Greenville Goes Green: An Article Written for Roads & Bridges Magazine in April 2011 by Blair Barnhardt, APM
Over forty years ago, a small businessperson in America ran out of hot mixed asphalt on a paving project he had to finish before winter. With no hot mixed asphalt available to his forces, and a pending driving blizzard, this young man rallied his troops to bear torches, hand rakes and used motor oil to heat up the old asphalt in place and rejuvenate it on site. That following spring, there was no discernable difference in appearance with the new asphalt and the recycled asphalt on the project so this small businessperson went on to build his first hot in place asphalt recycling train. Moreover, this same person was one of the three founding fathers of our Asphalt Recycling and Reclaiming Association (ARRA), the voice of our recycling industry in North America, and the world. (ARRA and Federal Highways Administration (FHWA) wrote the Basic Asphalt Recycling Manual (BARM), the textbook that we use in our National Highway Institute Training Workshops)
Two score of years has passed and this person’s son has built the premiere set of machines to perform what he has coined the Re-HEAT® 100% hot in place asphalt recycling process. Unlike its predecessors in the industry this equipment does not employ the three well-known ARRA sub disciplines that we teach in classroom (scarify, remix or repave) rather we refer to this as a newly formed hybrid process. The Re-HEAT® equipment train heats the insitu asphalt roadway up to 600 Deg. F, picks up the hot asphalt from the road base, rejuvenates it in an on board mixing drum and redistributes it at 300 Deg. F consistent temperature via a conventional paving screed. Once conventional compaction equipment compacts the 2 to 3 inch thick layer of fresh recycled Re-HEAT® asphalt, the traffic can begin to use it immediately.
By definition, the Re-HEAT® process is an on-site, in place, pavement rehabilitation method that consists of heating the existing pavement with a thermal transfer of up to 600 degrees F, removing the aged and distressed surface course asphalt, adding a polymer modified asphalt-rejuvenating emulsion, mixing the material uniformly in an on-board mixing drum, re-laying the recycled material, followed by conventional compaction equipment. Unlike some of the other in-place recycling trains that are well suited to long stretches of county and state roads, the Re-HEAT® units occupy a mere 200 linear feet and can articulate when required to get in and around city cul de sacs and traffic circles. Moreover, the Re-HEAT® train is capable of literally peeling off an asphalt overlay from an underlying concrete pavement, tack the concrete, and re apply the rejuvenated hot mixed asphalt to the agencies street.
In the case of Greenville, MS, their City Engineer headed up a pavement evaluation and selected the most appropriate streets for the Re-HEAT® process. Mr. Anderson states, “While the work is ongoing at the time of this article, and weather has caused some delays, some of the streets that have been rehabilitated to date are Robertshaw from Hwy 1 to Colorado, Trailwood from Reed Road to Anne Stokes St. Also, at typical cross section of the road is 24′ wide, 3″ of asphalt and 8″ of crushed stone”.
Unlike other methods of in-place, recycling such as heater scarified hot in place, cold in place recycling and full depth reclamation, the Re-HEAT® method does not require a final wearing course such as microsurfacing or hot mixed asphalt paving. While all of the recycling techniques just mentioned will always save 30% to 40% in comparison to conventional rehabilitation techniques, the Re-HEAT® may offer the greatest savings of all to the agency provided the in-situ road section is an appropriate match for the process. (The author would like to stress the importance of a comprehensive pavement distress evaluation married to the most appropriate recycling and pavement preservation strategy at the correct time to achieve the maximum savings and service life).
While I get frustrated at times having spent the latter 15 years teaching asphalt recycling and pavement preservation across the country and seeing low to moderate interest for processes that could potentially save their agencies 30-50% of their annual budget for roads, I am inspired by the latest developments in this equipment and how one agency had taken full advantage.
Much like the story of the young businessperson above who persevered to build his small business innovations into eco-efficient asphalt recycling machines for the world to embrace, The City of Greenville has grown into a prosperous place perched on the highest part of the Mighty Mississippi between Vicksburg and Memphis. Located in the heart of the Mississippi Delta, Greenville is a town of spirit that has survived flood, fever and fire. In many ways the City has not changed. It is the same City led by the spirit of men who built it, those weary men who, returning from the Civil War, found their homes in ashes and rebuilt it.
The city of 130 years now is face to face with another rebuilding of sorts, not unlike that of its ancestors. The largest port on the Mississippi River, Greenville has a plethora of aging infrastructure and 150 miles of roads that require rehabilitation. I sat down last week and had a candid conversation with Mayor Heather McTeer Hudson and her City Engineer Mr. Lorenzo Anderson, PE. The Mayor and her staff make an exemplary case study of how any city or county in America can save millions by implementing a solid pavement management, recycling and preservation program. Our United States Department of Transportation (FHWA) has long since proven that this type of three legged stool approach can save agencies millions by using green recycling techniques coupled with life extending pavement preservation techniques.
Several years back, Mayor Hudson challenged her department heads to come up with methods of rehabilitation for their infrastructure that would not only save money but also be more energy efficient and sustainable. “Going green and the economy are synonymous, Lorenzo brought great ideas to the table including job creation, costs savings and benefits for the community”, says Hudson. The Mayor also gave the City Engineer the go ahead to purchase MicroPAVER™ pavement management software during this period and her staff went out, gathered pavement distress survey data, and began to load it into the computer software. Their average network level pavement condition index (PCI with 0 being impassable and 100 being new or having major rehabilitation) was in the high 50s.
