Mix that stays unstable under compaction, shifting and cracking ahead of the roller drum rather than densifying. Some mixes are tender only in a middle temperature band, the tender zone, often from about 240 F down to 190 F, and roll fine above and below it. Causes include excess fines or sand, rounded aggregate, too much binder, moisture in the mix, or a binder that is soft at that temperature.
It's tender between 240 and 200, so finish breakdown early, park the rollers, then come back when it firms up.
Also heard as
- tender
Related terms
Checking
Short, closely spaced hairline cracks across the mat that open up under the rollers during compaction.
Shoving
Localized bulging and sliding of the asphalt surface where traffic brakes, turns or accelerates.
Breakdown roller
The first roller behind the paver, which does most of the compaction while the mat is still hot.
Fines
The dust-sized part of the aggregate passing the No. 200 sieve, which stiffens the binder into a mastic.