Everyday for decades, a young man rides his bicycle, with a 10 pound bag of sand in tow, across a national border. This draws the attention of customs nearly everyday and they search through the sand day after day and find nothing.
Many many years later one of the customs agents sees the man, and asks if he was actually smuggling something all that time?
The answer was: "Yes, I was smuggling -- bicycles."
> Luis Fernando Ramadon, a federal police specialist in Brazil who studies extractive industries, estimates that the global illegal sand trade ranges from $200 billion to $350 billion a year—more than illegal logging, gold mining and fishing combined. Buyers rarely check the provenance of sand; legal and black market sand look identical. Illegal mining rarely draws heat from law enforcement because it looks like legitimate mining—trucks, backhoes and shovels—there's no property owner lodging complaints, and officials may be profiting. For crime syndicates, it's easy money.
> The environmental impacts are substantial. Dredging rivers destroys estuaries and habitats and exacerbates flooding. Scraping coastal ecosystems churns up vegetation, soil and seabeds and disrupts marine life. In some countries, illegal mining makes up a large portion of the total activity, and its environmental impacts are often worse than those of legitimate operators, Beiser says, all to build cities on the cheap.
this sounds like a really hard problem to fix. i see there are researchers trying to estimate mining levels by counting ships[1], but even if we're able to get a heatmap of the problem, there'd need to be an enormous amount of cooperation between nations to certify sand provenance. damn.
I wonder if there is any r&d around using cheaper/abundant (finer desert sand) for construction. Or if the sand racket is preventing that (feels ridiculous to write that but all this about black market sand is new to me). Way outta my wheelhouse so I'm not even sure why it would be bad for construction in the first place.
Mechanically crushed rock can be used in concrete in place of river sand. There's no danger of stripping the rivers bare of sand (or running out of materials to make concrete) in places that have a modicum of environmental laws and law enforcement. Sand theft operations plague places with weak rule of law, where there's free money to be made by stealing from the commons even when responsible ways to make concrete are only modestly more expensive.
Crushing rock is very energy intensive (Griffith theory of fracture mechanics).
It's much better to let Mother Nature crush the rocks through stream action. (Sort of hydroelectric, without the electric parts.) Your suggestion would only replace one environmental cost with a different one.
My understanding is that desert sand gets blown around by the wind, which (heh) sands it smooth. Smooth sand doesn't grip the concrete (I think), so it's not amenable for building.
When I first read that my question was whether a different concrete formula or amalgam could work with smooth(er) sand, or if that's a hard limit that cannot be overcome. Does anyone know?
Concrete strength is a function of several factors
Strength of Cement - portland cement is typically used. Fire limestone to get lime, add fly ash and other additives for increased strength. Ratio of Water to Cement is important to get a complete reaction, but dont add too much water.
Aggregate - angular aggregates provide the cement something to stick to and distribute the stresses evenly. You want a well graded aggregate, including sand particles up to larger chunks of rock.
In my part of the world the aggregate is typically crushed limestone. Add clean sand for different mixes.
There are other chemical additives that will increase strength, workability, and the speed of cure.
Since reaction of water to cement is exothermic - on the really high tech monolithic pours they're using technology to carry away the waste heat. You want the whole mass to be at the same temperature to reduce the internal stresses.
There are actually spherical glass orbs you can add to your concrete if you want it light-weight. Floating concrete is a thing. This comes at the expense of strength.
Adding to this, when making concrete, ‘sharp sand’ is preferable to ‘building sand’ as it’s chunkier. Building sand is more commonly used for mortar and gives a better finish. However this is a distant memory of what a brick layer was instructed me on when I was getting supplies for him a long time ago.
Generally, one of the main problems with geopolymer binder is its poor workability: Alkali-activated fly ash has a much greater plastic viscosity than ordinary Portland cement[31] and is prone to fast setting. In a matter of minutes, it can produce “highly viscous, unmanageable concrete mixtures”.[32]
These problems were faced with Portland cement as well, leading to the development of mix designs and admixtures that increase workability; to a limited extent, those techniques can be applied to geopolymer binder.
And in Roman times, concrete was laid in lifts like how foundation soil is handled today.
Yeah, it's more effort than just pouring a thick soup into a vibrating mould, but e.g. precast slabs could handle a non-pourable paste. The side effect of rapid hardening would also be rather easy to handle and even allows shorter mould cycle times (and thus afford more expensive moulds).
Another example would be railroad ties that could compression-mould. Those are produced in the millions per year.
What are the regulatory burdens around this? Is it simply that building codes only recognize Portland cement, and anything else is treated like you're trying to build with mud?
