From the brains behind brains on, this is the moment of um. Moment of Um. from APM Studios. I'm Squajellum Trunk, Wizard in Training.

Okay, this time it's going to work.

Presto!

Ugh, toadstools, not again.

Ugh, it takes a lot of studying and hard work to become a wizard.

This year I'm supposed to be learning transmutation spells.

That's when you turn one thing into another thing, like turning a leaf into a playing card, or a

handkerchief into a hamster, or a desk into a donkey. I've been trying for weeks to get this spoon to turn into a fork and all I've

managed is a lopsided spatula. But I'm going to keep trying. I mean there are tons of things that can turn into

other things in nature like caterpillars that turn into butterflies or acorns

that grow into oak trees or even gloopy wet concrete that turns into tall hard walls.

I don't actually know how that last one works. I'll have to look through my spellbooks.

I really want to figure this out because Camden wants to know too. My name is Camden I'm from New Mexico.

My question is how does concrete get hardened?

So cement and concrete are two different things.

I am Matthew Adams. I'm an assistant professor at New Jersey Institute of Technology.

Cement is the fine gray powder that we mix into concrete.

Sometimes people will refer to cement paste, which is a mix of cement and water, as just cement as well.

But for something to become concrete, it needs to be the mix of cement, water, sand, rocks, and actually some

air as well.

Those are the five main components that you need for something to got be concrete.

So concrete has, is sort of like a cookie,

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