Rejuvenate-and-use-your-RAP-Piles

 

Reclaimed asphalt pavement, or RAP, is surface material that is removed from an existing roadway and then reprocessed for use in future asphalt paving projects. The material is typically milled off of an older or failing road and stored by asphalt plants or central processing facilities. RAP is prized in the asphalt industry as a sustainable and cost-effective way to develop new roadway surfaces without the need to source high amounts of virgin binder and aggregate. When dosed with an effective asphalt rejuvenator, RAP mixes can achieve high-performance outcomes with up to 100% RAP included.  

 

One misconception is that RAP does not need to be treated as a valuable paving material since it would otherwise sit idle on plant sites or in landfills. However, the recycled nature of RAP does not mean that it should be disregarded as less important than other aggregates used in an asphalt mix. In fact, to get the most value in performance and cost savings when using RAP, the material should be treated with the same respect as purchased virgin aggregate and binder.  

 

The quality and consistency of a mix containing RAP depend heavily on how the material is stored and managed. Poor stockpile practices can lead to excess moisture, contamination, and binder variability, making RAP stockpile management practices an essential component of plant operations. Here, we’re sharing five best practices for RAP stockpile management. 

 

  1. Keep RAP Dry and Covered

Moisture is one of the biggest challenges in RAP stockpile management. Excess water can not only increase the energy required for drying during production but can also affect mix design accuracy.  

 

Storing RAP under a tarp, in covered bins, or within a three-sided shelter can drastically reduce moisture absorption. Keeping the material dry can improve plant efficiency, reduce emissions, and allow additives such as asphalt rejuvenators to penetrate more effectively. 

 

Drainage for a RAP stockpile is also important. Even covered piles can absorb ground moisture if they sit on an unpaved or poorly drained surface. Ideally, RAP should be stored on a paved, sloped pad that allows water to drain away from the base.  

 

  1. Control Stockpile Size and Segregation

Large or unorganized RAP stockpiles can make it harder to control consistency in a final mix. RAP material from different sources can contain varying binder grades and aggregate sizes.  

 

Best practice is to segregate RAP, typically by size fraction. Use signs and physical barriers to prevent unintentional mixing. Smaller, well-managed piles also reduce compaction over time and make it easier to re-blend material uniformly before use. 

 

Consistent RAP quality is also critical when incorporating additives. If the material in the stockpile varies widely, predicting how additives such as an asphalt rejuvenator will perform in the final mix becomes difficult. This is due to variability in stiffness, oxidation, or binder properties. Segregating allows producers to develop a mix design with reliable performance across production runs. 

 

  1. Prevent RAP Contamination

While RAP is a recycled material stored outside, producers should strive to prevent contaminants from entering their stockpiles. Examples of contaminants include dirt, vegetation, or other debris that can accumulate over time in unused piles. These impurities can degrade the quality of the final mix if they are not removed.  

 

Preventing contamination is a proactive approach that can help reduce mix property variability. To do this, consider: 

  • Storing RAP on paved or non-dirt surfaces 
  • Locating RAP stockpiles away from active construction or work areas 
  • Loading, turning, and dumping RAP material cleanly 
  • Inspecting RAP piles for foreign material on a regular basis 

  1. Test RAP Regularly

Segregating and homogenizing RAP material for inclusion in a final mix can help reduce variability. However, RAP properties will naturally vary over time depending on when and where they were sourced. RAP stockpiles should be tested periodically when they sit for extended periods, are exposed to extreme weather, or are blended from multiple sources. Seasonal changes can alter moisture content, and prolonged UV exposure may further age the binder.  

 

Plant operators and mix designers should regularly test RAP to determine binder content and properties, aggregate gradation, and moisture levels. Establishing a testing schedule ensures that mix designs stay accurate and that additive selection or dosage can be adjusted proactively. 

 

RAP testing is also important when additives like an asphalt rejuvenator or recycling agent are used. Understanding the stiffness and oxidation level of the aged binder in RAP can help optimize asphalt rejuvenator dosage to meet performance specifications.  

 

  1. Practice Proper Handling

Over time, RAP stockpiles can harden or clump due to compaction, temperature changes, and environmental exposure. This can make the material difficult to blend uniformly during production. Hardened RAP can lead to poor coating of aggregate, inconsistent binder distribution, and issues with mix workability. Clumps of RAP may not heat evenly in the drum or pugmill, resulting in insufficient blending. These inconsistencies can compromise pavement performance for the final mix. 

 

To maintain uniformity and workability, RAP stockpiles should be handled and maintained according to best practices: 

  • Avoid building tall, conical piles that compress material at the base 
  • Use a layered stockpiling method to allow for better air flow and drainage 
  • Periodically turn, blend, or screen the RAP to restore workability and prevent segregation 

 

The Role of Asphalt Rejuvenation in RAP Use 

 

Asphalt producers are under growing pressure to increase sustainability, control costs, and meet evolving performance standards. RAP has become a key component for many looking to solve these challenges. To get the most that RAP can offer and achieve high-performing mixes, the material should be managed and treated as the valuable material that it is. 

 

While RAP is a critical component of sustainable, cost-effective mixes, it can’t do all of the work of achieving performance specifications on its own. Asphalt rejuvenators restore rheological balance to aged binder, which is essential especially when high percentages of RAP are used. Over time, the binder in RAP becomes oxidized and brittle, losing its original flexibility and adhesive properties. Without intervention, this aged binder can lead to cracking, poor workability, and reduced pavement lifespan. Adding an effective rejuvenator like ReLIXER can help mixes achieve targeted performance grades and maintain long-term durability. 

 

For more information about RAP stockpile management, high-RAP mixes, and ReLIXER, , contact info@sripath.com.  

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