In it for the long haul

May 31, 2016

St Johns County

In November of 2015, Saint John County, near Jacksonville, FL, found itself in this dilemma: a 2,000 daily mix ton project, 50 miles from the asphalt plant, with no access to a shuttle buggy. The County wanted a reliable solution to pave an eastbound stretch of East Saint Johns Avenue and found the answer with WMA.

Experienced with warm mix, contractor Atlantic Coast Asphalt (ACA) used a PG 58-22 terminally blended mix with 0.5% Evotherm M1 and 40% rap blend. “Although we had used warm mix in the past,” explains Mike Camilleri, Plant Manager at ACA, “we were concerned with using it in our Marshall design mix and achieving improved and more consistent density compared to HMA. But we discovered many performance benefits by using warm mix on this job.”

The first trucks were loaded at approximately seven o’clock in the morning. Production temperatures began at 330 and were reduced in stages down to 270. The 50-minute haul and lack of a shuttle buggy yielded varying temperature readings behind the screed (between 235-285). Gauge readings on site indicated density values that ranged from 93-94%, which were confirmed with sample cores later in the day.

Press Tompkins, County Engineer at Saint Johns County, reports that the project was an overall success: “A 60℉ production temperature drop in mid-November, along with a 50-minute haul without a shuttle buggy wouldn’t have been possible without Evotherm. And when you factor in the consistent densities, that’s even more of a plus.”

It looks like the initiative and innovation by Saint John County and ACA paid off in the long haul!