The following article excerpts were written by Richard Williammee, Jr., MS, PE as an editorial in the Texas Asphalt Magazine Fall 2012 edition. Titled “Asphalt Release Agents Go National,” the article describes the rise of the asphalt release agent and the various testing that these asphalt products undergo to ensure an effective and environmentally-friendly product was accessible to paving crews for various asphalt jobs.
“Every producer and contractor who works with asphaltic concrete mixes, whether hot, warm, or cold, has experienced the need to clean up equipment on a daily if not more than daily basis. For decades, this has been done with readily available diesel and solvents. These products work because they are relatively cheap, easy to obtain, and clean the equipment really well. However, in performing this task, they are also causing the asphalt to “soften” and strip off the aggregates. Without this “glue,” the mix quality is compromised and people designing, constructing, and maintaining roadway systems have recognized the need to preserve the integrity of the asphaltic concrete mixes while protecting the environment.”
This emphasizes the need for a water-emulsifiable solvent like PavePro or the development of a release agent that isn’t destructive or dangerous: enter, PavePro Blue.
New Tests and Procedures
“Asphalt Release Agent (ARA) is now a general term used for products that have been developed to prevent stripping and replace the environmentally hazardous diesel and solvents. From 1997 to 2004, the Texas Department of Transportation (TxDOT) created a new test procedure and specification for ARAs, created a list of approved products and then required it in their Specifications.”
PavePro Blue is a full-strength asphalt release agent tested and approved by TxDOT’s new program for truck beds and other paving equipment. Its advanced formula is not only the safest solution to preventing asphalt buildup, but it beats out competing products in side-by-side comparisons conducted on various job sites.
The asphalt release agent testing “consists of 3 test procedures; a Stripping test, a Mixture Slide test, and an Asphalt Performance test.
The Stripping Test
The Stripping test involves taking a vendor’s product, filling up a quart jar, and placing actual hot mix into the solution. Based on the liquid discoloration, it is reported as “No Stripping,” “Slight Stripping,” “Moderate Stripping,” or “Severe Stripping.” Additionally, a visual check of the hot mix is performed to see if the asphalt is stripping from the aggregate; this is done for very dark to opaque products.
The Mixture Slide Test
The Mixture Slide Test involves the use of an actual plate cut out of a TxDOT truck bed. The ARA is sprayed onto the plate then Hot Mix is placed on the plate. After a specified time, the plate is tilted to see how much of the mix slides off. This is repeated at least twice more without ARA product reapplication. This test simulates the effect of mix in truck beds.
The Asphalt Performance Test
The Asphalt Performance test involves the application of asphalt liquid poured onto the same truck bed plate. After a certain rest period, the asphalt “patty” is lifted from the plate. This test is repeated a minimum of twice more without reapplication of the ARA product. An accumulative weight is recorded until the specified percentage is achieved. Some ARAs will actually allow more than 3 lifts, which lowers the cost of the product. This test simulates asphalt sitting on items like the pavers, rollers, rakes, lutes, shovels, and elevator slats at the Hot Mix plants.
The “Approved List”
During the years that TxDOT was developing and running products through their own test procedure, a large percentage failed the Stripping and Mixture Slide tests; a requirement to be approved for truck beds. Eventually, a list of acceptable products developed. However, from the products passing these two tests, approximately 90% failed the Asphalt Performance test which TxDOT listed separately in their Approval List for use on all other field equipment; i.e., pavers, rollers, lutes, shovels, and conveyor belts. Testing of products from across the nation has also revealed the same trend.”
PavePro Blue passed ALL parts of the TxDOT testing procedure, earning full approval on the TxDOT-Approved Asphalt Release Agents list using NTPEP data and in accordance with Departmental Materials Specification DMS-6410, “Asphalt Release Agents.”
“TxDOT plans to replace its’ current process with one that uses NTPEP data to determine whether a product will meet its’ specification. As only two products have been released by the Manufacturers for public use, TxDOT has decided to delay its’ conversion date to possibly the end of 2012 and are waiting to see if additional products meet the specifications. Many other States are now looking at their ARA program and Quality Products List. The concept is catching on with the DOTs and Industry to help create and place quality mixes, to provide a long lasting pavement to the traveling public, and protect the environment.”
Interested in learning more about our asphalt release agent, PavePro Blue, or the TxDOT testing procedures? Feel free to reach out to our knowledgeable team and we can answer all of your questions. After all, don’t you want to know your supplier knows a thing or two about the industry? We do.
Richard S. Williammee, Jr., MS, PE, is the TxDOT Fort Worth District Materials Engineer. He received his Bachelor’s Degree in Civil Engineering in 1984 and a Master’s Degree in Geotechnical Engineering in 2010. He has more than 28 years with TxDOT in the Forth Worth District, 10 of those years in Design and Construction and more than 18 years as a Materials Engineer. Richard is also the NTPEP ARA Technical Chairman.