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Grimes Asphalt and Paving Goes Green

Posted on: August 23, 2012

The Terex plant at the Grimes plant location has seen modifications over the past two years and none are as impressive and effective as the method for adding Recycled Asphalt to the mix. A design of bins, conveyors, crushers, and screens make up the system that allows the use of recycled asphalt (RAP) in the Hot Mix Asphalt.

The bin that starts the process was originally built to feed recycled shingles in the mix, but with so much RAPin stock, it made sense to utilize the RAP rather than buy shingles. The tear-out is crushed, or screens millings from street projects, and the RAP is loaded into the bin. A screen on top of the bin sorts out material too large to feed through the bottom of the bin onto the conveyor belt.

The larger material sorted out is re-crushed later. The material then travels on a flat conveyor from the bin to another conveyor belt that transports the raw RAP to a small crusher, the RAP Wrangler, which breaks up larger pieces of material that made it through the initial screen. The RAP then goes up a third conveyor to a Scalper. The Scalper has a one inch screen that is tilted at a 45 degree angle and shakes. The shaking motion rattles any material larger than an inch in size downhill and the larger material falls off the edge and piles up under the Scalper. Foreign matter that may be in the tear out like wood or Geo-Fabric also rattles off the Scalper and is discarder. The waste is minimal, maybe a half a Skidloader bucket per 1000 ton.

Once through the Scalper, the RAP makes it final accent up a 50-foot conveyor and falls into the RAP chute. The RAP chute connects to the mixing drum behind the burner. The RAP is mixed in with the hot aggregate and Binder. The finished mix is rolled into the Slat Conveyor and transported up to the Silos where the Hot Mix Asphalt is stored and dispatched into trucks. The trucks are loaded, weighed on the scale, and a load ticket is printed. The Hot Mix Asphalt is then off to a job.

Last season Grimes incorporated nearly 22% of recycled Asphalt into the mix they produced.

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