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Wow, this is huge.

Have you guys ever seen a construction site before, maybe a store, an apartment complex or even a house?

I wonder how the builders decide the size in the shape of the building or what materials to use, where to put the walls?

I think I know somebody who can help us figure this out come on.

Hi, I'm Sophia, and welcome to Alabama's STEM Explorers.

I'm here with my friend Neal at the Hudson Alpha Institute for Biotechnology in Huntsville, Alabama.

I was just talking to him about construction, and I was wondering how do architects come up with buildings?

Like how do they figure out where they need to put the wall and how they need to construct everything?

That's a great question.

You know, an architect, a designer has to think about all the forces that are going to act on a building as they design it.

Let's think about some of the forces, some of the things that would be acting on the structure of a building.

Well, there's gravity, of course.

Yes, as the whole down pushing down that the heavy weights, especially for a multi-story building.

What else if it's really tall, the wind could be really strong That's right.

You have to think about the force of the wind pushing against that building, and it might be coming from different directions.

Anything else you can think of?

Well, depending on your depending on where you live, there might be an earthquake and the ground could be shaking That's right, you would have to think about designing a building that could deal with the movement of an earthquake.

So all of those things deal with issues.

Forces called compression and tension pick up that piece of metal for a second.

And I want you to to squeeze the ends really hard.

Yeah.

So you're putting pressure on this and there's a little bit of a bending here.

You're doing all right.

Yes.

OK.

There's a little bend here in the middle and at the bottom, the metal is compressing.

It's pushing in and at the top of the bend, it's actually pulling apart tension, going ahead and put that down.

Let's do.

Let's show that with something much easier, like a spaghetti noodle.

Oh, there we go.

So there are compression here pushing in and we've got tension pulling apart.

Now, keep on pushing.

Yeah.

Yeah, that was nice.

That was the flying spaghetti.

Spaghetti doesn't work so well with compression or tension.

What about something like a marshmallow?

What about compression?

It's definitely getting a compression.

That's right.

How about tension?

Not too much.

Not so tension.

So your challenge is to think like an architect and to think about compression and tension.

I want you to build a structure, build a building out of nothing but spaghetti and marshmallows.

You can build and tie as high as you want, as short as you want.

You can reinforce it if you want.

And then we're going to put a piece of cardboard on top and we're going to put weights on it, so it needs to have a flat surface.

OK. OK. All right.

Go ahead and get started.

I'm going to step out of the way.

I don't think I've ever seen a house like this before, but I think there's some good shakes around this.

So tell me about the structure that you've chosen.

You've picked some very specific shapes in building this.

Well, one thing that I see a lot in architecture is triangles.

So if you see a bridge, most likely it will be made out of squares.

It'll have reinforcement, a lot of triangles.

And I've seen this because I demonstrate it really quickly.

So let's say I've got a square here and I make one really quickly and I'll make the triangle OK. Let's say we have the forces acting on it.

It'll kind of just bend or it doesn't really hold its shape, but the triangle, it's a little harder for it to bend and it holds its shape very well, so the forces don't affect it as much.

So you've used a lot of triangles, a lot of triangles.

So what we'll do now is we're going to actually clear the table and bring Sophia's structure back in a couple of more.

And test the load to see how well your design would would deal with some pressure and some weight on it.

OK. All right.

Awesome.

We've got three structures here built entirely with spaghetti and marshmallows Now let's see how well they handle load.

Let's start with this one right here.

There are a few triangles in this, but it's mostly wide open squares.

Let's see.

Let's go ahead and put.

All right.

So I think I that's kind of sad, isn't it?

Yeah, OK. Each of these blocks is about ten grams.

So that's about 30 grams of weight.

Not very sturdy at all, and maybe not surprising because there's really no reinforcing.

Yeah, it doesn't have the triangles and reinforcements that this one does.

Exactly.

OK, now let's try yours.

OK. Much stronger so far, and maybe not so surprising.

two stories of blocks.

We might need more.

This one might not go anywhere.

Wow, this is a lot.

Let's stop there for a moment.

You've done a really nice job embracing and reinforcing.

And like you said, the triangles are providing a lot of the they're pushing that low.

They're distributing that load across the base.

That's a much stronger structure than what we did with this one.

I don't know how many more blocks we could put on here, but I think we could go for it for quite a while.

All right.

Now let's look at this structure over here.

Now this structure has a little bit of bracing, but not very much.

It's an open structure.

But this structure was built last week, and so these marshmallows have dried and as they've dried they've become hardened almost like cement.

Mm hmm.

So it'll be interesting to see if even though this structure looks much more like this, if the hardening of the marshmallows actually gives us some additional strength.

So let's see what happens.

Let's see?

Some from here.

Idefinitely more than more weight than this one.

Still holding.

OK, look there.

Oh, yeah.

Yeah, I think we've got a lot that's not going to last very long.

Why don't we put let's put a couple more and see what happens.