Yo it's cement + aggregate makes concrete. As in concrete is the sum of two or more products. Concrete doesn't grip anything. Cement binds and aggregate shape doesn't count for bugger all.
You use tie in rods of rebar to bind one slab to another, not the aggregate because the aggregate does sh*t all for structural strength. It's more for the compressive strength.
Tbh you can make a form or concrete out of perlite and cement. It's light af, great for ship hulls when reinforced with steel. Still concrete,just doesn't need any sand.
> Cement binds and aggregate shape doesn't count for bugger all.
This isn't true at all.
Using your example of rebar, this is why any piece of rebar has lugs down it; to bond better with the cement. If you use a smooth cylinder of steel, it won't bind to the cement as well and you wind up with a weaker finished product. The ribs of the rebar increase the surface area and make the rebar-cement bond stronger.
Same thing with desert sand. If you have rounded sand grains, you've got reduced surface area per unit volume, and thus reduce the strength of the bond between the aggregate and the cement. That weaker bond becomes a fracture point.
Thanks. Yeah, I've poured a few slabs and built a few walls, but construction engineering is waaay out of my normal competencies, so I appreciate the vocabulary corrections.
You say "aggregate shape doesn't count for bugger all". So why does river / crushed sand work, and desert sand doesn't? It sounds more like there are different aggregate mixes / types of aggregate material that work for particular applications (hadn't thought that through, but it makes perfect sense), and that "rough" sand is better for the most-common concrete use-cases. Do you know of specific types of concrete where "smooth" sand would be preferred?
Someone covers it further down. There's a whole bunch more to the strength of concrete than the aggregate.
Man last major concreting I did smooth sand would have been awesome. We were already trying to use the finest grade sand we could find. It was on mad max 4. Making concrete not look like concrete (think underwater caverns, cliffs, waterfalls). So smooth is awesome, makes it easy to texture to look like different types of weathered rock.
All the structural strength was from steel rebar with chook mesh wired to it. The crete and scratch coats were about 100mm thick at the most.
too smooth too. Windblown desert sand has smooth grains that won't adhere inside of the concrete mix. Sand grains from water have been slowed down by the water when hitting one another, so the grains have jagged parts. At least according to a thing I read about this years ago.
I once was involved in project where 60M m3 of sand was pumped to the desert from the sea. It felt totally insane; all that sand was dredged from the sea, mixed with a ton of water and then pumped for some 5-15km using up to 6 5MW pumps in series. Look for Al Zout refinery in Kuwait
I worked on an Exxon project on Jurong Island in Singapore. Today, Jurong Island looks like one singular island but it used to be a series of islands that were reclaimed. It was amusing seeing an old ship cleat in middle of the plant, hundreds of meters from any nearby water.
The landmass of Singapore itself has grown by 40% since the 60's through reclamation. There's always been lots of rumors about how the sand was sourced from neighboring countries.
Well, that'd have to be something that reacts with concrete that doesn't react with water, or plants in any way, something that isn't harmful to the animal ecosystem in the sand, or even the bacterial ecosystem so no big ph swings, and then you have to evenly distribute this product into a near infinite volume of sand.
So on the one hand it's an impending ecological disaster, and on the other its an economic catastrophe
All fair points except the one about "evenly distribute into a near infinite volume of sand", which makes no sense since you would obviously target the zones being used by the crime rings themselves, of course you can't find them all but if the risk of mining useless sand becomes big enough it may stop being economically attractive for those criminals.
So to apply your solution, assuming there is such a product and it has zero negative impacts, we'd need first find an illegal mining operation with certainty and reach it with a lot of man power. Which is the bottleneck in enforcement in the first place.
This was one of the plot points of a Barry episode (https://m.imdb.com/title/tt27052797/) where two characters (legally) obtain sand for construction purposes and turn it into a business to whitewash their criminal past.
It really is. It's a fantastic show. The latter seasons did change a bit but that's the whole point of it. Well done by Hader and team. The end of it was wild.
When I ended up in the tugboat business I was surprised to learn that there are markets for sand in both directions between Florida and The Bahamas.
We export some types of sand from Florida to The Bahamas for use in concrete construction. We import other types of sand from The Bahamas to Florida for use in aquariums.
For a good book on the non-renewable (on human time scales) resource of sand, see The World in a Grain: The Story of Sand and How It Transformed Civilization by Vince Beiser:
> The World in a Grain is the compelling true story of the hugely important and diminishing natural resource that grows more essential every day, and of the people who mine it, sell it, build with it--and sometimes, even kill for it. It's also a provocative examination of the serious human and environmental costs incurred by our dependence on sand, which has received little public attention. Not all sand is created equal: Some of the easiest sand to get to is the least useful. Award-winning journalist Vince Beiser delves deep into this world, taking readers on a journey across the globe, from the United States to remote corners of India, China, and Dubai to explain why sand is so crucial to modern life.
