5 ms·

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 w

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.

philipkglass 3y ago
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.
- fghorow 3y ago
  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. TANSTAAFL.
  - iancmceachern 3y ago
    So is digging it up and transporting it...
    - csin 3y ago
      You would have to transport it regardless. Whether it's crushed rock or sand.
      - iancmceachern 3y ago
        But how far? If you use old concrete from a building project in the city, crush it, then truck it 10 Miles to the new build site. If you get it from far away you could be trucking it thousands of Miles
MootheCat 3y ago
Selling sand to the Arabs is a thing. Their sand is too fine if I remember correctly.
- 1-more 3y ago
  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.
- Scoundreller 3y ago
  Fine weathered sand is great for drilling/fracking though. And sandboxes for kids.
eszed 3y ago
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?
- engineer_22 3y ago
  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.
  - lostlogin 3y ago
    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. The below link seems to agree. https://buildingadvice.co.uk/sharp-sand/ https://buildingadvice.co.uk/sharp-sand/
- gtvwill 3y ago
  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.
tda 3y 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
- c_o_n_v_e_x 3y ago
  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.
_boffin_ 3y ago
https://www.sciencedirect.com/science/article/abs/pii/S2352710223020235 https://www.sciencedirect.com/science/article/abs/pii/S23527...

philipkglass 3y ago

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.

fghorow 3y ago
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. TANSTAAFL.
- iancmceachern 3y ago
  So is digging it up and transporting it...
  - csin 3y ago
    You would have to transport it regardless. Whether it's crushed rock or sand.
    - iancmceachern 3y ago
      But how far? If you use old concrete from a building project in the city, crush it, then truck it 10 Miles to the new build site. If you get it from far away you could be trucking it thousands of Miles

MootheCat 3y ago

Selling sand to the Arabs is a thing. Their sand is too fine if I remember correctly.

1-more 3y ago
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.
Scoundreller 3y ago
Fine weathered sand is great for drilling/fracking though. And sandboxes for kids.

eszed 3y ago

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?

engineer_22 3y ago
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.
- lostlogin 3y ago
  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. The below link seems to agree. https://buildingadvice.co.uk/sharp-sand/ https://buildingadvice.co.uk/sharp-sand/
gtvwill 3y ago
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.

tda 3y 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

c_o_n_v_e_x 3y ago
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.

_boffin_ 3y ago

https://www.sciencedirect.com/science/article/abs/pii/S2352710223020235 https://www.sciencedirect.com/science/article/abs/pii/S23527...