The Pros and Cons of Concrete

From ancient Rome to modern China, concrete is one of humanity's favorite building materials. Tim Harford looks at concrete's history and how we view it. "Architecturally, concrete implies lazy, soulless structures: ugly office blocks for provincial bureaucrats; multistory parking garages with stairwells that smell of urine. Yet it can also be shaped into forms that many people find beautiful—think of the Sydney Opera House, or Oscar Niemeyer's cathedral in Brasilia."

Concrete is versatile, but it isn't easily repurposed. "That's the fundamental contradiction of concrete: incredibly flexible while you're making something, utterly inflexible once it's made." It's also long-lasting, and will outlive materials like wood and metal.

But that's not necessarily the case for all buildings constructed from concrete. Harford writes, "Reinforced concrete is much stronger and more practical than the unreinforced stuff. It can span larger gaps, allowing concrete to soar in the form of bridges and skyscrapers. But here’s the problem: if cheaply made, it will rot from the inside as water gradually seeps in through tiny cracks in the concrete and rusts the steel."

There are methods to prevent that decay, but it's already causing problems in the U.S., and will soon cause issues in China's "concrete forests" of high-rise housing. Harford suggests that perhaps concrete is best used where it can immediately improve needy people's lives, and gives us several examples.