That's why I'm here to set the whole thing off.

Well, look at how bent that is, look at how much compression and tension it's experiencing right here.

So holding it, still holding the dried marshmallows are really giving it a lot of strength.

And.

I don't think they're going to go next longer.

Oh, oh my gosh.

So we've talked about the forces that are acting on on a building that an architect has to take into account.

And clearly, this is our stablest structure.

But there's something to be said about the power of of dried marshmallows.

Not that I would surely want to live in a house made of dried marshmallows.

I would probably eat them, eat them instead.

Yes.

So in our next segment, we're going to talk about some of the things that actually provide strength around the frame.

Stay tuned.

We'll talk about concrete in just a minute.

So when I was a kid, my parents built a house, they hired an architect to do this, and it was the first time that I'd seen someone use art skills to do something technical and ultimately to create a building.

So I think from that day, I was hooked in fifth grade.

We used to draw a little floorplan during our quiet time in which we would make little rooms for our Garfield dolls.

So there's a grew up.

I went to Auburn University, I studied the College of Architecture and went on a career path to become an architect .

And I love it every day.

I use computers to do 3D modeling.

I use magic markers.

I use pencils and scales.

Every day, I work with people and collaborate on engineering everything from the structure of the building to how air moves in and out of the building and through the building, how the plumbing engineering works.

We have to specify plumbing fixtures and tiles and materials.

And so there's materials technology that you have to understand to understand how rain is going to move on a building and how a building protect itself from the environment and relate to its landscape and community.

I enjoy being an architect.

I think it is a great combination of art, engineering and people.

Sophia, let's talk about concrete.

That's not something I usually talk about.

No, you're right, but we probably should talk about concrete concrete.

It's so important to our society.

I want you to think about how many times today you've come into contact with concrete.

Probably a lot.

The sidewalks, of course.

Yes, a lot of building materials are concrete.

My house, the foundation is concrete as well.

So it's everywhere.

Did you get here in a car?

Yes.

So you probably were on a road and there's a layer of concrete underneath the asphalt as well.

Really, concrete is a critical building material It's relatively inexpensive.

Why do you think it's also so popular?

Because it's very strong and durable.

It is.

It lasts a long, long time.

So it's an economical building material.

Concrete is a mixture.

You know what a mixture means.

It's a combination of like two or more materials.

That's right.

That's right.

So in this instance, the mixture is of these four things right here.

Water, cement, sand and gravel.

These four things make up concrete.

Now, a lot of people say cement when they're talking about concrete, but cement is only one part of the entire mix.

What is cement?

So cement is actually made from limestone and clay that you dig out of the ground and you mix up and you heat to incredibly high temperatures and then you grind it up into a powder.

And so cement and water together form a paste, and that paste binds the sand and the gravel together and holds it all together.

That's right, it holds it all together.

It's kind of like the glue.

Let's make some concrete.

So over here, you've got all of those components going ahead and put all of those into your container.

There's our gravel.

It can be really small gravel.

It can be big gravel.

Some folks even use iron if they're making incredibly strong concrete.

Yeah, you might.

Yeah, use the spoon to get the sand, the sand out.

The sand also helps bind it, it can be any kind of sand like the sand that you might have on your playground, but you want to make sure you get all the sticks and twigs out of it first.

It's all right.

Don't worry about the mess because you know it's not science if we aren't making a mess.

It's not fun if we aren't making a mess.

Yes, I agree.

See that one came out.

All right.

There's your cement and now the water.

OK, so now blend it all up.

And it might not be easy for you to tell, but concrete is actually the process of making concrete creates a chemical reaction that gives off heat.

So I don't know if you can actually feel it get warm.

It's not very, very warm.

But what happens is a chemical reaction called hydration.

And so this is a model of a molecule of water, one molecule of oxygen and two molecules of hydrogen.

And these are held together by chemical bonds and there's energy in those chemical bonds.

When the water is mixed with the cement, those bonds break, and that breaking of the bonds generates heat.

And then the individual molecules reform with the cement, and they actually create crystals that grow and bind the sand and bind the rocks together.

So over time, the concrete gets hard because of those chemical reactions.

How are you coming over there?

It still looks pretty much.

Yeah, you may need to dig down deep in the into the bottom.

Yeah, it takes work, doesn't it?

Yes.

Some energy into that and you work.

OK, now going ahead, let's pour some of it into this dish.

get some more yeah, get some of the binding material on there, we get.

That's good.

OK, so now it will take several hours for this concrete to begin to harden, which is one reason why concrete is so valuable because while it's still in its liquid form, you can shape it into different materials.

And then over time it hardens.

But it takes weeks for concrete to what's called cure to really build all of those all those crystals as those bonds break.

Let's clear all this away, and let's look at some different mixes of concrete and let's measure their strength.

Sophia, here are some different mixtures of concrete.

This one is all cement.

This one has the mixture.

