SUB FEATURE
RAP
SAVES THE ENVIRONMENT AND MONEY
Use of recycled asphalt pavement makes sense
By Jeff Winke
It makes total economic and environmental sense to use recycled asphalt pavement ( RAP ) in an asphalt mix design . According to the Federal Highway Administration , there are approximately 2.8 million miles of paved roadways in the U . S . which meant that approximately 18 billion tons of asphalt were used to pave them . And since nearly all asphalt pavement material that is removed from existing roads can be recycled this provides a huge opportunity .
The management of RAP is important because it holds many resources with high value such as oil and sometimes scarce aggregate .
Cold milling is an integral part of the construction cycle of many roads . Asphalt milling removes an old and worn wearing course . It can also be used to improve the surface friction or remove ruts on a wearing course that is otherwise in good condition . Those asphalt millings can become recycled material that can be put back into future roads .
Best practices for milling should always be considered in order to produce a consistent , quality product . The speed of the milling machine can make or break both the quantity and the quality of the material milled . In order to achieve a quality milled material , start and stop slowly . Starting too fast will make a dip . When starting , move forward at a slow pace so the rear tracks can walk into the cut which allows the hydraulics for all legs to adjust accordingly . When stopping , slow down before coming to a complete stop . Also , be sure to maintain a consistent speed when milling . Milling at high speeds puts unneeded wear on the machine and will create a coarse pattern . This can result in larger RAP material , which means the material may have to be run through a crusher before it is useable .
Newer milling machines will have different drum speeds , which , of course , is different than machine speed . Running a milling machine at the highest drum speed at a lower machine speed will help achieve a fine quality texture . This also can make for better sizing of RAP material .
It is also recommended to mill surface
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