Optimizing Screening for Recycled Asphalt Pavement
By Serge Raymond, MAJOR Product Specialist
Millions of tons of recycled asphalt pavement (RAP) is used in asphalt mixtures each year, and the popularity of the product is only increasing. It makes sense. Virgin aggregate isn’t cheap, and there’s a ready supply of RAP just waiting to be used.
After it’s milled from the road, taking advantage of RAP requires special processing before it can be incorporated into asphalt mix. An important step in RAP utilization is screening to the correct spec. However, the nature of the material can present challenges such as inefficiency, blinding and stuck-together material. High performance screen media can combat those issues by improving stratification, solving screening problems and reducing downtime.
Here are three key benefits of high performance FLEX-MAT screen media for screening RAP.
Greater Efficiency
Like most aggregates processes, RAP must be sent through a crusher before it can be screened. Crushing isn’t cheap, so it pays to optimize the screening process to ensure all right-size pieces make it through the screen rather than being returned to the crusher.
FLEX-MAT high vibration wire screens improve screening efficiency and cut crushing costs. MAJOR bonds the high vibration wires with polyurethane strips instead of weaving them. This allows the wires to vibrate independently under material contact, better spreading the material over the decks and improving overall stratification.
Reduce Blinding
One reason for the high value placed on RAP is because it retains much of the oil required to bond asphalt, reducing the need to add binders to create a final product. However, that beneficial feature for the final mix — combined with the fact that RAP stockpiles often absorb large amounts of moisture — translates to an abrasive and sticky product for screening. The tricky agglomeration of RAP fines leads to blinding of screen media openings. This is particularly true in warm weather.
Because of its high vibration qualities, FLEX-MAT is ideal for virtually eliminating blinding issues in most applications. The independent movement of the wires dislodges blinding material, optimizing open area for better screening.
Dislodge Stuck Material
Similar to the blinding problems, the sticky nature of RAP often results in material that has been crushed to size, yet sticks together. On traditional screen media this might cause pegging or improper stratification, allowing already-sized material to get kicked back to the crusher. FLEX-MAT solves this problem. The high vibration of the wires, combined with the vibration of the screen box itself, breaks apart the stuck material to be sized and sent on to the next step in the process.
Contact your local MAJOR dealer today to learn how you can start saving money screening recycled asphalt pavement with FLEX-MAT. Visit www.majorflexmat.com to learn more.