“If we discharge a mix at 275 degrees and we’re going to have a 20 degree loss during transit, and another 20 degree loss to put it on the ground and through a material transfer vehicle, I get a 40 degree loss,” he says. “So that puts the maximum compaction temperature at 235 degrees. But that temperature will also diminish rapidly once it has been placed, depending on the thickness of the lift, the wind conditions and the amount of water on your breakdown roller. So you have to look at quite a few variables to decide that.
“That’s why we still run hot mix,” Brown says. “When your temperature diminishes very much, we’ve found that you have to work pretty hard at compaction to achieve good density results.”
Brown says he likes warm mix, and he says owners like it because you don’t oxidize the binder as much.
“You’re not burning off the light ends of the asphalt and hardening it as much as with hot mix. So warm mix should give you longer life in the field. I think our owners like it, and I like it, because I want our product to be long-lasting and meet their expectations.”