Magic sand is a blend of play sand, water and cornstarch. It does not harden permanently and is used as a modeling clay for children.
To make sand harden, first you need water. Without water, sand is very soft, and soft sand is horrible for making sand castles or any sand sculptures. But if you pour water on sand, then leave it alone for a few hours, it should harden all by itself. But even though the sand is hardened, it is not unbreakeable, so be careful.
It is impossible to cook moon sand to harden it because, as the commercial says, moon sand never dries out.
you can melt sand in very high temperatures, mix it with certain minerals, then it will harden into glass.
the kind of sand that is used in sand sculptures is reguler sand just with a touch of water so it may harden just like if you have dry sand then you cant do anything when it is wet you may sculpt.
Limestone
Sort of, you can use the finer sand. Though some won't work because it isn't fine enough for the ball to harden.
Mortar has fine rock called, "Sand" in it. There is also finely pulverized limestone in it that helps harden it.
Concrete is composed of water, cement and sand. It has three constituents. Concrete is mixed as a wet mixture, poured into place and allowed to harden and dry.
The present tense of "harden" is "harden." For example, "The clay hardens as it dries."
The binder in concrete is usually cement. Cement causes the aggregate and sand to bind together mechanically and harden to make a solid surface.
Yes, harden is a verb.