Construction of Quality Hot Mix Pavements - 1 Day Course Early Plant PLANTS & PRODUCTION Bob Horan, P.E. Senior Regional Engineer Mechanicsville, Virginia Plants and Production Basic Functions of Plants The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. Store component materials Combine aggregates in proper propor7ons Add and mix liquid binder in proper propor7ons Coat aggregates uniformly Store mixture and load trucks without segrega7on Reproduce the mix design! Types of Facilities Batch Con6nuous (drum- mix) Combina6on Batch Plant 1
Batch Plant Elements Batch Tower Flow Batch tower Across screen deck Storage silos Aggregates travel up hot elevator Screens separate size Hot bins storage tanks Dryer Cold feed bins RAP bin Control room Aggregate from dryer Aggregate weigh hopper Pugmill weigh bucket HMA dispensed into truck Drum-Mix Plant Drum-Mix Plant Storage silos storage tanks Dryer/mixer Control room RAP bin Cold feed bins 3 rd Generation Technology Batch or Drum-Mix? Batch Plant More versa6le More expensive Sta6c weighing Semi- permanent Drum Plant Less expensive High output Weighs moving, wet aggregate More portable Both make quality mix Choice based on business decision 2
Horizontally Stockpiled Aggregate Store Component Materials Stockpile Contamination Avoid Contaminated Material Paved & Sloped Area Covered Stockpiles 3
12/9/14 Binder Storage Vertical Tanks Cold Feed Bins Store Component Materials Combine aggregates in proper propor6ons Ver6cal Dividers Cold Feed Bins Cold Feed Bin Belt Bin Feed is determined by: Gate Opening Belt Speed 4
Collector Belt Collector Belts/Conveyors Collects material and transfers to dryer Cold Feed Bin Feeder Dryer Belt Scale Collector Belt Plant Computer Single Deck Scalping Screen Store materials Combine aggregates in proper propor6on Heat And Dry Aggregates Two Types of Dryers Aggregate Dryers Gas or liquid fueled burner Removes moisture from aggregate Surface and internal Heat aggregate to produc6on temperature Super- heat aggregate for heat transfer to cooler RAP being blended Aggregate & Air Parallel- flow Same direc6on Counter- flow Opposite direc6on 5
Parallel-Flow Drum-mixer Zones Counter-Flow Drum-mixer Zones Air Combustion Heating Drying Mixing Mixing Combustion Heating Drying Aggregate Air Hot Mix Liquid Feed AC Hot Mix Emission Control Equipment Insufficient Drying Exhaust Fan Captures Dust From Plant & Silo Trapped moisture Poor asphalt - aggregate bond Tender mixes Rapid heat loss after mixing content errors Provides Air for Combus6on Evacuates Gases & Steam Insufficient Heating Poor mixing Rich and lean spot Uncoated Aggregate Poor compaction Insufficient heat transfer to RAP Store Component Materials Combine aggregates in proper propor6ons Add liquid binder in proper propor6ons 6
3 rd Generation Technology Store Component Materials Combine aggregates in proper propor6on Add liquid binder in proper propor6ons Mix to coat aggregates uniformly 3 rd Generation Technology Basic Functions of Plants Store component materials Combine aggregates in proper propor7ons Add and mix liquid binder in proper propor7ons Coat aggregates uniformly Store mixture and load trucks without segrega7on Stationary Silo Installations Truck Loading Proper loading of trucks helps reduce segrega7on 3 1 2 7
Truck Loading Truck Loading Use mul6ple drops Loading sequence: Front 25-75% Use mul6ple drops Loading sequence: Front Back 25-75% 1 1 2 Truck Loading Haul Trucks Use mul6ple drops Loading sequence: Front Back Middle Always transfer in bulk 25-75% Clean, smooth beds Approved release agent No diesel! Insulated & tarped Front, sides, bo]om Thin overlays, long hauls, cold weather 1 3 2 Questions? Store Materials Combine aggregates in proper propor6ons Add and mix liquid binder in proper propor6ons Mix and coat aggregates uniformly Store mixture and load trucks without segrega6on 8