For the asphalt industry, the New Year will signal a long, hard look into the role RAP and RAS will play for various state agencies. For the first time in almost two decades, the future of reclaimed asphalt use is somewhat unclear.
Brought about by myriad questions relative to basic material characterization, consistency and performance, reclaimed asphalt products are now being studied with a much deeper field of view. Long gone are the days of maximizing RAP and RAS with relative impunity. Instead, some agencies are now placing moratoriums on the use of RAS, while limiting the volume of virgin binder that can be replaced with RAP.
These changes are raising a series of questions that may not be answered for some time, including:
- How will this affect mix economics?
- Could these changes impact the availability of virgin materials?
- And, perhaps most relevant to the ultimate decision makers, how will this ultimately affect performance?
Despite the uncertainty, one constant will inevitably emerge over time — necessity breeds innovation. Let’s explore this axiom:
Rejuvenators have been around for decades and the fundamental science behind how rejuvenators work has been well understood for about as long. The term ‘rejuvenators’ is often used encompass a wider class of additives that imparts some effect on asphalt mixes containing aged binders. However, a deeper look into basic asphalt chemistry suggests that most rejuvenators are not created equally.
In short, a majority of rejuvenators actually are nothing of the sort. This sub-class of additives provides the mix with basic viscosity reduction, allowing for easier handling and improved plant operation. However, it has little impact on the short or long-term performance of the mix.
A more representative term to describe true rejuvenators is ‘regenerators’ since they offer a much broader range of benefits. By restoring an appropriate balance of chemical constituents to the aged binder (these constituents are either lost or chemically altered during aging and environmental exposure), regenerators have the capability of supplying mixes with short-term workability, improved handling at the plant and enhanced long-term performance on par with that of traditional, virgin mixes.
So, what does this have to do with agencies largely moving away from the free run use of reclaimed binders? For starters, it’s important that this industry recognizes the importance of the continued use of RAP and RAS. It’s critical from an economic standpoint as well as from an optics perspective; and, this is where regenerators are positioned to have a significant impact.
Blacklidge currently has a commercially available solution that could prove to be a great asset to the utilization of higher quantities of reclaimed materials, without sacrificing performance. As previously mentioned, a majority of the additives that are available to the market offer little more than some short-term benefit to mixes containing reclaimed binders. Products like Blacklidge’s ReGen® are proven to offer a greater range of benefits and have even demonstrated acceptable performance when used in blends produced with up to 100 percent RAP.
Armed with this knowledge and assurance, agencies could ultimately allow for the use of RAP and RAS at far greater levels, provided they are blended with the right type of additive. Using reclaimed binders in asphalt mixes is prudent, strategic, economically viable, responsible and — with products like ReGen — has the ability to be used without compromising durability. I look forward to digging deeper into the subject of regenerators in RAP and RAS in 2020.