When Louisiana began to allow asphalt producers to blend polymers in-line, Diamond B Construction quickly jumped on board.
“Essentially when we add the polymer and your PG64 becomes better than a PG70,” he said. “Instead of buying PG70 straight from a supplier, we create our own.”
To truly benefit from this new opportunity, Diamond B purchased an Accu-Shear blending system for one of its plants. Within a few months, Diamond B had an Accu-Shear at all five of its plants.
Diamond B also began to see many benefits from its Accu-Shear systems due to its ability to dynamically foam mixes.
Depending on the application, Louisiana may require up to 4 grades of asphalt binder at a time. In-line blending helps lesson the burden of ordering and storing all of those different grades at once.
The Story Behind Diamond B
Diamond B Construction has five plants across the state of Louisiana, in Monroe, Alexandria, Leesville, New Iberia and Amite, all of which are Astec double barrel drum plants of various sizes.
The company employs around 350 employees, with around five at each plant and 14 on each of its five laydown crews. About 80 percent of the hot mix Diamond B makes is laid by its own crews, which focus primarily on work for Louisiana DOT.
“In some of our more rural markets, if you want to sell the mix you’re going to have to lay it yourself,” Bossier said.
Diamond B also has its’ own milling operations, base operations, bridge operations and other road construction support crews.
Diamond B has lab personnel at every plant, but it also has a lab that does mix design for the entire company at its Amite plant. That’s also where Diamond B mines the gravel it uses. Everything else it uses is limestone coming into the state by rail or water.
The company actually got its start through mining more than 60 years ago, when L.H. Bossier, Bossier’s grandfather, who was mining gravel in Amite, decided to get into asphalt production.
“He sold a lot of gravel to asphalt producers, but he got tired of doing that and figured he’d do it himself,” Bossier said.
Grade Bumping with the Accu-Shear
At each of its five plants, Diamond B has an Accu-Shear for blending and foaming, which helps them bring down their mix temperatures by 20 to 25 degrees.
Louisiana’s minimum temperature is 275 degrees, which Bossier said is right on the highest level of what would be considered warm mix nationally. Diamond B’s mixes still run well above that 275 limit.
When the state began to allow producers to blend polymer additives, Diamond B starting moving down that road.
“We tried the Accu-Shear at one location and we liked the performance,” Bossier said. Although it requires Diamond B to do a little more during the production, testing and mix design stages, Bossier said it’s worth the extra effort.
During mix design and testing, the in-line blending of polymers adds a few steps and variables, Bossier said, compared to buying polymer modified liquid AC straight from the refiner.
This includes shipping liquid AC samples to its polymer supplier and then receiving the blended sample back, running DSR tests in-house on the blended sample along with a third party doing the same for reference, and then running the appropriate controls for blending with the Accu-Shear and additive tanks at the plant.
In most instances, Diamond B is using a PG67 liquid AC and blends it with latex through the Accu-Shear to add polymers and enhance the binder to a higher grade.
Prior to installing its Accu-Shear devices, Diamond B tried several different types of blending equipment, but the company prefers the Accu-Shear process.
“Stansteel works differently than other products because the blending mechanism shears the additive into the liquid, which we find very efficient,” Bossier said.
If You Can’t Blend It, Foam It
Today, Diamond B foams all of its mixes.
“Even if we’re not blending, we’re foaming,” Bossier said, adding that even just the foaming process helps the company’s laydown crews get better compaction.
Bossier said that his crews can tell a difference when rolling foamed mixes.
“The compaction ends up being easier to obtain if you foam,” he said. “Foaming will typically take a few passes out of our typical roller pattern.”
“Another reason we [foam everything], is so we don’t add other variables when troubleshooting,” Bossier said. “Changing that variable can affect how people react when a mix behaves differently.”
Another benefit? “When you foam and drop the temperature, the mix seems to hold the heat pretty well in transport,” Bossier said. Generally, Diamond B’s longest hauls are around 80 miles. Although Bossier can’t say for sure if foaming has let his crews travel further with mix, he knows it’s made a difference in how safe he can feel about the temperature on those longer hauls.
“If it would take 90 minutes to get to a job, I definitely feel better when I know the mix is foamed and that heat loss is going to be limited,” Bossier said. “For producers who are allowed to perform at temps below 270 and really make warm mix, foaming must be an even more dramatic benefit.”
When Diamond B’s trucks have to haul further than 80 miles, the company sometimes adds a rejuvenator to its mix to save the temperature and make it easier to handle the mix when it arrives to the job.
Bossier added that foaming has also helped them see the amperage draw on the slat conveyor decrease when running a dynamically foamed mix, allowed them to keep it in the silo longer, and get the material to release and flow better.