Alternative Materials

Plastic is the bane of environmentalists: it's non-biodegradable (lasts forever, basically), harmful to wildlife, and it's made with petroleum - 3 strikes!

The sad-happiest gif ever? 
Here are some funnier animals trapped in plastic to cheer you up
(spoiler alert: they're all cats) 

Unfortunately, plastic is far from "out" - it's just too darn useful to restrict. So we'll have to improve its biodegradability - and Harvard has taken a good step in that direction. They've made plastic materials out of shrimp shells! Alternative construction techniques will be key in building a sustainable future, because recycling doesn't always work:

And only 7% of plastic is recycled at all

Scientists have also figured out a new way to make concrete that repels water and actually flexes a bit. "Hydrophobic" (literally meaning "scared of water") concrete could prevent water from seeping into the road, where it can freeze and expand to crack the pavement. The expansion of water when it freezes is a very odd characteristic; most materials get smaller when they freeze and expand when they are melted, but water freezing forms a crystalline structure that makes ice slightly bigger than the water that made it up - which is also why it floats!

Animation vs. Real life

It's also important that concrete is a bit elastic (which means it can bend and still return to its original shape) so that it can take some punishment without cracking or breaking, requiring expensive repairs.

We'll talk about this particular concrete bridge tomorrow - it's literally my favorite thing to teach