Crumbling blocks in porch foundation

Old 06-07-09, 07:46 AM
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Crumbling blocks in porch foundation

My porch has a concrete slab on a block foundation. The first two courses are 8" blocks and the top one is 4". Many of the 4" blocks are disintegrating. They are basically turning to powder. I have reinforced this area with jack screws to hold up the slab in the areas that are the worst. The 8" blocks are not showing the same symptoms. What is the best procedure of replacing the top course where needed. It seems like I could get a new top course in but I don't know the technique for getting mortar in the joints properly or what materials would be best to use.

Thanks in advance

Old 06-19-09, 09:26 AM
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the 4" block should be replaced with 8" block.

are the 8" block courses filled with concrete?

and i assume the block is laid on a good footing.
Old 06-19-09, 09:45 AM
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Are we talking 4" hollow block on its side? If so it needs to be replaced with #1 solid cap blocks. The blocks may also have been landscape blocks. These should not be used.

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