this post was submitted on 19 Jan 2024
67 points (95.9% liked)
Asklemmy
43965 readers
1714 users here now
A loosely moderated place to ask open-ended questions
Search asklemmy π
If your post meets the following criteria, it's welcome here!
- Open-ended question
- Not offensive: at this point, we do not have the bandwidth to moderate overtly political discussions. Assume best intent and be excellent to each other.
- Not regarding using or support for Lemmy: context, see the list of support communities and tools for finding communities below
- Not ad nauseam inducing: please make sure it is a question that would be new to most members
- An actual topic of discussion
Looking for support?
Looking for a community?
- Lemmyverse: community search
- sub.rehab: maps old subreddits to fediverse options, marks official as such
- [email protected]: a community for finding communities
~Icon~ ~by~ ~@Double_[email protected]~
founded 5 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Hoover and three gorges dams. That much cement will be noticable for a long time.
"Low cost" levys and break waters, since those just use large cut rock dumped in the water.
A lot of modern engineering uses a more advanced type of cement than the ones ancient people used.
It's chemically stable so it doesn't react with the environment and has a predictable lifespan.
A side effect of this is that it predictably only reliably lasts about 100 years.
Older cement could react with the environment, which meant sometimes it broke really fast, but also sometimes it is able to heal small cracks and last indefinitely, if it doesn't get a mold outbreak.
The pyramids are basically a big pile of rocks, so that isn't going anywhere.
So for modern buildings, you'll want to look for structures made from cement intended to last a very long time with low maintenance near water, like the biggest dams, or things made out of cut rock, like low cost commercial port break waters.
We just don't make as many structures out of raw rock or crappy cement anymore, so it's not as likely for a lot of buildings to survive.
On the flip side, we do have a lot more buildings, so they'll probably find random elementary schools in Nevada in 4k years.
It's worth noting that steel reinforcements drastically reduce the possible lifetime of a concrete structure. It'll eventually rust which causes it to expand inside the concrete which will cause the concrete to crumble.
Being pedantic but itβs concrete not cement. Cement is one of multiple ingredients of concrete. Itβs a binder.
That's fair. I was thinking about the active part that causes the difference in lifespan while typing. :)