Can I use old concrete block in new construction project?
May 23, 2017 10:16 AM Subscribe
Can I use concrete blocks that have been sitting out in the open for 20-50 years in a foundation?
I have to repair the foundation in a very remote sharecropper's cabin that is currently unoccupied.
On the property there are enough concrete blocks that have been sitting out for anywhere from 20-50 years. They are in good shape and haven't been used - just leftovers out in the open.
Can I use these in load-bearing foundation walls if I clean them up, or is there a problem with the weathering they have been going through?
I've tried to google, but I don't want to recycle them or use them for retaining walls.
I have to repair the foundation in a very remote sharecropper's cabin that is currently unoccupied.
On the property there are enough concrete blocks that have been sitting out for anywhere from 20-50 years. They are in good shape and haven't been used - just leftovers out in the open.
Can I use these in load-bearing foundation walls if I clean them up, or is there a problem with the weathering they have been going through?
I've tried to google, but I don't want to recycle them or use them for retaining walls.
As far as I know, the main structural problem with weathered concrete is the possibility of chemistry changes that attack embedded steel reinforcing.
Concrete blocks don't contain steel reinforcement, so if they haven't been exposed to sulphates or sulphides (heavily polluted rain or sewage, essentially) the only things that weathering will do to them are (a) etch their surfaces a bit and (b) turn some of the cement to limestone, which actually makes it harder. I think you'll find that both these effects make your weathered blocks into better foundations.
Wikipedia's article on concrete degradation is not too bad.
posted by flabdablet at 10:40 AM on May 23, 2017 [1 favorite]
Concrete blocks don't contain steel reinforcement, so if they haven't been exposed to sulphates or sulphides (heavily polluted rain or sewage, essentially) the only things that weathering will do to them are (a) etch their surfaces a bit and (b) turn some of the cement to limestone, which actually makes it harder. I think you'll find that both these effects make your weathered blocks into better foundations.
Wikipedia's article on concrete degradation is not too bad.
posted by flabdablet at 10:40 AM on May 23, 2017 [1 favorite]
Concrete continues to harden 'forever'. As long as they haven't been attacked by acids/pollution, and as long as the local code doesn't require 'certified/specific type' concrete blocks, you should be fine.
posted by mightshould at 11:25 AM on May 23, 2017 [1 favorite]
posted by mightshould at 11:25 AM on May 23, 2017 [1 favorite]
Response by poster: Thanks, everybody.
I thought that was the case, but wanted to check and see if there was something I was missing. I really appreciate it. When I'm done, you are all invited down for frog legs and crawdads!
posted by Tchad at 11:32 AM on May 23, 2017 [1 favorite]
I thought that was the case, but wanted to check and see if there was something I was missing. I really appreciate it. When I'm done, you are all invited down for frog legs and crawdads!
posted by Tchad at 11:32 AM on May 23, 2017 [1 favorite]
Think about it this way: Plenty of buildings are standing around with concrete block foundations that are well over 20-50 years old. Some more than 100 years. So your blocks should be fine.
posted by beagle at 4:08 PM on May 23, 2017 [1 favorite]
posted by beagle at 4:08 PM on May 23, 2017 [1 favorite]
While that's a fiar observation and I agree that Tchad won't have any problems with their blocks the buildings whose blocks have failed aren't around for us to use as a counter example.
posted by Mitheral at 11:44 AM on May 24, 2017 [1 favorite]
posted by Mitheral at 11:44 AM on May 24, 2017 [1 favorite]
This thread is closed to new comments.
It's been standing right where I put it for something like two years now fwiw.
posted by cmoj at 10:40 AM on May 23, 2017