“Once we settled on the Re-HEAT® method as the most suitable means of in-place rehabilitation for our streets we started the bid process. As we were the first agency in Mississippi to implement this hybrid type of hot-in-place recycling work, we called agencies such as the Florida Department of Transportation (DOT) and Ohio DOT to obtain historical information on their experiences with this process and guidance. Since we do have a local paving contractor in the City, we also allowed for the option of a two inch mill and inlay bid in lieu of the Re-HEAT® process at the time of the letting”, states City Engineer Lorenzo Anderson.
“Based on the competitive bids that we received, we were pleasantly surprised to see that with the Re-HEAT® process we could plan to do 43 city streets instead of the original 20 that we had budgeted with the conventional mill and inlay process used in previous years. With the 50% savings we are getting we can do over twice as many roads”, proclaims Mayor Hudson. “This is great for our people, businesses and growth in our City! Now I can say that green is the new green. When the equipment arrived on the first section of work, and we all went out there to see it, touch it, and watch it in action, we couldn’t believe how fast and efficient Re-HEAT® turned it (the old road) over into a new street without the long line of trucks and noisy, dusty milling equipment”, emphasizes Mayor Hudson.
“In fact the local State wide paving company CEO visited the jobsite and got a vision of how everything was going to go and got a good idea that recycling is the way to go’, says the Mayor. “During a trip to France last year, I saw firsthand how advanced some European agencies are when it comes to asphalt recycling and sustainability. We have a great opportunity with our City to get everyone on board and be at the forefront of it, not necessarily putting someone out of a job, with Re-HEAT® it is good for the community, environment and the future by using our resources most wisely”, reiterates the Mayor.
Recently appointed to Chair the Environmental Protection Agency’s (EPA) Local Government Advisory Committee (LGAC), Mayor Hudson comments “since the Re-HEAT® train emits 65% less emissions than a stand-alone asphalt plant and has 80% less of a carbon footprint because of its eco-efficient design means a lot to me and the colleagues that are part of my committee. This in-place process eliminated the trucking of over thirty thousand tons of millings and asphalt on one job alone. That equates to over 2,000 truckloads of resources that will not be driving over our other streets and damaging them to get to and from the project. Our committee has discussed emissions problems in North Carolina and West Coast states but we feel that if there are problems with pollution in some parts of the country, eventually it will become a problem nationwide”.
Lorenzo Anderson adds, “Our network PCI ratings are increasing about 7 points a year since we implemented the MicroPAVER™ pavement evaluation and management system and combined it with asphalt recycling. While we do some of our worst streets with a reclaimer (full depth reclamation is another discipline with ARRA), our biggest cost savings comes with the Re-HEAT® train. Once the road is hot in place recycled, we reset the PCI in our software to 100, and fully expect to see a 12-15 year life cycle similar to that of a mill and inlay at half the cost.”
It is worth noting that streets typically fall about three PCI points per year when left unattended, so the fact that Greenville streets are going up 7 points a year on average is a huge testament to their overall approach. Mr. Anderson plans to implement other pavement preservation techniques such as micro surfacing and thin overlays in the future once their backlog of poor condition roads are rehabilitated with the Re-HEAT® process.
For the past, few years Lorenzo Anderson has been using asphalt millings to make his gravel roads last longer, full depth reclamation for his roads with PCIs fewer than 50. He also plans to use the Re-HEAT® process once the initial contract is finished. “I especially like the idea that the Re-HEAT® layer offers twice the crack mitigation against the underlying cracks versus a conventional mill and inlay”, states Mr. Anderson.
Combining a solid pavement management program such as MicroPAVER™, asphalt recycling and pavement preservation have certainly helped Mayor Hudson save millions of dollars for her citizens in Greenville. Mayor Hudson touts, “green is the new green!” When I asked the Mayor as member of the Alumnae Association of Atlanta’s Spelman College, what advice you would give to our Atlanta City Mayor Kasim Reed, she said emphatically, “Get recycling asphalt!”
“This is an easy way to make a big difference with our environment; we were the first City in Mississippi to use the Re-HEAT® process to recycle our roads in place without a wearing course. I will be telling anyone who will listen, the LGAC members, county commissioners, city politicians; this is a no brainer for us! This process takes so much less time and we are in and out of neighborhoods quickly. The timesavings is not something that everyone talks about, but community members are well aware of the long delays, limited access to driveways, messy tack coat, dust, lines down and noise from conventional mill and inlay projects. They appreciate what we have done so far, one-day traffic control people, once they pass their house they are finished. The residents leave from an old road in the morning and return to a new road that afternoon”.
Mayor Hudson and City Engineer Anderson would welcome any questions that the reader may have regarding this article. For further information, please contact the author of this article firstname.lastname@example.org. Mr. Barnhardt is a National Highways Institute (NHI) Certified Instructor for Federal Highways Administration (FHWA), Local Technical Assistance Program (LTAP) National Instructor and a course designer and instructor (pavement preservation, recycling and management) for a prominent USA University. His consulting firm also specializes in MicroPAVER™ and StreetSaver® pavement evaluation services.
ReHEAT® HIR Train in Action
Here is the link to the digital version at Roads and Bridges http://www.roadsbridges.com/sites/default/files/60_PE%20Market_0411RB.pdf