Concrete is often used as an auxiliary support around steel bars

And it’s not just big breaks that count:tiny cracks can be just as dangerous.Concrete is often used as a secondary support around steel reinforcements.In this concrete, even small cracks can channel water, oxygen,and carbon dioxide that corrode the steel and lead to disastrous collapse. On structures like bridges and highways that are constantly in use, detecting these problems before they lead to catastrophe becomes a huge and costly challenge.