This is exactly what you just made the cement, the sand, the gravel in the water.

This one actually uses half as much water, and this one uses twice as much sand.

So in this, is it dried and this is it dry?

That's right.

three weeks afterwards, and you can see just from looking at them, they've got different appearances to them.

Like the one that has all the extra sand is a whole lot more gritty.

It's gritty, yes.

And the one that doesn't have anything but cement.

Actually, it's already cracked and it doesn't have any any of the binder because it's just the glue.

So what we're going to do now is we're going to actually put each of these in a clamp and we're going to turn the clamp and see if we can actually crac the concrete.

And how long it takes us to crack the concrete.

But because concrete pieces might fly out when we crack, we're going to go ahead and put on our safety goggles.

Safety first, safety first, always.

All right.

Let's start with this one, which was just cement.

Now, the problem with using just cement is that cement shrinks when it dries, and you can see it's actually already cracked just by itself.

But let's see how long it would take to actually crack it, so go ahead and turn that all the way down.

And once you hit, OK, now let's start from there, let's see how many turns.

And there you go.

You've already put a pretty significant crack in it running the site.

Can you see that?

Yeah.

Yeah.

OK, so this one is not very strong at all.

So let's take it back out.

All right.

Let's try now the mixture that you made the standard concrete mix.

OK. OK, so you said these have been sitting for three weeks.

How long?

Oh, wow.

Yeah.

How long did it take for these to dry?

So these were dry to the touch in just a few hours.

But all of the water that continues to break those bonds apart and form the crystals that can take week and in some cases that actually can take years, concrete can continue to harden years after you've poured it.

Wow.

Yeah.

All right.

So again, we've got to crack.

That was more you put more pressure than you did with just the cement, but we've still got a pretty significant crack.

OK.

This one didn't crack as easily, though, not as easily.

Now let's try our mixture that used half as much water, since it's much harder to work with concrete when you use less water, but it makes a stronger mix.

All right.

So.

I can't do it.

There we go.

All right.

But that took another half turn compared to this one.

But we do now have cracks.

All right.

Let's try our last one, which is where we added twice the amount of sand.

All right.

Give it a shot.

Oh, it's already cracked.

You've already got a crack there.

You got a lot of cracks there.

Yeah, so here I think this one required more pressure than this one did So a different type of Oh my gosh.

Look, though, now that now it's starting to crack here in the plastic as well, let's release that there are material engineers whose job is to test the strength of the concrete that's been poured into building.

So they'll take a sample of the concrete and then once it's cured, they'll actually confirm that it is strong, that it doesn't have any deficits in it.

That's a really important safety job that requires knowing a lot about concrete.

So we've covered a lot of ground from something that is made from four really simple, straightforward experiments.

I have a feeling there are material engineers whose job is to test the strength of the concrete that's been poured into building.. Yeah, definitely something for us to think about So when I was a kid, my grandfather was a self-taught engineer, and he always told us how he worked on the Saturn five rocket, and I thought that looking back, I think that's what instilled in me the idea, the thought to pursue engineering.

And I always was good at math.

And so I just took a leap of faith and stuck with it.

So we're a geotechnical engineering company we do for subsurface explorations and surveys.

We also do a lot of construction material testing soils, concrete reinforcing steel, structural steel and other construction materials.

Concrete is one of the cooler things that we get to see every day.

Uh, it's in every, every job site that I've been out and we'll continue to be from the foundation to slabs to sidewalk to loading docks, retaining walls, uh, concrete masonry units.

Um, it's everywhere.

And it's a major key in construction today.

So these are clearing tanks for concrete.

So we go out in the field and pull samples from concrete trucks when they're doing a poor and we make we test for air and we make a set of cylinders.

Cylinders have to remain on site for at least eight hours to cure out.

And once they do that, we pick them up and bring them here to cure out in a human environment.

Each day is different.

It goes from a rainy day being stuck in the office to a summer day or two or three summer days where I may not be here, I'll be out in the field all the time and go on a different jobs and doing different things.

So I use STEM every day.

The science, technology, math, we basic calculations.

Some are more complex than others when it comes to concrete, the curing out process and the bonding of the cement and aggregate and sand and wate nuclear gauges for technology.

Uh, it it goes it day in and day out.

We use everything that involves around STEM.

I tell middle schoolers that if they had a passion for math or whether they liked solving problems, that engineering would be a good field.

Uh, it's has a plethora of jobs and opportunities out there for you to learn and just grow.

Thanks for watching.

Alabama's STEM Exploreres If you missed anything or you want to watch something again, you can check out our website at Alabama STEM Explorers dot org.

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Thanks again for watching.

We'll be back next week.

Alabama STEM Explorers is made possible by the generous support of Hudson Alpha Institute for Biotechnology, translating the power of genomics into real world results.

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Alabama Math, Science and Technology Initiative, the Alabama Department of Education's initiative to improve math and science teaching statewide.