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HMA Production

HMA Production. Senior/Graduate HMA Course. What you will learn…. How gradation is controlled in a drum-mixer How asphalt is controlled in a drum-mixer Different styles of drum-mixers Using RAP with a drum plant. Drum-Mix Production. Hot Mix Asphalt production characterized by:

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HMA Production

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  1. HMA Production Senior/Graduate HMA Course

  2. What you will learn…. • How gradation is controlled in a drum-mixer • How asphalt is controlled in a drum-mixer • Different styles of drum-mixers • Using RAP with a drum plant

  3. Drum-Mix Production Hot Mix Asphalt production characterized by: • Gradation Control at Cold Feed • Measure aggregate flow with belt scale • Meter asphalt binder to aggregate flow • Produce HMA continuously

  4. Cold Feed Proportioning Composite gradation is controlled at cold feed by proportioning material from individual bins. Gradation and quality of the individual materials is controlled at the quarry.

  5. Cold Feed Proportioning Variation in material flow from individual bins: • Based on variable speed motor on belt • Adjustable manual gates help control minimum and maximum flow

  6. Cold Feed Proportioning • Accomplished by calibrating the feeders • Material output is charted against belt speed in calibration charts • Different charts are created for different gate settings on the same feeder

  7. Cold Feed Gradation Control Many styles of feeder controls found in field. All can perform satisfactory proportioning.

  8. Asphalt Binder Proportioning Asphalt binder must proportion to aggregate flow. First step in asphalt binder proportioning is measuring aggregate flow. Belt scale is used.

  9. How a Belt Scale Works • Weigh bridge measures weight of aggregate. • Speed sensor measures speed of belt. • “Integrator / Totalizer” calculates aggregate flow in ton (tonnes) per hour • “Integrator / Totalizer” reports flow rate to plant control system

  10. Asphalt Binder Proportioning Asphalt binder must proportion to aggregate flow. Second step is regulating asphalt binder flow. Asphalt binder pumping / metering unit is used.

  11. How the Asphalt Binder Proportioning System Works • Controls system reads wet aggregate flow from belt scale. • Controls accepts moisture content entered by operator to establish dry flow rate of aggregate • Control system accepts target asphalt content entered by operator. • Control system drives pumping/metering unit flow control device. • Control system adjusts asphalt binder flow control system based on signal received back from meter

  12. Plant Automation Many types of systems and levels of complexity found in the field.

  13. QUESTIONS ?

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