‘If you look after the pennies, the dollars will look after themselves’

Brian Morrow, P.E., Esq.

|  February 22, 2013 |

Pennies DO matter!


PennyBut it’s not about cutting corners to save money. It’s about using doing your homework and understanding calculations in mix design.  He points out that when designing a mix, it’s important ton conduct a quick review of mix volumetrics to make sure you know what you think you know.


This makes it important, he says, for a person to go back to beginning and not just use the information on which he or she has been trained by another person or through internal training.

“You can really get into trouble by not understanding  volumetrics,” Buchanan explains. “You need to understand impact of aggregate grading on volumetrics, of asphalt grading on volumetrics. Most critical volumetric property is VMA. VMA is one of those targets that is sometimes very difficult to achieve. How achieve it? That is the million dollar question. The whole question dovetails into other concepts.”




“Never be too proud to review the basics,” he says. “Pride has cost a lot companies a lot of money. These days that’s the last thing you can afford. Very likely it is costing you a lot of money.”


Typically, during production, you will lose VMA, Buchanan says.” If you are designing with a VMA of 14.5, typically you are going to 1/2 to 7/10 of VMA during production.  This is referred to as “VMA collapse” and is due to excess volume.



Typically, coarse aggregates make it easier to get the correct gravity, Buchanan says. With fine aggregate, you can have issue of getting the correct GSP determined. That is the cause of the test method.”

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.


“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.”


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.”



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.”