APE February 2023 | Page 30

“... produce only what you need for a two- to threemonth period since stockpiles of crushed and classified RAP can have a shortened lifespan because the RAP can begin to gather moisture and re-bond to itself ...”
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and intermediate layers separately to help control quality .
Once asphalt millings are removed from the road surface , the contractor needs to find a place to store them until they can be reused .
The transportation , storage and utilization of RAP is always a logistical challenge , but the single most important best practice is to treat RAP the same way you treat virgin materials . This means always keeping the RAP clean and dry before it is reprocessed and put back on the roadways .
According to the National Asphalt Pavement Associations ( NAPA ) “ Best Practices for RAP and RAS Management ,” poor management of RAP stockpiles is commonly cited as a reason agencies are reluctant to increase allowable RAP contents in asphalt mixtures . For production of quality mixes with high RAP contents , excellent material management practices are essential .
When possible , store processed RAP stockpiles under cover , or at least in an area with a
“... produce only what you need for a two- to threemonth period since stockpiles of crushed and classified RAP can have a shortened lifespan because the RAP can begin to gather moisture and re-bond to itself ...”
sloped surface and good drainage . NAPA recommends a paved surface underneath stockpiles to allow for proper drainage .
It is best to use RAP material within two to three months after producing it . Longer storage periods are acceptable when the material is under cover and protected . Also , avoid driving loaders on RAP stockpiles , which can lead to premature compaction of the processed RAP .
A producer should separate the material into two or more stockpiles , based on the size of the RAP particles . A common practice is to separate RAP into a coarse pile , with particles larger ½- or 3 / 8-inch in size , and a fine pile with particles of less than ½-inch or so . That lets contractors use fine RAP in finer asphalt mixtures and the larger-size RAP in coarse mixtures .
The most widely used sizes are ½- to 5 / 8- inch , however some states also allow producers to use smaller than 3 / 4-inch RAP in subbase and binder .
Another best practice is to produce only what you need for a two- to three-month period since stockpiles of crushed and classified RAP can have a shortened lifespan because the RAP can begin to gather moisture and re-bond to itself , which will result in
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