The Preventative Maintenance Thin Lift Surface overlay is described as an HMA overlay of approximately how thick?

• A. 0.50 inches
• B. 0.60 inches
• C. 0.75 inches
• D. 1.25 inches

Answer: (C)

The main idea here is how thick a Preventative Maintenance Thin Lift Surface overlay is meant to be. This PM thin lift is a very light wearing surface intended to seal the pavement and restore ride quality without doing a full structural layer. The recommended thickness is about three-quarters of an inch. That amount provides enough material to cover minor surface distresses, improve smoothness and skid resistance, and seal against moisture, while keeping the job economical and suitable for a quick, single-pass application with standard paving equipment. If it were thinner, such as half an inch, it wouldn’t reliably address some surface imperfections or provide a durable wearing surface. If it were much thicker, around an inch or more, it would start behaving more like a heavier, structural overlay, which isn’t the goal of preventive maintenance and would increase costs and construction time.