Sand scarcity is about more than “running out” of sand | Hacker News Reader

Sand scarcity is about more than “running out” of sand

theverge.com

71 pointsTomte37 comments

Making sand by grinding down rocks is routine in the developed and semi-developed world. The trick was developing a method of rock crushing that mostly crushes rock against rock, rather than rock against steel. That's the vertical shaft impact crusher. Wear is much less, the product quality is better, and power requirements are lower. Lots of videos of this available, if you like rock crusher videos.

That's something that will probably become more and more commonplace. It's a few times more expensive (I can imagine) than just digging up existing good quality sand though.

But it's a more-or-less constant cost (energy costs, maintenance, rock supply), vs rising costs of sand (diminishing sand reserves, increasing shipment costs).

Could you make sand from rock with water jets?

Things I learned: River sand is the best type of sand to use in Concrete. There a companies that manufacture sand. Desert sand is too fine to work well in concrete. There are "sand mafias" in India stealing entire riverbeds of sand.

Things I didn't learn because they 'didn't have enough time to talk about it in the video': the environmental aspects of harvesting this sand.

I am amused when YouTube video presenters claim they didn't have enough time in their film to include a key important aspect. In the days of broadcast TV programmes would have a fixed time slot and some content might have to be edited out or not covered. Rarely did any presenters say 'not enough time' though. But on YouTube where there is 'plenty of time' and a video does not have to be a particular length, people do claim 'not enough time', to make you watch ~10 minutes to learn nothing much beyond how you must like and subscribe to their channel.

Video file length is not the type of time they ran out of.

To present a topic properly takes much more time than the 2 minutes you see in the video.

>>Things I learned: River sand is the best type of sand to use in Concrete.

If it's washed and clean of dirt...maybe. But crushed stone IMO is even better, it's not round and thus performs better in earthquakes.

>But crushed stone IMO is even better, it's not round and thus performs better in earthquakes.

Maybe if you manage to pump the concrete with a reasonable wear to the equipment, you mean.

Normally with crushed sand you need to increase cement quantities (because more water is needed) and need finer fillers like "flying ashes" and since you dont' want to have excessive resistance and thus excessive shrinkage, you need also other chemical additives.

And - just for the record - rounded aggregates tend to make stronger concrete, not the other way round, not because of the "surface", but because of the "shape", a concrete made of only spherical (in theory) aggregates has the less voids, and the more the actual shape of each aggregate tend to be similar to a sphere the less voids you find in the mix (that need to be filled by smaller fillers).

Of course this is "generally speaking", concrete is a product not much different from cooking, you need good ingredients, a good recipe, good equipment and a good cook to have a valid result.

How to read this headline:

"scarcity" -> "cost"

"is about more than" -> "is about"

"running out" -> "local availability"

Thank you. That saves me the bother of reading the article.

The article is functionally a wordier version of "watch the video" anyway.

Yes, there is no article there. I hate that. There's no audio in my VM, for various reasons, and CC (if even there) is an utter waste of time.

Yes, it's a video. How is that a reason not to submit it? How is your misconfiguration a reason to complain?

Probably should have a [video]-tag if so. There are also plenty of other situations where one is unable or where it is cumbersome to be able to listen to audio.

Very helpful, thank you.

I don't get the reasoning. Unweathered sharp sand has more surface area than stuff that has been tumbling in water for a long time, no? In my experience the received wisdom is, that glacial esker sand, sieved, is good for concrete. Somewhat like the manufactured sand.

But I might very well have misunderstood, or the old folks advice might not be right. Or it does not scale to industrial uses.

And this is why I don't watch videos. 7+ minutes for the same amount of information I could have skim-read in under a minute.

Same here. But in its defense, there are lots of cool images, and I can imagine how the author decided that a video was best. I'd have preferred a slide deck, but whatever.

get a video speed plug-in for your browser and watch HTML5 videos at 1.5x or 2x. It's changed my life.

Tried it. Weird and still slower than reading.

Plus I don't want to pander to the internet's decline into a glorified tv channel. If they can't write a blog post then to hell with them.

Is it beyond our capabilities to come up with a new composition of concrete that involves finer grains of sand?

Maybe it is not as strong, but it seems like necessity should involve some compromises.

I've thought the same thing every time I read a sand article. Surely this is a promising field in materials science, but I never hear anything about it.

I think that's basically plaster of paris? Practical Engineering did a good demonstration of different concrete ingredients: https://www.youtube.com/watch?v=UOHURuAf5iY&vl=en

Plaster of Paris is a different cement than the Portland Cement mostly used in concrete.

A big difference is that it isn't waterproof.

It's pretty easy to increase the grain size of a material - ceramics processing does it all the time with spray dryers. The problem comes down more to a) composition and b) cost of processing. Sand is highly naturally refined - rivers and the ocean break down almost everything but silica, and the entire erosion process acts like one giant particle size sorting machine. "clay" and "silt" etc. are purely descriptions of size; they can vary widely in chemical makeup, and most of those variations will negatively impact concretion.

A push to switch over to manufactored sand would work well enough. I'm sure once the technology improves and the big players successfully vertical integrate it into their own process than the demand for natural will drop, like what happened with paper companies switching over to their own tree plantations over harvesting random forest

Different grains sizes and shape effect strength. There are different grades of concrete. So while it might be acceptable for some things. Moreover any major civil engineering project is going to make sure a proper Sieve analysis is performed on all the concrete filler material. to make sure it conforms to the requirements.

>new composition of concrete that involves finer grains of sand

i think the new building technologies based on 3D printing may be an opening for the finer grain sand.

perhaps some kind of solar pairwise sintering?

The information content of the video might be not too big - it boils down that river sands, which are the best for concrete are somewhat scarce. But it is worth while watching it, as towards the end they show microscope takes of the different kinds of sand being talked about. Those takes clearly show nicely how different the artificial, river and sea sand are with some faszinating imaginery. So this is a case, where the video adds to the textual information. Though it takes a while till it gets to the really interesting part.

I feel like I'm missing out on something here: https://snag.gy/hDjiEF.jpg

Disabling the ad blocker doesn't work. Anyone else having this?

No, in fact for me the text seems to load first and then other elements of the page load around it. And I'm running HTTPS Everywhere, Privacy Badger, and Decentraleyes in addition to uBlock Origin (with mostly-stock blocklists), so if there's going to be an issue I usually hit it :p

Edit: if you click the Readability Mode icon you should at least be able to read the text. Here is the video: https://www.youtube.com/watch?v=V2349cn0-T0

Readability doesn't work for me either, same short piece of text. Checking the error console, only a warning for some script of LinkedIn that didn't load, and all the network requests succeeded. Odd. You'd think if it's supposed to load dynamically (why'd you want to do such a thing anyway? It's not as if the text is as big as a JS library and they don't mind including those), it would at least throw an error if something failed.

That's all there is. It's just the lead for the video.

Oh! Now I get it, thanks.

I learned in school that silicon is literally the second most common element on Earth.

So this story sounds like fake news to me.

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