How to: Build a better sand castle
http://boingboing.net/2013/04/24/how-to-build-a-better-sand-ca.html

Geoscientist Matt Kuchta explains why wet sand makes a better castle than dry sand — and what you can do to make your sand fortress even more impenetrable. Hint: The secret ingredient is window screens.

however this article from one of the comments says window screens are not necessary

http://www.sandscapes.com/sandtech.html
The “Big Secret”
In a word the big secret is “friction”. More specifically, the sum total of all friction between the grains acting on each other. This is why compaction is so important. When you compact sand you increase the friction between the grains.
Uncompacted sand has relatively large pore spaces between the grains but compacted sand shrinks these spaces increasing points of contact between the individual grains and thereby increasing the friction between them. The more friction there is, the more resistant the grains are to separation.

more…

CrazyNeutrino said:

How to: Build a better sand castle
http://boingboing.net/2013/04/24/how-to-build-a-better-sand-ca.html

Geoscientist Matt Kuchta explains why wet sand makes a better castle than dry sand — and what you can do to make your sand fortress even more impenetrable. Hint: The secret ingredient is window screens.

however this article from one of the comments says window screens are not necessary

http://www.sandscapes.com/sandtech.html
The “Big Secret”
In a word the big secret is “friction”. More specifically, the sum total of all friction between the grains acting on each other. This is why compaction is so important. When you compact sand you increase the friction between the grains.
Uncompacted sand has relatively large pore spaces between the grains but compacted sand shrinks these spaces increasing points of contact between the individual grains and thereby increasing the friction between them. The more friction there is, the more resistant the grains are to separation.

more…

Hmm, I’ll go and have a look when I have time, but initial comments are:

Friction alone is not enough, you can’t make a vertical wall out of dry sand, no matter how much friction it has. You need some cohesion, which is what the water provides.

The window screen sounds like they are constructing some reinforced soil, a widely used technique for constructing retaining walls and steepened slopes in Australia and throughout the world. In real applications the reinforcement may be provided by fabric sheets, plastic strips, or galvanised steel strips.

>Friction alone is not enough, you can’t make a vertical wall out of dry sand, no matter how much friction it has. You need some cohesion, which is what the water provides.

That’s explained in the video, which is sensible enough, but not terribly exciting.

Bubblecar said:

>Friction alone is not enough, you can’t make a vertical wall out of dry sand, no matter how much friction it has. You need some cohesion, which is what the water provides.

That’s explained in the video, which is sensible enough, but not terribly exciting.

The first video is OK. The second link was misleading.

Bubblecar said:

>Friction alone is not enough, you can’t make a vertical wall out of dry sand, no matter how much friction it has. You need some cohesion, which is what the water provides.

That’s explained in the video, which is sensible enough, but not terribly exciting.

You’re dragging me back to my years in the triaxial lab. c and phi.

>The first video is OK. The second link was misleading.

Ah. I didn’t go there.

CrazyNeutrino said:

How to: Build a better sand castle
http://www.sandscapes.com/sandtech.html
The “Big Secret”
In a word the big secret is “friction”. More specifically, the sum total of all friction between the grains acting on each other. This is why compaction is so important. When you compact sand you increase the friction between the grains.
Uncompacted sand has relatively large pore spaces between the grains but compacted sand shrinks these spaces increasing points of contact between the individual grains and thereby increasing the friction between them. The more friction there is, the more resistant the grains are to separation.

more…

So, the really big secret is actually particle size distribution. A well graded sand will compact better than a poorly graded sand.

When the class began, wordlessly he picked up a very large and empty glass jar and proceeded to fill it with coarse gravel. He then asked the students if the jar was full. They agreed that it was.

The professor then picked up a jar of fine gravel and poured them into the jar. He shook the jar lightly. The fine gravel, of course, rolled into the open spaces between the coarse gravel. He then asked the students again if the jar was full. They agreed it was.

The professor picked up a box of sand and poured it into the jar and of course the sand filled up everything else. He asked once more if the jar was full. The students responded with an unanimous yes.

The professor then produced two cans of beer from under the table and then proceeded to pour the entire contents into the jar, effectively filling the empty space between the grains of sand. The students laughed.