> The problem lies in the type of sand we are using. Desert sand is largely useless to us. The overwhelming bulk of the sand we harvest goes to make concrete, and for that purpose, desert sand grains are the wrong shape. Eroded by wind rather than water, they are too smooth and rounded to lock together to form stable concrete.
> River sand is preferable to coastal sand, partly because coastal sand has to be washed free of salt. But coastal sand does get used, especially when builders take shortcuts, leading to buildings that have shorter life spans and pose greater risks for inhabitants.
Wow, that's all the article said about this? It's the crux of the matter.
Corrupt chinese construction projects may use cheaper coastal sand, resulting in so-called "Tofu-Dreg" buildings (豆腐渣工程) where the salt in the sand has corroded the rebar and the building just falls down. As I understand it, it's a major concern in China. Google for it.
I was wondering about this after a recent beach trip I took. I won't name where I was, but I noticed a considerable improvement in sand quality on the beaches in front of the nice hotels. It was a quality difference that went beyond normal beach cleanup. Perhaps the sand was sourced locally, and beach improvement surely pales in volume to construction use of sand, but still it was the first time I'd wondered about sand mining/theft.
Regions that depend on tourism spend a lot of money on their beach sand. Even San Diego, CA where tourism is probably not even top 10 of industries by revenue, they replenish the sand that gets eroded every few decades. The process just started on the northern beaches: https://www.nbcsandiego.com/news/local/long-awaited-sand-rep...
They ship it in by sea on huge barges that are quite something to watch.
> They ship it in by sea on huge barges that are quite something to watch.
Not shipped in, pumped in: The source is less than a mile offshore, overlying a reef that supported lots of marine life, much of which is now being picked over by seagulls.
The hope is that friction and inertia will prevail for a few years against wave action and gravity. But, the project has its nose in the trough provided by the national and state taxpayers, and local politicians go along.
> tourism spend a lot of money on their beach sand
Not a factor in Solana Beach, the Chamber of Commerce is utterly supine on public policy issues. Rather, it's the owners of houses on the bluff top, where prices start in the high 7 digits, who drive beach policy: they all have, or want to construct, concrete armored seawalls. Like these:
With an effectively unlimited legal budget to invent ways around the law and litigate against the Coastal Commission, and willingness to mob City Council meetings, incumbents keep their mouths shut. Local resistance has collapsed down to a few die-hards at environmentalist groups, e.g. https://sandiego.surfrider.org, fighting what amounts to a retreating action.
Due to a recent storm in San Diego, large swaths of Mission/Pacific Beach houses and the boardwalk were left with tons of sand all over them.
The city scoops up the sand off the boardwalk and loads it into trucks which take it a few miles away to Fiesta Island.
Why? Apparently it is contaminated badly enough by whatever is on the boardwalk, that they don't want to just push it back onto the beach (and back into the water).
Sargassum Seaweed is usually what washes up to shores and makes beaches ugly. Resorts in the Mexico and Caribbean regions get a lot of it ashore, but there are now industries that use the seaweed as a building material.
Sargablocks[1] are one of the companies that are turning sargassum into cheap building materials
Playa del Carmen replenishes its beaches every few years. If you go at the wrong time, the beaches are like 7 meters wide, come back six months later and they are 30 meters wide.
At what point does it become feasible to just manufacture sand? I know it is possible but how much more expensive must sand get before we just convert quartz mountains into sand? The article's quoted "50 billion metric tons" of needed sand isn't all that much when compared to the weight of actual mountains.
Depending on the type of rocks and how fine you want to grind them, the Specific Energy used is between 10-100(kWh/t). That leads me to guess $8-$25 per ton of electricity used for grinding rocks into sand. I was unable to find good numbers for the capital cost.
At an aggregate mine located in Brazil, the total expenses are $80-$160 per ton [1].
The price of sand at home depot is 5.96 for a 50lb bag, $238 per ton. My conclusion is you could make sand by grinding but it would cost 50%-100% more vs. digging up the beach.
Land vs water/barge transport costs for bulk cargo may increase that by magnitude. Article suggest there will be 5x increase in demand and 5x increase in price at current stagnating availability. So that seems maybe doable.
I think this might be case where cheap deposits are obviously geographically constrained. River sand near shores/blue water access for bulk transport to global markets. Once you expand to exploring/exploiting increasingly inland, the logistics of bulk cargo starts stacking up.
