Stuff Matters: Exploring the Marvelous Materials That Shape Our Man-Made World

by Mark Miodownik

As a kid I was so obsessed with stories of famous scientists who solved fundamental problems on the back of envelopes that I used to bring old envelopes with me to school and practice solving problems on the back of them.

“How long will the concrete take to dry, do you think?” a man with a dog asked me, while we were both peering through the viewing window of the hoardings. “I dunno,” I lied. My lie was intended to cut the conversation short, which it did. It was a habitual lie, born of living in London and finding ways of politely avoiding talking to strangers. Especially as I didn’t know how he, or his dog, would take to my beginning our acquaintance by correcting him: concrete doesn’t dry out. Quite the opposite, water is an ingredient of concrete.

you want to make your own concrete you need some calcium carbonate, which is the main constituent of limestone, a rock formed from the compressed layers of living organisms over millions of years and then fused together by the heat and pressure of the movement of the Earth’s crust.

Gels are semisolid and wobbly types of matter—the jelly served at children’s parties is a gel, and so too is a lot of toothpaste. It doesn’t slosh around like a liquid because it has an internal skeleton that prevents the liquid moving.

Tracking down the origin of such human errors can be tricky since, from the exterior, the concrete looks fine. The supervising engineer of the building of JFK Airport noticed through routine tests that the concrete arriving on trucks before noon had good strength when it set, but that arriving just after noon was substantially weaker. Puzzled, he investigated all possible reasons for this but was unable to find the answer until he resorted to following the truck delivering the concrete on its journey to the airport. He found that around noon the driver was in the habit of taking a break for lunch and would hose the concrete with water before doing so in the belief that adding extra water would keep the concrete liquid for longer.

material that is not just strong but also fire-, storm-, and waterproof, and, crucially, cheap enough for everyone in the world to afford it. Reinforced concrete is that material. At £100 per ton, concrete is by a long way the cheapest building material in the world.

the upkeep of concrete structures represents a huge and growing effort. To make matters more difficult, many of these structures are in environments that we don’t want to have to revisit on a regular basis, such as the Øresund Bridge connecting Sweden and Denmark, or the inner core of a nuclear power station. In these situations it would be ideal to find a way to allow concrete to look after itself, to engineer concrete to be self-healing. Such a concrete does now exist, and although it is in its infancy it has already been shown to work.

Self-healing concrete has these bacteria embedded inside it along with a form of starch, which acts as food for the bacteria.

It’s the sort of idea that might sound good in theory but never work in practice. But it does work. Research now shows that cracked concrete that has been prepared in this way can recover 90 percent of its strength thanks to these bacteria. This self-healing concrete is now being developed for use in real engineering structures.

perhaps its biggest application may be in disaster zones, where tents made in situ from rolls of concrete dropped from the air can create a temporary city in a matter of days, one that will keep out the rain, wind, and sun for years while rebuilding efforts continue.

without the Maillard reaction the world would be a much less delicious place: it is the Maillard reaction that is responsible for the flavor of bread crust, roasted vegetables, and many other roasted, savory flavors. In this case, the Maillard reaction is responsible for the nutty, meaty flavors of chocolate,

Its extreme thinness, transparency, strength, and electronic properties mean also that it may end up being the material of choice for touch interfaces of the future, not just the touch screens we are used to but perhaps bringing touch sensitivity to whole objects and even buildings.

Paper cups may seem sustainable because paper is recyclable, but the wax coating required to make them waterproof makes this almost impossible. For real sustainability, we must look to ceramics.

We are all sensitive to the meanings of materials, whether consciously or subconsciously. And since everything is made from something, these meanings pervade our minds. We are being bombarded with them constantly by our environment. Whether we are on a farm or in a city, on a train or a plane, in a library or a shopping mall, they affect us. Of course, designers and architects consciously use these meanings to create clothes, products, and buildings that we like, that we identify with, that we want to surround ourselves with. In this way the meanings of materials are reinforced by our collective behavior and so take on a collective meaning.