Do concrete blocks lose strength over time?

[mwhutch]

This may be a dumb question but I am wondering if concrete blocks will lose strength over time if left out in the weather?  For example a year? Would you still feel comfortable using them for a crawlspace foundation?

[JRR]

I would have not problem using them as long as water had not frozen in them.  Installed blocks: building walls, foundations, etc, etc, .... are exposed to the weather all the time .... so un-installed blocks should do as well if they get the same protection from freezing.  How well can they be cleaned and prepared for mortar is another question.  ??

[mwhutch]

Those are really good points that I didn't think of.  We had a very mild winter here in South Carolina, so that is positive. I think ideally they would have been covered! Someone down the road has a bunch they had planned to use to build a garage and changed plans. They are selling them for $0.75 a piece, which would be a good deal if their structural integrity hasn't been compromised. I need to ask them where they have been stored then. Thank you for your quick response!

[roadtripray]

I think the key (as JRR said) is that water had frozen IN them.  Not that the blocks had been subjected to freezing water.  Because obviously a block foundation is subject to freezing all the way down to the frost line. 

I'm not sure, but it seems you should be able to visually inspect the block for cracks.  The way those are made they are pretty easy to split, so I don't think they would hide a crack very well -- at least not for long.