Table of Contents

7.3 Checklists

Checklists for routine inspection of both batch and continuous drum mixing plants are provided in Table 7.1 and Table 7.2 respectively.

Table 7.1: Routine inspections for batch mix plants

Process Checklist
Cold feed
  • Stockpile construction, separation, labelling and handling
  • Source of aggregate
  • Stockpile contamination
  • Aggregate gradation and moisture content
  • Aggregate levels in bins
  • Calibration and setting of cold feeders
  • Rate of feed in relation to the rest of the plant
Dryer and dust collector
  • Accuracy of temperature measuring device
  • Efficiency of the dust collection system and either the disposing of collected fines or feeding uniformly into the mix at the predetermined rate
  • Temperature of aggregate
Screens and hot bins
  • Screen capacities in relation to the rest of the plant
  • Pegged or clogged screens
  • Damage (including holes) and degree of wear of the screens
  • Excessive or irregular carryover
  • Operation of overflow vent
  • Bin levels
  • Sampling point
  • Temperature of aggregate
  • Moisture content of aggregate
Binder heating, circulation and storage
  • Quality of binder
  • Quantity of binder in storage
  • Temperature of binder
  • Sampling point
  • Leakage in lines and at pump flanges
  • Circulation system (including continuous stirring within the tank only for modified binder)
Proportioning and mixing
  • Maintenance, calibration, accuracy and sensitivity of scales
  • Tare mass of binder bucket
  • Temperature of aggregates and binder
  • Proportioning of materials
  • Binder cut-off valve
  • Leakage from binder bucket or aggregate weigh hopper
  • Batching sequence and size
  • Introduction of filler
  • Aggregate distribution in the mixer
  • Uniformity of distribution of binder into the mixer
  • Dry mixing time
  • Wet mixing time
  • Pugmill condition and operation, including paddle tips and dead spots
  • Appearance of the mix
  • Confirmation of grading and other target properties of the asphalt

Table 7.2: Routine inspections for continuous plants

Process Checklist
Cold feed
  • Stockpile construction, separation, labelling and handling
  • Source of aggregate
  • Stockpile contamination
  • Aggregate gradation and moisture content
  • Aggregate levels in bins
  • Calibration and setting of cold feeders
  • Rate of feed in relation to the rest of the plant
Dryer and dust collector
  • Accuracy of temperature measuring device
  • Efficiency of the dust collection system and either the disposing of collected fines, or whether they are being fed uniformly into the mix at the predetermined rate
Binder heating, circulation and storage
  • Quality of binder
  • Quantity of binder in storage
  • Temperature of binder
  • Sampling point
  • Leakage in lines and at pump flanges
  • Circulation system (including continuous stirring within the tank only for modified binder)
Proportioning and mixing
  • Calibration and setting of aggregate and mineral filler feeders
  • Calibration and setting of binder pump
  • Temperatures of aggregate and binder
  • Interlock of aggregate and binder feeders
  • Temperature of produced mix
  • Appearance of mix
  • Confirmation of grading and other target properties of the asphalt