Nominal maximum aggregate size, defined as one sieve size larger than the first sieve that retains more than 10 percent of the aggregate. It names the mix (9.5, 12.5, 19, 25 or 37.5 mm) and sets both the VMA minimum and the thinnest lift the mix can be placed in. Surface courses are usually 9.5 or 12.5 mm for smoothness and texture, while lower lifts use 19 or 25 mm for strength and economy.
Plan calls for an inch and a half of 19 mm mix, that's way too thin for the NMAS, ask the engineer about going to a 9.5.
Also heard as
- nominal maximum aggregate size
- nominal max
Related terms
Gradation
The distribution of particle sizes in an aggregate blend, reported as percent passing each sieve.
Lift
One layer of mix placed and compacted in a single pass of the paver.
VMA
Voids in mineral aggregate: the space between aggregate particles available for binder and air.
Superpave
The performance-based system for grading binders and designing asphalt mixes around climate and traffic.