Cracks are actually required for reinforced concrete to work properly. The concretes got to give so the steal can take the tension, and you want big cracks to s

Cracks are actually required for reinforced concrete to work properly. The concretes got to give so the steal can take the tension, and you want big cracks to show up during before and during failure, specifically because it's a warning sign. But it's highly dependant on size and location.