1. Drum Plants Construction1 HMA Production Senior/Graduate HMA Course

2. Drum Plants Construction2 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 Plants Construction3 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

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5. Drum Plants Construction5 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.

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7. Drum Plants Construction7 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

8. Drum Plants Construction8 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

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10. Drum Plants Construction10 Cold Feed Gradation Control Many styles of feeder controls found in field. All can perform satisfactory proportioning.

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12. Drum Plants Construction12 Asphalt Binder Proportioning Asphalt binder must proportion to aggregate flow. First step in asphalt binder proportioning is measuring aggregate flow. Belt scale is used.

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14. Drum Plants Construction14 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

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17. Drum Plants Construction17 Asphalt Binder Proportioning Asphalt binder must proportion to aggregate flow. Second step is regulating asphalt binder flow. Asphalt binder pumping / metering unit is used.

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20. Drum Plants Construction20 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

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22. Drum Plants Construction22 Plant Automation Many types of systems and levels of complexity found in the field.

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24. Drum Plants Construction24 QUESTIONS ?