mount hand rails in shower

I'm working on installing hand rails in a shower. The walls are covered by cultured marble slabs with drywall behind the marble and then a 1 inch or so space for insulation, and then block behind that. My plan was to drill into the block and use lag shields to hold the bar in place. This worked on one end of the bar but it seems the block split apart when I bolted the other end. What I have now is one end of the bar secure with a lag bolt and a 5/8 inch hole in the marble and 1/2 inch hole in the block where the other end is supposed to mount.
I thought about piping in a stiff mix of thinset using a grout bag and then redrilling the hole and using a lag shield again but I just don't think it will hold up. I can probably get a butterfly anchor in the insulation space behind the drywall, but is this the best way to go?
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On 1/11/2013 2:48 PM, Dave wrote:

cultured marble slabs with drywall behind the marble and then a 1 inch or so space for insulation, and then block behind that. My plan was to drill into the block and use lag shields to hold the bar in place. This worked on one end of the bar but it seems the block split apart when I bolted the other end. What I have now is one end of the bar secure with a lag bolt and a 5/8 inch hole in the marble and 1/2 inch hole in the block where the other end is supposed to mount.

redrilling the hole and using a lag shield again but I just don't think it will hold up. I can probably get a butterfly anchor in the insulation space behind the drywall, but is this the best way to go?

thinset isn't strong enough.
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Bummer....
The problem with block.....kinda brittle & prone to splitting.
I recommend setting a threaded rod with an epoxy like http://www.lowes.com/pd_354677-286-862031_0__?productId=3416896 whenever trying to anchor into block.
Using the nozzle to reach through the gap you could flood the cracked block with epoxy paste to repair it & give you solid material to anchor to,
The nozzle might be a bit big in diameter but SIKA (Home Depot) makes a similar product with a smaller nozzle but it sets FAST.
Alternatively, you could set a coupling nut with one end threaded rod to generate a female anchoring thread. cheers Bob
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On Friday, January 11, 2013 10:47:03 PM UTC-7, DD_BobK wrote:

Brilliant!
I'm not worried about fast setting. All I need time to do is flood the hole and rod and put the rod in the hole.
I believe I'll do this on the other end of the hand rail as well. The project is for a stroke victim (who happens to be my mom) so I really don't want these things letting go.
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You can get two component epoxy resins for this purpose. Inject, let set, redrill.
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On Friday, January 11, 2013 1:48:25 PM UTC-8, Dave wrote:

What's on the other side of the wall?
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