What is Concrete?
Why Hacker News recommends it
Commenters link it as an approachable explanation of concrete basics in threads about Roman concrete, construction and sand supply.
What it is
Practical Engineering gives a short introduction to concrete, covering the difference between concrete and cement, the ingredients, and reinforcement. It includes a hydraulic press demonstration of compressive strength.
Recommended by 2 HN commenters across 2 different months, 2018 to 2023.
What Hacker News said
Strong rec walty · 2023-01 · on “Riddle solved: Why was Roman concrete so durable?”
You're going to love this playlist from Practical Engineering [1]. Grady explains all of this much better than I could. The second video explains reinforcement and the fifth explains pre-stressing. [1] [this video]
Recommends zen_of_prog · 2022-07 · on “How the Colosseum was built and why it was an architectural marvel”
Concrete is made up of both cement (the CONtinuous part) and aggregate/stone (the disCRETE part), so cement vs concrete is kind of like broth vs soup, and concrete and stone like soup vs vegetables. > So the main difference is that you can shape it without chiselling it. I guess, yeah. Both are really good at withstanding compressive forces. Unlike Roman times, concrete today is usually reinforced with steel rebar, which gives it good tensile strength as well. This makes it useful for a lot of things that stone is not. Disclaimer, take everything here with a grain of salt. Continuous-discrete is not the etymology of concrete. This might help too: [this video]
Cites CGamesPlay · 2018-09 · on “Sand scarcity is about more than “running out” of sand”
I think that's basically plaster of paris? Practical Engineering did a good demonstration of different concrete ingredients: [this video]