The average driver can usually see when pavement deterioration becomes problematic—there will be tearing or rutting on the surface of the road or cracking in wheel paths that decreases safety on the roadway. Underneath the surface of the pavement, however, the signs of deterioration existed long before they were visible and experienced by drivers. Delamination between asphalt layers underneath the surface of pavement is often due to layer debonding or stripping, which typically is not visible, especially in
Source: NDT