For approximately 30 years, Vacuum Tower Asphalt Extenders (VTAEs) have been blended as part of asphalt binders and, until recently, no adverse effects on pavement performance have been reported. Also known as Re-fined Vacuum Tower Bottoms (RVTBs), Re-fined Engine Oil Bottoms (REOB), Waste Engine Oil Residue (WEOR), and asphalt flux, the asphalt additive has recently come under fire. Some research has suggested that binders have been mixed with 15% to 30% VTAE, while the industry standard is generally to incorporate less than 10% of VTAE. Conflicting research has led to confusion and misinformation about the use of this additive in HMA mixes and the performance in the field. “In the last six months, the use of VTAE has become a very hot topic and there is a lot of poor information circulating in the industry,” says Gerald Huber, Associate Director of Research for Heritage Research Group in Indianapolis. “There’s an impression that used motor oil is being poured into mixes, and that it’s a waste product, which isn’t accurate. Some researchers are • Burner supply • burner installation • burner combustion service • • burner control systems • hot oil heater service • • PLC control systems for complete plant automation • spare parts • • valve trains • T.S.S.A. Approvals • • Combustion Efficiency Test for Optimum Fuel Utilization • • Safety Audits • 24/7 Service • "WE'RE IN BUSINESS WITH OUR CUSTOMERS" Head Office: (905) 547-5757 • Toll Free: 1-877-235-8387 • Fax: (905) 549-1848 www.blackhawkcombustion.com 589 Cannon Street East, Hamilton, ON L8L 2G6 12 OHMPA | ASPHALTOPICS *Jim Walton - President and General Manager jim@blackhawkcombustion.com Doug Whitelaw – Manager, Asphalt Division Doug@blackhawkcombustion.com www .blackh awkcombusti on. com conducting tests and saying that it performs fine; while others are doing non-standard tests and saying that the additive creates problems. A lot of rumours are flying around, with many people not really knowing that VTAE is.” VTAE is what remains from the distillation of used motor oil. The used oil is recycled at refineries, where it undergoes a multiple-stage distillation process to return the material to a base oil. VTAE, a co-product of the refining process, is a thick hydrocarbon substance with properties that have been shown to improve the performance of asphalt binder. VTAE contains iron and other metals from a vehicle’s engine. The material also contains phosphorous and zinc from viscosity enhancers and anti-friction polymers, which are present in the engine oil. Elevated levels of zinc in an asphalt binder, which do not occur naturally in crude oil, is used as one of the markers to reveal that VTAE is present. In response to conflicting research results on VTAE, Heritage Research Group conducted a study for the Illinois Department of Transportation last spring and presented a paper on the research at CTAA in November. The study compared the properties of a Superpave binder grade of PG 58-28 that was formulated with nine per cent of VTAE, as well as another PG 58-28 formulated without VTAE. A thorough set of binder testing, including Superpave PG Binder Testing, X-Ray Fluorescence, Polycyclic Aromatic Compound (PAC) content, gel permeation chromatography (GPC) and thermogravimetric analysis (TGA) was performed to compare the effects of blending VTAE on binder grading, chemical composition, environmental impact, and compatibility of VTAE with asphalt binder. A second portion of the study, comparing the mixture performance of HMA both with neat PG 58-28 and PG 58-28 containing VTAE, provided volumetric analysis and examined resistance to moisture damage, resistance to rutting, mixture stiffness and fatigue resistance. The mixtures also underwent an environmental assessment using leachate testing. The results of the study show that asphalt binders, with and without VTAE, age at a similar rate and ››
“Our study indicated that there isn’t any rapid hardening in the asphalt binder or mix with VTAE and ... no cancer causing materials.” – Gerald Huber “The key thing we need is a national forum to show data and make recommendations to the standard setting agencies.” – Gerald Huber FALL <strong>2014</strong> 13
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