In my last blog post, I introduced the concept of true rejuvenators (i.e. regenerators) compared to another category of products that are inaccurately referred to as rejuvenators. This time, I’ll explore this concept in greater detail, take a deeper dive into why regenerators are a superior technology and how they should be implemented.
What is a true rejuvenator?
Two distinctly different categories of products are often lumped together under the term rejuvenators. However, a majority of the additives that claim to rejuvenate aged binders offer little more than short-term viscosity reduction. While this improves mix workability, it does nothing to address the notion of modifying the total binder (virgin + reclaimed binder) over the life of an asphalt mix.
This is how regenerators (like Blacklidge’s ReGen®) differentiate themselves as a superior technology. Instead of simply replenishing the light end saturate fraction of asphalt chemistry (often lost quickly after a mix is produced), regenerators provide a near complete rebalancing of the basic constituents of asphalt chemistry. In short, this rebalancing effect reverses or regenerates aged binders to a condition that one would expect of a virgin binder. This isn’t just accomplished over the short-term. Due to the modification effort of the aged, reclaimed binder, regenerators allow for mix performance to be improved to the point where it is at or near that of a virgin blend.
What does this mean for the industry?
As we enter into a new decade, many states are beginning to reconsider the way they view RAP use. Some are even going so far as limiting the amount of RAP that can be used in the wearing course. While some states are pulling back the reins on RAP use, others are actively pursuing ways to view RAP through a slightly different lens.
CalTrans, for example, has finally approved a state-wide RAP/RAS specification. The new spec allows for the use of RAP at higher quantities provided blending charts are used to adjust the total binder to meet a specified grade. Given the market dynamics in California, softer binders are typically very expensive, which offsets any competitive advantage experienced by using mixes with higher RAP quantities. However, if states using blending charts to determine final grade were to consider the use of ReGen, then they would not only meet their specification but also experience improved, long-term performance.
Balanced Mix Designs are another hot button topic on the minds of a lot of state agencies. What the final designation will look like differs from one state to another. However, one aspect appears to be consistent across state lines – implementation of ΔTC. Mixes containing high percentages of reclaimed asphalt coupled with ReGen have demonstrated exceptional results relative to ΔTC by allowing the final grade to be pulled within the limitations imposed by each agency.
It wouldn’t be a complete story if economics weren’t addressed in some capacity. While the asphalt industry can be constrained by the acquisition cost of raw materials, RAP (and even RAS, to some extent) helps offset the cost of liquid binder. Additionally, RAP offers a competitive advantage for producers who have access to large quantities of recycled materials. Utilizing these materials is a prudent venture in an effort to drive down the cost of mix production.
In the end, the adoption of regenerators is a win-win. Using products like ReGen offer producers economic advantages that also improve the short and long-term durability of their mixes. This results in better, more cost-effective, road construction while encouraging robust competition in the marketplace.