But regardless of the types of rollers used, or the order in which they are used, the key to compaction success after the mix has been placed, is to roll the mat while it is still hot. Scherocman says “Get ‘em while they’re hot!” should be the rallying cry of every paving crew because as the mix cools, the binder stiffens and begins to resist further densification.
He says rollers should follow closely behind the paver, and that a good rule of thumb is to complete the breakdown phase before the surface temperature of the mix falls below 250°F. (Scherocman recommends an infrared gun to help track surface temperature of the mix.)
Compaction must be completed while the mix is hot and workable - generally at temperatures above 175°F. The cooler the air temperature and ground (base) temperature, the less time is available for successful compaction and the more difficult it can be to obtain the required density. This is the main reason there’s little asphalt paving during the cold weather.
“The most important thing you can do as a contractor, if you want to give your customer a durable, long-lasting pavement, is to compact it properly,” Scherocman says.