ReLIXER™ is the leading RAP rejuvenator in the marketplace. This Frequently Asked Questions (FAQ) document will answer many common questions on binder and asphalt rejuvenation and why ReLIXER leads the industry as the most impactful, best-performing additive solution.
Asphalt rejuvenation involves restoring the balance of properties within the aged binder of Reclaimed Asphalt Pavement (RAP), and making the RAP binder contribute meaningfully to the total liquids in the mix.
ReLIXER works equally well with Dense Graded and Gap Graded mixes. Provided the mix design is appropriate, success with all types is achievable. In RAP mixes, a key issue is ensuring that the particle size gradation (RAP + aggregate) is within the prescribed specifications. To this end, it is always helpful to classify the RAP into Coarse / Medium / Fine grades. By doing so, increased amounts of RAP can be included in the Mix Design. It is also very helpful to homogenize RAP piles prior to use.
A good rejuvenator must bring about several benefits (attributes) to the mix. Even though one common measure of rejuvenation is softening of the binder, this is only one facet. A well-designed rejuvenator will do all of these:
It must be capable of penetrating the RAP particle quickly and work within the time-frames of normal mix production and silo storage (diffusivity).
It must restore the balance of properties to the aged binder, restoring functionality and performance.
It must provide stiffness reduction to high RAP mixes, ensuring easy laydown and compaction.
It must help the mix meet performance specifications.
It must do all of the above and contribute to the long-term durability of the roadway.
Several types of rejuvenators have been tried in the marketplace. These include:
Hydrocarbon oils. These work by softening the base binder and were popular earlier when lower levels of RAP were used. However, these oils may suffer from multiple drawbacks. These are a non-green chemistry, many are hazardous chemicals, and they may lack rejuvenation and dosage efficiency (particularly for high RAP mixes). They might also be prone to accelerated aging.
REOBS (Engine Oil Bottoms). Whether refined, or unrefined, these may suffer from some of the same drawbacks as mentioned with hydrocarbon oils. While the refined versions are better than the unrefined ones, many US and Canadian states have banned their use following claims of roadway failures.
Softer Binders. In the past, particularly at lower RAP percentages in mixes, softer binders were employed. These may only be effective up to a point, as they certainly cannot be used in the case of 100% RAP mixes. Additionally, depending on how the softening has been achieved, these may also be vulnerable to poor aging
Bio-Oil Blends. These are emerging as the top choice in a wide variety of settings. Benefits include:
Easy to use and do not require heated storage.
Compatible with a wide variety of binders.
Dosage efficiency – they can be engineered to provide a good balance of properties in the mix and confer adequate aging resistance.
Based on sustainable, green, and non-hazardous chemistry.
ReLIXER is a product of years of development and has been deployed in roadways across several continents since 2014. Professor Hussain Bahia (University of Wisconsin) pioneered many of the test techniques used to determine the “genes” of good rejuvenation, and has been instrumental in the development and deployment of ReLIXER. The Modified Asphalt Research Center (MARC) and Prof. Bahia are long-standing collaborators with Sripath. They continue to serve as a valuable technical resource, along with other leading academics around the world, to customers of Sripath.
Our customer service is as comprehensive as our rejuvenation solutions. We understand the unique challenges of each project and product. Bringing years of experience working with customers, researchers, and regulatory authorities across the globe, our team helps develop the right formulation including dosage charts, blending options, as well as lab tests and field trials. Frequently, our staff is on the job site during the first production and laydown. Our technical support team not only manages logistics and delivery, but is ongoing for customers as they always have access to the latest testing, data and research through our world-wide network of affiliates.
While rejuvenator manufacturers have abided by the traditional performance guidelines of roadway authorities, it is important to recognize that these historically formulaic approaches are not always applicable to high RAP mixes.
Some Departments of Transportation, which do not have a long history with high RAP mixes, are becoming increasingly aware of, and adopting different approaches to mixes designed with RAP. For example, specifying that the binder shall be of a certain viscosity, or Pen/SP or PG Grade, does not work. Instead, using a “Balanced Mix” design for high RAP mixes is taking precedence. With a balanced mix design, the goal is to balance contrasting properties and optimize them for roadway performance.
