Fill cinder block cavity with concrete to reinforce broken foundation?

[austin]

Would it be a good idea to fill cinder block cavities with concrete to reinforce a broken foundation where three above grade blocks (alternate rows) have cracked through vertically? I have access to the cavities from the top from the inside of the house.

[pushkins]

It will make little difference to the strength of the wall. Core filled walls are done so at build and almost always have reo rods running up through them to "tie" all layers together and the concrete placed in side the core is vibrated to settle to concrete without air pockets, thus tying it all together. In your case the blocks are not moving apart from each other but moving as a whole section together.

[austin]

I thought I would drill holes horizontally from the outside corner of the foundation and insert reo bar to the other side of the crack to tie it all together. Or would that risk causing more cracks? Since I have access to the top of the cavities from inside the house, I thought I would be able to either tap down the concrete as it's poured in, or vibrate it. I haven't poured concrete before. What is the diameter of a vibrating probe?

[pushkins]

You could do that, but it would be a brave man that hammer drills through cracked cinder blocks and you'd need at least a 12" bit to drill through the 8" cinder block and then through the other blocks wall just to find the cavity and that's before taking into consideration the gape length and the chuck hold length. The cracking of the blocks would be a far bigger issue though, one I'm sure I wouldn't attempt in your situation especially on the corner like that.