‘If you look after the pennies, the dollars will look after themselves’
The test method is such that materials with a lot of fines, such as -200, can give a misleading result. This can cause you to undershoot your bulk gravity and have bulk gravity and absorption that is too high.
Relating that back to VMA, a critical factor in VMA is bulk gravity of aggregate blend.
“The takeaway is that if you are getting incorrect bulk gravity — if the gravity too low — the result will be a slightly lower VMA calculated and you are directly penalizing yourself,” Buchanan says. “A 100th change in your bulk gravity is a 3/10 change in your VMA.”
With regard to aggregate gravities, if you are calculating gravities, Buchanan says, “you should pay very close attention to aggregate absorption. If at all possible, use the absolute lowest absorption as possible. The higher the absorption, the more liquid asphalt will be absorbed in the stone so you are just wasting money. A good rule of thumb is that asphalt absorption will be about 50 percent of water absorption.”
Buchanan gave me an example from his own company. He says this Oldcastle realizes that liquid asphalt price drives the mix cost so anything you can do optimize your mix with regard to the amount of virgin liquid in the mix is going to go directly to your ability to make money.
“You assume that your virgin liquid is about $550 per ton,” he says. That means every 1/10 of liquid you can save has an impact of 55 cents per mix ton. That is a lot money.”
Oldcastle did 44 million tons, plus, Buchanan told me. If you take the factoid we just discussed, that is a potential savings of $23 million.
“In an industry that is driven by volume, this is essential ,” Buchanan says. “Just saving s few cents per ton makes a difference! The savings incrementally are small. Once you hit the volume escalator, it is a tremendous savings. Pennies Matter! You can’t fall victim to thinking pennies don’t matter.”
Buchanan finishes our conversation with a quote from Paul Getty: “’If you look after the pennies, the dollars will look after themselves.’ That is the philosophy every [operation should take.”
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