Question 7. Why does concrete flake/spall?

Concrete’s volume will change slightly after it has cured. Typically concrete shrinks about 1/16 of an inch over 10 feet. Contractors put joints, wither sawcuts or expansion strips in concrete to encourage the concrete to crack in a more uniform, straight line at the joint when the concrete shrinks and changes its volume. Hence why we call them Control Joints.  They are employed to help control where the concrete will inevitably crack.