Take rutting and fracture testing (i.e. resistance to cracking failure and fatigue). If a mix is too stiff, the rutting resistance is excellent but the crack resistance is poor. If the mix is too soft, then cracking failure is prevented at the expense of early onset rutting. Aging tests, as well as moisture susceptibility (hot-wet strength tests), are other properties that are key to roadway performance and should be checked before use. Sripath has extensive data and performance testing results for all of these properties on mixes that have been dosed with ReLIXER and utilize high RAP content.
ReLIXER has been used in conjunction with several common additives – Warm Mix Additive (WMA), Anti-Strip, Polymers, Fibers etc. Some other rejuvenators have faced challenges in certain binders. Of course, mix producers have to check against specific standards and requirements in their jurisdiction, and test with their binders.
Typically, selection and dosage is based on the binder in the RAP – binder content, binder age, and desired final properties. ReLIXER enjoys wide-ranging compatibility with most binders. Most customers typically create Blending Charts with ReLIXER based on RAP content and use these charts to adjust dosage based on the specific mix they are producing that given day.
These may include: Grade Modification & Aging Characteristics in Virgin & Extracted Binder, Rutting, Fracture/Fatigue tests, Loose Mix Aging tests, Moisture Damage tests, etc. Not all jurisdictions use all these tests, typically it is based on local circumstances and experience.
ReLIXER enjoys some natural advantages here, which may not be claimed by many others. ReLIXER is free-flowing and easy to use under most ambient conditions, and does not require heating to dispense. It is a safe, bio-oil blend chemistry, with no known associated health hazards. It has a very low odor. It can be deployed in bulk, or in totes/drums, with no special handling or storage issues, and can be added in batch or continuous operations.
ReLIXER is dosage-efficient, and can be used in RAP mixes ranging from 25 – 100%. It has been used in both Base Course and Wear Layer Course. Possessing a high flash point, it can be safely used in the production and laydown of mixes. When mixed with the base binder, it can be used in emulsions for Slurry Coat Seals, Polymer Modified emulsions, and Rejuvenating emulsions.
For incorporation into a mix, ReLIXER can be applied in a variety of ways:
Add to the virgin binder tank
Co-inject with the binder at the drum
Add to the batch mixer either with the binder, or sprayed separately
Spray directly on to the RAP (for 100 % RAP mixes)
This is another key advantage for ReLIXER. Some oils may face restrictions and challenges based on hazardous labeling and effects (as noted on their MSDS sheets). ReLIXER is a non-hazardous, safe, green chemistry that faces no health, safety and environmental restrictions. It also does not require any special labeling for transport and storage, has a high flash point, and does not require any special Personal Protective Equipment (PPE) for handling.
This is based on reporting requirements for individual jurisdictions. Typically, most mix producers do routine Q/C tests on the mix and/or binder, which are provided to the regulatory authorities. In addition, Sripath frequently monitors, and occasionally tests, mix properties of their customers, world-wide, and provides input for dosage or other adjustments.
The easiest method is to note tank/tote levels of ReLIXER and correlate it with production tonnage. Alternatively, most customers do mix testing on production batches to ensure compliance with properties of interest to them.
The published shelf-life of ReLIXER, under normal storage conditions, is one year. Storage stability of material kept in hot bins, or in hot binder tanks, is dictated by the properties of the materials themselves, not by the ReLIXER component.
This depends on the requirements of the regulating authorities. Typically, lab testing, either on the binder (Delta Tc, PAV aging etc) or on the mix (loose mix aging followed by prescribed testing) is used to determine this.
This is commonly asked with regards to cold patch mixes. This is more a function of the formula, rather than of ReLIXER. The role of ReLIXER is only to rejuvenate and activate the binder in the RAP. The stability and usability of the resultant mix is determined by the method of manufacture (hot mix vs. cold mix), ingredients (e.g. Anti-Strip, binder content, etc.), and the storage and ambient conditions of the mix.
We hope that this list provided insight into the world of asphalt rejuvenation. Were there questions that you wish were listed? Let us know by clicking here! Interested in learning more about ReLIXER? Feel free to visit our infographic page as well as the product information page we provide on our site.