Tips for Success with RAP

• Consider recycling as an option during design stages of all rehabilitation projects.
• Evaluate RAP and report its composition in plans, specifications and estimates to successfully use greater percentages of RAP in HMA mixtures.
• Perform enough pavement sampling to estimate variability of material properties.
• Decrease the handling and hauling of RAP to maximize its value.
• Separate and identify by source large quantities of RAP obtained from different sources.
• Produce a homogenous RAP product from a “composite” pile by first blending it thoroughly with a front-end loader or bulldozer. Then crush the largest RAP stone size to one smaller than the top-size in the hot mix being produced (e.g., 0.625 in. for a 0.75 in. top-size mix). This ensures the asphalt bond is broken as much as possible and eliminates oversized stones.
• Fractionate RAP material into two or more stockpiles, dividing the RAP into coarse and fine fractions using either a 3/8-inch screen or a ½-inch screen.
• Avoid low, horizontal RAP piles, which have a tendency to hold water. Large cone- shaped stockpiles, originally thought to cause re-agglomeration, are now thought to be better. Experience has proven that RAP tends to form a crust over the exterior that is eight to 10 inches thick.
• Avoid driving front-end loaders and bulldozers directly on RAP stockpiles to minimize compaction.
  Cover RAP stockpiles when feasible because RAP doesn’t shed water or drain like other aggregates. However, tarps should not be used because they cause condensation.
• Place RAP on a solid paved surface to improve drainage and reduce soil contamination during loading.

For more information

RAP Stockpile Management and Processing in Texas: State of the Practice and Proposed Guidelines, Texas A&M University, Texas Transportation Institute, 2009, 6092-1