ASPHALTopics | Fall 2015 | VOL 28 | NO 3

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The VTAE Process asphalt industry,” Palmer says. “Crude refiners don’t always produce soft asphalts which are needed in cold climates or when using high levels of recycled materials, so VTAE and other cutters need to be added to produce the specific grade. VTAE is not a waste product; we produce it purposefully to meet the needs of asphalt blenders.” Crude oil refineries will put HVGO and other distilled materials back into the asphalt so that it cuts the original asphalt to a particular grade. The process uses materials that have already been refined out of the crude and adds another step to the refining process, which makes the asphalt more costly. By contrast, asphalt blended with VTAE can be more economical than conventionally produced binders. The recycling of used motor oil has enormous environmental benefits as well, which according to <strong>NO</strong>RA (National Oil Recyclers Association) amounts to over a billion gallons of collected used motor oil in the U.S. every year. 50 stability machines. Call, write, fax or email your testing equipment requirements. We can calibrate and repair everything we sell! “VTAE is typically indexed to the price of asphalt, so as the price of asphalt rises and falls so does the price of VTAE,” Palmer says. “One of the complaints of transportation agencies is that they are not seeing any savings by using VTAE, but asphalt producers are indeed passing on those savings by virtue of the fact that they are operating in a low bid environment. There is also the perception that inexpensive materials are implicitly inferior, and that they will increase the maintenance costs of a pavement. But there is always a possibility that there is a better product available, which also happens to be less expensive.” The confusion surrounding VTAE can also be attributed to non-standard testing, with some studies concluding that premature cracking in pavements is the direct result of using binders that contain 15 to 30 per cent of VTAE, which is well beyond the recommendation of using less than 10 per cent. The presence of certain dissolved metals in a binder, including zinc (from chemical additive packages added to the original oil), is an indication that VTAE is most likely present. However, it is difficult to measure how much of the dissolved metal content is coming from VTAE alone. Elevated levels of metals do not necessarily indicate that 24 OHMPA | ASPHALTOPICS
a pavement contains a higher percentage of VTAE, and poor performance can be the result of many other factors. “For years, asphalt plants have used recycled motor oil, or RFO, for their burners,” Palmer says. “Studies have shown that the dissolved metals in the burner fuel are captured in the HMA plant baghouse and then returned to the mix, as opposed to being evacuated in the plant’s air emissions system. When those pavements are recycled as RAP, these metals start to accumulate, particularly if the plant again uses recycled oil as its burner fuel. There are trace metals “VTAE is not a waste product; we produce it purposefully to meet the needs of asphalt blenders.”–Al Palmer in other materials, including RAP, aggregates and virgin asphalt which also end up in the mix. Thus, it can be seen that determining the VTAE content of a new binder from binder that is extracted from a pavement core is difficult based on a metals analysis alone.” When used properly and in an appropriate amount, VTAE reduces viscosity and improves the cold temperature properties of binders. The extender helps to reduce the cracking potential of pavement and improves resistance to aging. Engineered softer binders are necessary for HMA mixes that contain RAP and RAS and, as the use of these recycled materials increases, so too will be the need to design softer base asphalt. “We recommend that binders contain from two to eight per cent VTAE, depending on the properties of the base asphalt,” Palmer says. “Once you get past ten per cent of VTAE, then the quality of your base asphalt may be questionable, unless it is being used in conjunction with RAP or RAS. The asphalt portion that comes out of shingles, for example, is very hard. You would have to add more VTAE to compensate for the stiff recycled asphalt. In this case, the concentration of VTAE in the virgin asphalt may need to be greater so that the overall blend of asphalt in the mix meets specifications. Research indicates that if you blend 90 per cent or more of reasonably graded asphalt and 10 per cent or less VTAE, there should not be enough VTAE to affect the blend and make it susceptible to stresses. Again, this is dependent on the properties of the base asphalt used. As with any asphalt blend, it is important to do the necessary lab work to determine if performance characteristics of the mix are acceptable.” ›› FALL <strong>2015</strong> 25
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ASPHALTopics | Fall 2015 | VOL 28 | NO 3

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