“Now,” said the professor, as the laughter subsided, “I want you to recognise that this jar represents your life. The coarse gravel is the important things — your family, your partner, your health, your children, your friends, your favourite passions — things that if everything else was lost and only they remained, your life would still be full.

“The fine gravel is the other things that matter, like your job, your house, your car. The sand is everything else — the small stuff.

“If you put the sand into the jar first,” he continued, “there is no room for the fine or the coarse gravel. The same goes for your life. If you spend all your time and energy on the small stuff, you will never have room for the things that are important to you. Pay attention to the things that are critical to your happiness. Play with your children. Take time to get medical checkups. Take your partner out dancing. Play another 18.

“There will always be time to go to work, clean the house, give a dinner party and fix the disposal. Take care of the coarse gravel first — the things that really matter. Set your priorities. The rest is just sand.”

One of the students raised her hand and inquired what the beer represented. The professor smiled. “I’m glad you asked. It just goes to show you that no matter how full your life may seem, there’s always room for a couple of beers.”

I thought the secret was to use ‘fatty’ sand, which (I think) Is full of Clay, poured into rough forms (like Concreters use) and compact the shitter out of it with a petrol-driven whacker machine. Seems to be what the competition sandsculptors do.

Rule 303 said:

I thought the secret was to use ‘fatty’ sand, which (I think) Is full of Clay, poured into rough forms (like Concreters use) and compact the shitter out of it with a petrol-driven whacker machine. Seems to be what the competition sandsculptors do.

Great tips for the sand castle building inclined.

http://www.environmentalgraffiti.com/travel/news-great-mosque-djenne-largest-mud-brick-building-earth

ms spock said:

Great tips for the sand castle building inclined.

+ nods +

You can buy fatty sand as ‘Brikkie’s Sand’ at sand / stone suppliers everywhere. Very different stuff to normal sand, in case you’re not familiar with it.

Glance Fleeting said:

http://www.environmentalgraffiti.com/travel/news-great-mosque-djenne-largest-mud-brick-building-earth

I question the claimed environmental credentials of things like this. How much land is needed to grow the straw? How’s the labour compare to modern bricks? how’s the insulation compare to double brick with some pink batts in between for a similar thickness or mass?

The whole argument for things like this seems to be “it’s ancient and simple and hippies can do it in their backyard!”

Rule 303 said:

ms spock said:

Great tips for the sand castle building inclined.

+ nods +

You can buy fatty sand as ‘Brikkie’s Sand’ at sand / stone suppliers everywhere. Very different stuff to normal sand, in case you’re not familiar with it.

• nods and takes notes *

to make a structurally sound sand castle without using some environmentally unsound product is to mix some flour in with the wet sand to make a glue, that is the sand castles sand grains are sticky.

flour is cheap and when the tide comes in will just wash away with no problems, it shouldn’t attract flies either.

to make a structurally sound sand castle without using some environmentally unsound product is to mix some flour in with the wet sand to make a glue, that is the sand castles sand grains are sticky.

flour is cheap and when the tide comes in will just wash away with no problems, it shouldn’t attract flies either.

There is a blending formula to achieve the maximum packing with sand. I have made up mixtures that included material right down to colloidal size using this formula. The .45 power rule or somesuch. The resulting mixtures can be made to flow like honey.

Sand sculptures
http://imgur.com/a/pFNkc

more sand sculptures
http://www.premier-holidays.com/info/18_exquisite_cinematic_sand_sculptures.aspx

and more sand sculptures
https://www.google.com/search?q=sand+sculptures

CrazyNeutrino said:

Sand sculptures…

Yeah, there’s some big competition that used to be held at the end of my street (recently moved 45km up the peninsula to Frankston). The sand they ‘sculpt’ is probably closer in nature to sandstone or clay than the stuff you’ll find at the beach – The sculptures survive rain, wind, hail, and kids. You could probably walk all over most of the those sculptures without damaging them.

Now the evidence is irrefutable.

Time is indeed fading.

http://villafanestudios.com/gallery/the-sand-2

Not a castle: