Asphalt Mixing Plants. & Asphalt Recycling. Asphalt Mixing Plants. Batch Plants Batch Plant Tour. Batch Plant Operation. Batch plant.

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1 Asphalt Mixing Plants Asphalt Mixing Plants & Asphalt Recycling AAPA training Types of mixing plants Batch plants Drum mixing plants Raw materials handling Mixing processes Plant recycling of asphalt Asphalt surge and storage Process control Batch Plants Batch Plant Tour What are they Advantages Disadvantages Aggregate Batch Plant Operation electromagnetic vibratory chute variable speed continuous belt Drying & heating oil or gas burners revolving inclined drum with lifting flights Screening unit Batch plant aggregate elevated and screened into hot bins 1

2 Batch Plant Operation Batch Plant Weigh batching aggregate discharged to weigh hopper bitumen discharged to weigh hopper Chimney Bag filter Mixing cycle aggregate and filler discharged to pugmill dry mix cycle bitumen discharged to pugmill wet mix cycle Storage and delivery separate hot bins direct to trucks Control cabin Aggregate bins and feeders Elevator Dryer Bitumen tanks Screen Hot aggregate bins Weigh hoppers Mixer Reclaimed dust Imported filler Storage sil os Materials Storage Cold Feed Bin Common Facilities Aggregate Cold feed bins Stock piles Filler Elevated silos Binder Separate heated storage tanks for each class (170, 320, 600, modified etc) Storage temps 150 o 125 o C Aggregate Dryers 2

3 Access Door Segmented Sprocket Elevator Platform Screens Handrails Work Platform Elevator Buckets Chain Chain High Bin Indicators Hot Bins Bin Extension Module Low Bin Indicators Inclined Walkway Bin Top Section Hot Elevator The Batch Tower Discharge Gates Work Platform Agg. Weigh Hopper Bit. Weigh Bucket Pugmill Reject & Overflow Chutes Work Platform Pugmill Discharge Gates Tower Legs Bin Bottom Section Mixer Section Pugmill Drive Elevator Buckets Entry Chute Segmented Sprocket Access Door 3

4 Pugmill Plant Control Systems LOAD CELLS FLOAT SWITCH LIQUID BITUMEN BITUMEN SPRAY BAR DRIVE PUGMILL GATE CYLINDER PADDLE TIPS MIXING SHAFTS NI-HARD LINERS REDUCER SHANKS Drum Mix Plant What are they Advantages Disadvantages Drum Plant Operation Aggregate feed - variable rate belt (weigh belt system under cold bin - oil or gas burners - revolving inclined drum - injection of bitumen - injection of recycled material - mixing process - bitumen protection Storage and delivery - surge bin - storage bin Drum Mix Plant Recycle materials Bag filter Chimney Weigher Aggregate bins and feeders Mixing drum Bitumen tanks Burner M eter Pump Storage sil os Fi ller silo Drum mix plant 4

5 Parallel flow drum mixer Counter-flow Drum Mixer Counterflow Drum Mixer Mobile Counterflow Drum Mixer Drying zone Heating zone Mixing zone Exhaust outlet Reclaimed feed Aggregate feed Aggregate Extended burner Bitumen Filler Dryer discharge Drum mixer discharge 5

6 Drum Plant Tour Double Barrel Drum Mixer Tandem Drum Mixer Tandem Drum Mixer Bag house for dust collection Exhaust outlet Silo for filler additive Aggregate feed Dryer drum Rotary Dryer Burner Reclaimed feed Elevator for virgin aggregates Virgin aggregate storage and feed system Aggregate Dryer discharge Mixer drum Bitumen Filler Mixer discharge Rotary Mixer Bitumen storage Recycled materials storage Recycled materials elevator and feed system (direct to mixer) Asphalt Surge and Storage Bins < Advantages continuous steady plant operation balance fluctuations in demand faster truck loading can be stored for delivery outside normal hours < Operation Storage time depends on configuration and mix type Must be designed and operated correctly to minimise or avoid segregation 6

7 Asphalt Surge Bins Recycling of Asphalt < Batch Plants < Modified drum mixing plants Split feed of materials Counterflow mixer Drum within a drum (double drum) Tandem drum Indirect heating Microwave Asphalt Recycling System (MARS) Portable RAP produc on plant with stockpiles 7

8 Advantages of RAP SRA maximum RAP% Sustainability Reduced use of natural resources (binders and aggregates) Reduced dependence of landfill Pavement strengthening Increases the binder stiffness for high RAP % Warm Mix Asphalt extra advantages in reduced impact on binder for very high RAP % Note: the new QLD specification will allow the same as NSW Process Control Testing of raw materials cold aggregate feed filler bitumen Control, monitoring and testing of production Cold aggregate feeders and weighing devices Drying Screening Batching and mixing Testing of manufactured product Statistical Process Control References Austroads Guide to Pavement Technology Part 4B: Asphalt AAPA IG-3, Asphalt Plant Process Control AAPA/Austroads Work Tip 15, Asphalt Production Process Control 8