Which surface preparation method reduces structural capacity?

• A. Planing
• B. Milling
• C. PCC Overlay
• D. Cold Milling

Answer: (D)

Removing material from the pavement’s structural section is what changes its ability to carry loads. Cold milling shaves off pavement with a drum, and it can remove beyond just the surface into the underlying base. This reduces the remaining structural capacity until a new layer is placed to restore it. In contrast, planing and asphalt milling mainly take off the top layer while leaving most of the base and subbase intact, so the structural capacity isn’t reduced as much. Adding a PCC overlay actually increases capacity by putting a new concrete layer on top. So the method that reduces structural capacity the most is cold milling.