A single layer of pavement laid at one time, described by its compacted thickness. Lift thickness has to suit the aggregate size: a common guideline is at least three times the NMAS for fine-graded mixes and four times for coarse-graded mixes, so the stones can reorient under the rollers. Thicker lifts hold heat longer and compact more easily, while thin lifts on cold days lose heat fast.
Six inches of base goes down in two lifts, three and three, then a two-inch surface lift on top.
Also heard as
- course
- layer
Related terms
NMAS
Nominal maximum aggregate size: the sieve size used to name a mix, such as a 9.5 mm or 19 mm mix.
Mat
The freshly laid strip of asphalt behind the paver, before and during rolling.
Roll-down
The amount a loose mat drops in thickness as the rollers compact it.
Binder course
The intermediate pavement layer placed between the base course and the surface course.