World of Asphalt Hits St. Louis, Q&A with Kerianne Melillo
By Gavin Jenkins, Senior Managing Editor
The World of Asphalt Show and Conference and AGG1 Academy and Expo starts tomorrow in St. Louis at America’s Center Convention Complex.
Roads & Bridges’ team will be at booth 3135, among the 430 exhibitors in the 230,000 square foot convention center.
There will be 120 education sessions and plenty of opportunity to network at The Community Zone, a new feature to this year’s event.
“Our goal with the Community Zone is to create a relaxed environment where attendees can engage with one another in a dedicated area on the show floor,” said World of Asphalt Show Director, Brittany Schmidtke, in a press release. “It creates a fresh space where thought leaders can share information to a wider audience.”
The show highlights the trends and technology that drive the asphalt industry in North America. Industry trends include recycling, sustainability, innovation, best practices and work force development.
Roads & Bridges’ March issue focused on asphalt, and one feature focused on the topic of recycled asphalt pavement (RAP). Written by Kerianne Melillo, the chief marketing officer for Green Asphalt, the story examined RAP and how a plant in New York is helping to transform the industry.
Leading up to Roads & Bridges’ coverage of World of Asphalt in St. Louis, Melillo answered a few follow-up questions over email.
Save travels to the Gateway City! Stop by our booth if you get a chance!
Could you elaborate on the specific challenges involved in fractionation and how Green Asphalt ensures quality in the absence of virgin aggregates?
We treat our fractionation process as carefully as a quarry treats their aggregate production process. When RAP is accepted at our facility, it is first screened for debris, dirt, or concrete – any dirty loads are turned away. Accepted loads get stockpiled and loaded into an impact crusher. The crushing operation is at the discretion of the lab, who decides when and how quickly the RAP can be crushed due to weather, existing stockpile size, and RAP consistency. These variables are key considerations when fractionating RAP and ultimately lead to the quality of the RAP stockpiles.
On the way up the conveyor belt to the crusher, the RAP passes through a magnet belt that picks out any metal debris as well as a manual picking station where any residual trash, line striping, or debris is removed. Once the RAP is crushed, it is screened through a triple-deck screener and separated into its respective stockpiles.
In order to ensure quality of the RAP, these fractionated RAP stockpiles are handled with strict QA/QC guidelines. Daily moisture content, AC content, and gradations are performed on each stockpile to ensure consistency. Monthly, the stockpiles are sent out for extraction testing with continuous PG grading, which assists the QA/QC manager in determining the proper dosage of rejuvenator for our 100% RAP mixes.
What makes Green Asphalt's patented baghouse system stand out compared to other air filtration systems in the industry?
Green Asphalt’s patented baghouse system has a few key differences to other air filtration systems. Firstly, the baghouse was created to primarily treat blue smoke. When RAP is used to create 100% RAP mixes, all aggregates are covered in AC oil, severely limiting the amount of dust that needs to be treated. The patented bag house works best when there is very little dust loss from a mix, so its filters do not get clogged.
Secondly, the RAP baghouse is a wet system, which is unique in the industry. Water is used to knock the blue smoke out of the exhaust before passing through candle filters that capture the remainder of the contaminants.
Lastly, the patented baghouse is unique as it is a bolt-on option to an existing plant. Rather than requiring a new plant to be set up, the patented baghouse can be attached to an existing plant to create a hybrid plant that can toggle between current, conventional operations and the 100% RAP side. This is a stand-out feature of the patented system, allowing producers to consider 100% RAP with a lower up-front cost and without altering their current operations.
How do the rejuvenating oils used in the production process contribute to the quality and durability of the asphalt?
Rejuvenating oils play a huge role in the creation of 100% RAP. These oils bring the aged RAP back to life and back to a more realistic PG grade. Green Asphalt has experience with lab, plant, and field testing of many different types of rejuvenators. In general, there is a balance between cost and quality. For a producer selling on price, recycled motor or vegetable oil will provide the most cost-effective mix but may only be suitable for driveway or parking lot usage. For a producer meeting a State DOT spec, DOT-approved rejuvenators need to be considered to provide DOT-require performance. Green Asphalt would suggest to anyone looking to increase their RAP to work with rejuvenator companies to find the best product for their needs. Many great products exist, and we believe there is a 100% RAP rejuvenator solution for all mixes.
Are there any unique challenges associated with scaling this technology to other regions with different climates or road requirements?
Asphalt is a geographically sensitive material, varying depending on quality of aggregates, PG grading, required gradations, weather, and road usage. The first step in creating a high-quality, high-RAP mix is to understand your RAP so you can then reverse engineer the RAP to meet the mix you need to create. One your target fractions are identified, based on your mix specifications, understanding the fractionated RAP’s moisture content, AC content, and PG grade will allow you to treat the RAP as needed to create a high-quality product.
Although Green Asphalt has been successful in creating pavement mixes with no virgin aggregates or AC, adding these elements remains an option to be explored in other locations where RAP quality may be more of a challenge. In general, if a producer desires to create 100% RAP mixes, there is always a way to get incredibly close using the RAP they have on hand, regardless of the geography it came from. RB
