Why do roads get potholes?

Let's make a big mess with some dollar-store food items! If you are a school teacher, this science lesson is a pretty easy to replicate in your classroom.

Here's the shopping list:
1 Bottle of Hershey's shell (kind which hardens in the freezer)
1 Sleeve of off-brand graham crackers
1 Small bag of brown sugar
1 Baking pan (or clear glass container)
1 Baking spatula (or piece of cardboard, in my case)
1 Squirt bottle
And for fun, several toy cars, bulldozers, etc.

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Source material:

Did you know a single big-rig truck causes more damage to the street than 1,600 passenger cars? Here's a fun site you can nerd out to!

[keptkozy]

That wasn't his house. He literally just walked into my yard and started doing this. When I asked him to leave, he bit me. Subscribed.

[nathancox]

This was a really intuitive way to explain how potholes form! Also seems like a good excuse for you to buy some new matchbox cars! Haha

[joshualaw]

"Mom, the weird guy in the orange vest is playing with food and toy cars in our garden again!"





All kidding aside, this was a great illustration to describe the weathering and formation of potholes :)

[RavenCarver]

The $1/ month I'm kicking over to you on Patreon is going towards this?

Better step it up to $2/month haha

[Jake-mczk]

Almost didn’t recognise you without sunglasses!

Cool video dude! Awesome as always!

[A.Martin]

Its usually more of a gradual process, once the crack forms then every time a vehicle drives over the crack it forces the water out through the crack with a tiny bit of soil dissolved. and over time more and more soil gets pushed out and a dip develops in the road which when cars hit it they put more force on that spot which accelerates the damage, eventually more cracks form and the asphalt breaks up because it can't handle so much bending from the vehicles driving over it, and a hole has formed.
Preventative maintenance is to find these cracks before the damage happens and seal them up to keep water from getting in. You will often see these black lines on the road where they have sealed cracks. Its not a permanent fix but it will slow down the degrading of that patch of road until it and the rest of the road surface is due for replacement.

[errolv]

Nearly all the pothole explanations here use water. But a pothole making expansion missing is the hydraulic pressure from tires. 1. Water from rain or the gutter gets on the asphalt roadway. 2. Cars roll on the wet asphalt. 3. The weight of the tires pushes the water into any crack. 4. The hydraulic pressure, same as freeze and thaw, opens the crack a bit more. Next car!

[knightcrusader]

Poor Mrs. Maiden China... she got the raw end of the deal here....

[RobShutt]

Most cracking is caused by expansion and contraction of the asphalt due to thermal extremes. Although heavy loads on asphalt not designed for the weight will cause that like you demonstrated. Once the pavement cracks you can prevent a pothole by sealing the crack to keep moisture out. Well done.

[soap]

He’s done it again. Roadside bob has tricked me into learning road knowledge. Love your videos man!

[jandraelune]

There are even more ways in the rust belt to form potholes. Road salt, snowplows, rapid cooling and heating. The salt opens gaps in the ice, this gap concentrates water and sunlight on that point to expedite the process cooling and heating for creating cracks. Snowplows come by instead of leaving the blades just off the pavement, they scrape it and bite into those cracks breaking them wide open.

[MarkReviews]

*SECOND most delicious asphalt I've ever tasted.

[neldjpi]

Best part of this video is his choice to film in a garden and not in a kitchen

[gregr]

Whenever the streets get a new asphalt cover, the very next week I see city workers or utility companies already cutting into it. They ruin the surface right away and when they fill those square holes, it always dips lower than the rest of the street.

[christopherjunkins]

That's not the only way. There's also "Lensing" which is where that water gets under the asphalt and in the winter freezes. As the ice expands, it makes that area wider under the asphalt, then when it melts, it leaves a larger area for more water to come in, freeze, and then expand for more over and over... until *CRACK* the asphalt opens up into that hole or someone drives over it as in your demonstration. It might not be a simi that causes the initial cracking either, just heat values swinging around can cause that as well, it can also be that the asphalt itself just got old and cracked. Either way water finds it's way in and either erodes it as water does, or freezes in the winter pushing up and down on that bit of asphalt making things worse with each iteration until... well, there you go another pot hole.

Then there's also wrecks. Wrecks can cause pot holes as well, if violent enough to cause a car to dig into the road. Also snow-chains left on can do that too... well the opening of the asphalt that is.

[AlexTangBang]

Should we still use asphalt then? Since we need to have trucks transport things. You should do a video on highway road materials! Concrete vs asphalt vs .... dirt? Maybe a quick history on road materials? Stone roads to asphalt to whatever the next material? Great video!

[HavokTheorem]

Glad nobody walked in just as you said "BIG GAPING HOLE IN THE AS-"

[scratchpad]

1:35
Just a few blocks away from me, one of the worst roads along the entire Wasatch Front for this kind of problem is 2700 South in Salt Lake City. I think 3900 South in East Millcreek (which is even closer to me and forms the southern border between Millcreek and Holladay) is a very good contender. I believe it has to do with our many underground springs and a very shallow water table.

[Eschatonx]

Finally! I wonder where you went, glad to see a new video!

[proletariennenaturiste]

When somebody says "explain like you're professor Frink explaining to a five year old."