Bricks, Masonry, Asphalt and Concrete - Does cement mix expire?

When we bought our house 12 years ago, there were several bags of concrete stacked up in the back of the garage and, well, they're still there. The house was vacant for a few years before we moved in, so our best guess is that the concrete mix is at least 15 years old (it could even be 20 or 30 years old as far as we know). The bags are very dusty, but not torn open and not hardened (no signs of water having ever gotten on them).

Does this stuff expire or is it okay to use if it's still powdery? We were thinking about using it for a small section of sidewalk and curb we had to bust up for a rain water drain pipe project we're in the middle of.

I had a bag of mortar mix lying around for years and when I tried to use it later (fewer years than yours) it would not harden!

My guess is that the cement powder used in the mix lost its bonding properties slowly over time. So what I'd suggest is that you do a test on the stuff you have before you throw it out. Take a bit of the stuff you have, mix it with some water and leave it to see if it hardens. If it does, you're good to go. My guess is that it won't.

It doesn't expire, but it does abosrb moisture from the air and set. With low moisture it is possible that it could set in particulate fasion instead of turning into a rock. It is too cheap to bother with anyway.

Thanks for the replies. It sounds like it's best to just leave the old stuff be. One day we'll find a way to get rid of it :rolleyes: