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45 posts categorized "Regional and State Issues/Policy"

October 26, 2016

SCDOT & Sloan Rebuild I-85

Sloan I85 recapAdapted from "Fast Fix for Failing Freeway" by Tom Kuennen for Asphalt Contractor

A unique design for warm mix asphalt (WMA) enabled the South Carolina DOT (SCDOT) and its contractor, Sloan Construction, to get a mid-winter start early in 2016 on urgent reconstruction of failing I-85 in the northwestern corner of the Palmetto State. Because WMA can be compacted to required density at lower ambient temperatures, it can lengthen the paving season by enabling winter paving.

The warm mix additive also served as a compaction aid that permitted Sloan to quickly get specified density on twin lifts totaling nine inches, in time-limited night work, to avoid severe penalties for failure to reopen the highway in time for the morning rush in the busy Spartanburg—Greenville corridor.

On this project, in a single one-night shift, as much as nine inches of delaminated, failed pavement would be milled, and the warm mix additive Evotherm® allowed placement of two, four and one-half inch lifts in that single shift, rather than the three, three-inch lifts that would have been required under standard specs, making it impossible to open the pavement by morning rush hour.

The I-85 work was taking place between mile marker 56 to 68, milling out left and center lanes from five to nine inches, and for the right hand lane, milling out 10 inches and putting nine inches back. 

"The DOT realized that, in starting the project last year, the structure of the road didn't hold up the way they wanted it," said Dennis Ayers, senior project manager for Sloan North Region. "They re-let the contract to put in a new base course and reconstruct the road to handle the traffic."

"When we first started we were going to do a two or four inch mill-and-fill," said Chad W. Hawkins, P.E., C.P.M., state materials engineer, SCDOT, Columbia. "But some of the milling process got down into delaminated areas, and that's when the project was put on hold, and we thought 'What do we do now?'".

The pavements in this section were constructed in the 1950s and 60s, so finding out what went wrong is problematic. "Realistically, our two, three and four inch mill-and-fills over the last 50 years have caught up with us," Hawkins said. "It's time to do a major reconstruction, and that's what were finding on a lot of our interstates. We're having to do more than put a four inch 'band-aid'."

On a night in the northbound lanes in July 2016, crews were milling out 10 inches of failed pavement, and were replacing it with two, four and one-half inch lifts of leveling course pavement. They paved 1,000 feet in a single night shift, leaving room for the final driving course.

There, Ingevity's Evotherm enabled Sloan to get density on the first lift, and place the second four and one-half inch lift right on top of the first. Both lifts cooled rapidly to permit timely opening to traffic on the second lift.

Target densities were being met on site and in test strips. Also, Sloan was getting 93 percent density on the cold longitudinal joints, which go down nine inches. "The job is going well," said Todd K. Carroll, P.E., resident construction engineer, SCDOT, Spartanburg County. "They are able to produce a lot of mix every night, very efficiently. We've had a good project so far."

Read the full article in Asphalt Contractor Magazine here.

 

July 18, 2016

Oklahoma Is Where It's At


OKDOT LTPPHow does warm mix asphalt (WMA) perform compared to hot mix asphalt (HMA) in the long term? How is foam different than chemical additives? What happens to an asphalt mix when WMA is used in conjunction with RAP? These and many other questions are on the minds of USDOT, FHWA and State Highway Agency leadership. In order to find answers, the FHWA’s LTPP launched a new Specific Pavement Study (SPS) that will monitor the long-term performance of WMA. The purpose of the SPS-10 experiment, as explained on LTPP’s website, is to “narrow the knowledge gap that currently exists between the performance of WMA and HMA pavements...SPS-10...is designed to explore how a set of primary factors influence pavement performance. These factors include the WMA technology used, environmental elements (temperature and moisture), and traffic loadings.”

Projects are planned across the U.S. The first projects were constructed in 2015, with plans to construct more in 2016. Currently, the SHA tracks the project’s performance for five to six years post construction, with performance data being posted to the FHWA’s LTPP Database.

Each project has three core test sections: a HMA control, WMA with foam, and WMA with a chemical additive. Highway agencies have the opportunity to include supplemental test sections in order to perform additional research that meets their specific needs. The Oklahoma Department of Transportation (ODOT) is a great example of an Agency that is strategically partnering with the FHWA, LTPP and other key players in order to monitor road performance. As part of ODOT’s trial, contractor TJ Campbell chose to use Evotherm® and Evoflex® CA. Ingevity, under the leadership of Richard Steger, P.E., is also assisting ODOT with asphalt binder and mix testing. These results are expected in approximately two months, while LTPP is expected to publish their data by 2017.

We applaud ODOT on their SPS-10 efforts and look forward to the results. Keep up the great work while we wait.

 

June 29, 2016

Trailblazing Clean Air in Casselberry

If the word “trailblazer” is defined as “pioneer or innovator,” then the City of Casselberry, Florida, certainly fits the bill. For several years, Casselberry has had a goal of being a truly “green” city. In this vein, the city developed a city-wide road improvement program that would allow roads to be paved at the lowest possible temperatures in order to minimize their carbon footprint.

 

Casselberry_LaChanceIn early 2013, the City of Casselberry developed its own Specification for Warm Mix Asphalt Pavement (CASB 334), based on the Florida Department of Transportation’s (FDOT) specification, but tailored to better suit projects of the size and nature of the local government. This made the city the first in the state to require the use of WMA instead of HMA for its large public road rehabilitation projects. Kelly Brock, Assistant Public Works Director and City Engineer for the City of Casselberry, explains: “We now have the benefit of saving energy, reducing emissions and improving working conditions, compaction and pavement longevity.”

The city’s first project using this WMA specification in 2013 was Road Rehabilitation Area 1-3,a milling and resurfacing of approximately eight miles. Kelly Brock continues: “Since then, another seven miles of road rehabilitation and reconstruction have been completed with WMA, for a total of 15 miles through April of 2016. It’s a total of more than 20,000 tons of WMA.”

Today, the city has been awarded Honorable Mention for the 2016 Clean Air Award from the Central Florida Clean Air Team. City of Casselberry, blaze on!

November 30, 2015

Mac n Cheese

Mac cheese

Macaroni and cheese appears at every Thanksgiving dinner at my house. NCAT Director Randy West must have had the holidays on his mind when talking about RAP and WMA with Equipment World magazine. "They go together, like peanut butter and jelly or macaroni and cheese," he said referring to the "excellent" rut and crack resistance in high RAP, WMA pavements. Other highlights from the article include:

  • RAP & WMA projects winning NAPA Quality in Construction Awards
  • 40% RAP and WMA for thinlay, residential work in Texas

Evotherm improves compaction and workability for warm mix asphalt mix designs with RAP contents up to 35%. The introduction of Evoflex, alone or in combination with Evotherm, can make even higher binder replacement percentages possible. These new mix designs venture into the 50% territory, achieving high performance at an exceptional value. As good as mac 'n cheese, but I will stick to my mom's recipe this week.

Author: Heather Dolan

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