round plate (exercise weights) 15 or 20 pounder that whose circumference is not bigger than the lamp base and fix it with not and bolt same as how the plaster was.. if the hole in the middle of the plate is big then put a big washer and fix the nut.. hope it helps you

Cheers,

Arjun

So is consensus, plaster will not be heavy enough on its own? I am going to put 4" PVC over inner opening, in underside of metal base. To make room for working the nut back on to the lap pole rod. Then fill it up with plaster or whatever. The metal base is 5 " deep. Still thinking through, what to use to make it heavier. On a continued note-the concrete inner base covered in hard plastic coating, just disintegrated, plastic also. Can break with your hands. Must be the lye in concrete. Also need to make sure metal base strong enough to hold weight of lamp straight. The original plastic covered concrete had a plastic bracket to bolt the rod to.

I used a bar bell weight with plastic feet bolted in, I drilled 4 holes from the top down and used big washers to bolt it in with nylock nuts then repainted the base flat black, the bolts are not really noticeable

backerboard - It weighs the same as concrete because it is concrete (without the rocks). Backerboard has a re-bar like (fiberglass) mesh reinforcement so it doesn't crumble. It is easy to carve as 40 year old set concrete (not). I use a concrete drill to rough out the shape, then a hammer, chisel, jigsaw, and a collection of blades to break through the fiberglass. It takes a lot of patience and a good collection of swear words.