Neither snow nor rain…
Feb 28, 2012
Despite heavy rains during the test section, Wiregrass Construction Company successfully placed their test strip on SR 8 just west of Montgomery, Alabama. After achieving densities above 93% despite the weather, they went on to complete the 50,000 ton job under sunny skies.
The CMI counter flow plant was fired up early to supply private work so when Wiregrass switched over to the Evotherm section the plant was already warmed up. Alabama DOT is proactive when it comes to trying new things so when Wiregrass suggested they allow 40% RAP on the 19mm PG67-22 intermediate coarse the state was on board as long as they used warm mix. Wiregrass Construction has a foamer but decided to use Evotherm because of its benefits with increased RAP at lower temperatures.
A 300T test strip was scheduled for the first day with limited time to get it done because of inclement weather. Paving began at 9:00am with the trucks leaving the plant at 260-265°F consistently. The haul from the plant was roughly 40 minutes. The road was milled from edge of shoulder to center line but paved from center line to edge of road. This 2" intermediate coarse was being used as a leveling coarse. Another 19mm polymer modified intermediate mix is going to be placed over the Evotherm section as a wearing coarse. In the field the mixed arrived at 250°F. The breakdown roller utilized a 7 pass pattern all in vibratory with the intermediate/finish roller utilizing a 5 pass pattern with 2 vibratory and 3 static.
The rain moved in sooner than expected and half way through the test strip the skies opened up. The roller operators shortened the distance between them to compensate for the rapid cooling of the asphalt with little affect on the density. Even with the heavy down pour all cores were very consistent with densities above 93%.
The following day's weather cooperated much better and Wiregrass was scheduled to do 2000-2500T. The plant was fired up at 4:30am and started shipping at 7:00am. By 9:30am there was already 500T placed.
Overall the job went very well and is a huge step forward for Wiregrass and ALDOT with the use of 40% RAP. There is roughly 50,000 tons of total mix on the job with half of that utilizing Evotherm in the intermediate coarse.
Author: Rob Bach