Jul 23, 2021
The Weight of Water
BY Sandy Lender
For this issue of AsphaltPro, we’re focusing on the largest portion by weight of the asphalt mix: aggregates. You’ll see there’s the requisite mention of stockpiles in the training department. Let me expand on the stockpile discussion here by reminding readers of the importance of keeping the stockpile as dry as possible.
Anyone in the asphalt industry will tell you water is the enemy. As of press time, water is being considered one of the bad actors in the horror that took place in Miami June 24.
Rain, water for dust-control, water for aggregate washing, and even water added for mix design purposes adds to drying time while subtracting from burner efficiency. While you want to keep dust down with “engineered” water droplets entrapping dust particles, you also want to keep fuel costs down with efficient drying times, temperatures and methods.
It’s a balancing act for more than fuel cost purposes. When your moisture levels fluctuate during production, your mix controls try to compensate by altering your liquid binder content. Read one way to fight that mess with the “Blackstone Measures Moisture” article here.
All this leads to the notion of best stockpile management. You’ve heard some of this before, I’m sure. Pave under the stockpiles. Pave on a slope. Cover the stockpiles—when feasible—to protect them from the weather. Make sure loader operators consistently pull material from a few feet above the water line of the stockpile when feeding the plant. “Consistently” is the operative word there. Consistent moisture levels in the material hitting the drum will allow more consistent results from a consistent temperature, and so on.
Let’s take a closer look at the concept of paving the stockpile area on a slope.
The point is to direct stormwater runoff away from the base of the stockpiles. Make sure you plan this out to direct water where you want it to go. Personally, having a moat filled with piranha circling the perimeter sounds like a fabulous idea for preventing random visitors. But not everyone has the same violent streak I have. You may want to direct stormwater runoff to a man-made pond for migrating waterfowl, which is a better look for climate stewardship overall.
Luckily, we’re in the asphalt paving industry where designing a sloped pavement to direct stormwater runoff is second nature to our project engineers. We know how to do this for best, optimum, safest effect.
Combining your best stockpile management techniques will result in optimum clean air efficiencies and most reasonable costs. It’s the smart way to manage the weight of water.