I think, unqualified speculation, transportation cost scales linearly because most economical exploitation past shores is along river/waterway sand, hence exploitation will be not be squared. Squaring coverage territory, as in getting sand from land introduces land shipping, which is even less efficient because cost per distance is subject to geography. Unless, engineered sand comes from coastal infra that takes regional inputs and pipes it strait onto barges, which also makes sense. But wild speculation on my part.
There are many different types of sand for many different purposes. Sand for silicon is the most expensive. Sands for construction tend to be very cheap.
I don't think glass is appropriately pure for silicon - but that would probably be the only application for sand where it could possibly be economical to manufacture rather than extract and process.
Quite a bit, it's expensive to turn rocks into sand. Seems plausible that mines will start selling off their sand (after whatever they are mining is removed).
It is not. We have an unlimited amount of desert sand available to us, but we need the river sand for construction. Otherwise the likes of Saudi Arabia would be exporting sand instead of importing it for their sky scrapers. The same is true for the mining sand, only a portion of it is appropriate for construction.
'Just' pressure is not the only metric; from your link:
> However, the flexural and tensile strengths tended to decrease as the amount of desert sand increased, particularly beyond a 25% replacement level.
So it is not a 1:1 replacement, and there are further considerations that need to be taken into account into how much (if any) desert sand can be put into a particular mix for a particular purpose. Another paper if you want to get into the weeds somewhat:
> In this paper, the effect of DSRR, temperature and cooling regime on the mechanical performances of concrete produced with desert sand was analyzed. To study the influence of temperature on the microstructure of concrete produced with desert sand, the microscopic experiments (XRD, SEM) were employed.
Because existing organisation's would lose their profits from sand mining?
Nfi there's plenty of old wives tales from before the time when you could google it and be like "oi gran your talking sh*t" that effect how we do business today. This is probably one of them?
> Because existing organisation's would lose their profits from sand mining?
I'm willing to be cynical and conspiratorial, but this doesn't add up for me. There are so many players between "large construction firms in the USA" and "sand mafia in India" that I find it hard to believe that this is the action of a global cartel. Unless large construction firms in the USA specifically are also run by the sand mafia, which of course is possible, but would be a hell of an exposé if anyone ever caught on.
We really don't. The majority of desert is not sand. Only around 20% is sand, and around 3% consist of sand dunes.
Transportation in deserts is complex due to the rocky terrain that usually fills the rest of the desert.
It is economically cheaper and easier to take beach and river sand. (Especially since some countries designate sand dunes as protected areas)
Leftover sand from mineral mining might be better for concrete. As “fresh” sand it’s probably nice and jagged-y, but maybe so fresh without weathering that its weak points haven’t broken off yet.
A friend of mine lives in Argentina. It's a nice place to live... Except in the second tier city he lives in, they steal everything. He had a bag of sand for mixing concrete with that was left outside. As soon as it was emptied enough for a single person to lift, someone stole the bag of sand.
The main bar chart [1] seems at first shocking, then deceptive. Bar height is illegal $ transacted, but there is no multiplier for moral repugnance or "just how illegal is each $". Surely $1 transacted in illegal human trafficking is far worse than $1 transacted in illegal sand trafficking.
Back in middle school, there was MC server drama over people stealing sand from around people's houses. And every big build involved destroying some nearby island for its resources.
I remember some server that basically existed as a work camp for the builder owner. They were accumulating cobblestone to recreate a 1:1 minas tirath. They would provide diamond tooling and you’d just mine and fill certain chests for them with cobble. The other resources you’d find served as your payment.
The same day we have an article about a Chinese property company going bust who overdeveloped. All that sand is just sitting there in those buildings now.
Many youtube videos demonstrate how crappy these deliverables can be built. "Tofu Dregs" is how this building method is referred, for anybody searching.
We have to think what the alternative is... Either not build things with concrete... Or buy sand from other places which probably have corrupt officials willing to issue sand extraction permits without much thought.
Also... Sand is expensive (in money and in environmental impact) to transport.
In the face of this I give up trying to identity business opportunities. Stealing sand to sell on the black market? Hundreds of billions in revenue? I’m out - I clearly suck at this capitalism thing.
Everyday for decades, a young man rides his bicycle, with a 10 pound bag of sand in tow, across a national border. This draws the attention of customs nearly everyday and they search through the sand day after day and find nothing.
Many many years later one of the customs agents sees the man, and asks if he was actually smuggling something all that time?
The answer was: "Yes, I was smuggling -- bicycles."