5 ms·
Re concrete, I’ve been hearing a lot that we are running out of sand (the kind we make glass out of and the kind we make concrete out of). Is that true? Anyon
by thedudeabides5 7y ago
Re concrete, I’ve been hearing a lot that we are running out of sand (the kind we make glass out of and the kind we make concrete out of).
Is that true? Anyone have numbers/research on sand that’s good?
- mdorazio 7y agoDepends who you mean by "we". Seems there are regional shortages [1], but the US only hits supply constraints occasionally. [1] https://www.smithsonianmag.com/science-nature/world-facing-global-sand-crisis-180964815/ https://www.smithsonianmag.com/science-nature/world-facing-g...
- rapnie 7y agoAlso discussed on HN: https://news.ycombinator.com/item?id=15739917 https://news.ycombinator.com/item?id=15739917
- imtringued 7y agoThere is an abundance of sand away from the construction sites but transportation is too expensive so regional suppliers are preferred.
- logfromblammo 7y agoThough it seems like it might be easier to ship sand for pre-stressed concrete crossties, given that all the materials must necessarily be connected to the rail network. Also, I wonder why concrete crossties don't use neoprene bearing pads under the rails to reduce the abrasion problem.
- simonrobb 7y agoAre concrete crossties pre-stressed? It makes sense now I think about it, but I'm just surprised more effort than "pour concrete into a mold" goes into such an unassuming structural member.
- logfromblammo 7y agoI'd guess that poured concrete is not cost-competitive with timber crossties, and pre-stressing is the only way to make them cheaply enough to compete.