Engineering
Why Concrete Cracks and How Reinforcement Controls It
Quick fact
Even unreinforced concrete cracks under tension at just about one-tenth of its compressive strength, which is why steel bars are placed in the tension zones to take over and keep the cracks tightly closed.
Why this is interesting
Ever wondered why concrete sidewalks and bridges develop cracks even when they look solid? The surprising truth is that concrete is designed to crack—but reinforcement makes the cracks harmless.