I imagine that water over the years infiltrating that block has damaged it. The freeze-thaw cycle is tough on concrete or masonry that has ingested water.
From the pictures, the block looks pretty badly damaged. I would bet that it is softened to the point that exposed areas are easily scraped off, right?
If there is a way water is getting in/on the blocks, deal with it first. If the blocks are all as degraded as they look, I don't imagine there is anything you can do that would be better than a very temporary repair. A foundation company would probably need to be consulted to make repairs.
Yes, you are correct about it scraping off. I can take a lot of the concrete off by kicking it. Would it be more cost effective to replace or repair? Also, it is only on the front porch not on the foundation of the house itself. I was considering knocking out the old blocks and replacing them with new.
Last edited by thunderdelblanco; 06-17-2008 at 02:56 PM.
If it is that soft, I don't see repair (such as patching the holes) as an option. Replacement will be your best bet. It is easy for me to say that having seen a couple pictures on the computer, so I still suggest you consult a professional that can give it a thorough evaluation.
If much of the walls still are sturdy, replacing individual damaged blocks may be a good option for you.