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Appendix No. “B”

Types of Deficiencies that May Be Encountered in Producing Asphalt Concrete

POSSIBLE CAUSES Excessive Aggregate Moistures Inadequate Separation at Bins Aggregate Feed Gates not Properly Set Over Rated Dryer Capacity Dryer Angle to Steep Improper Dryer Operation Temperature Indicator Not Adjusted Properly Aggregate Temperature too High Screens are Worn Out Faulty Screen Operation Bin Overflow not Functioning Bins Leaking Segregation of Aggregate in Bins Carryover in Bins due to Overloaded Screen Deck Aggregate Scales out of Adjustment Improper Weighing Procedures Feed of Mineral Filler not Uniform Insufficient Aggregate in Hot Bins Improper Weighing Sequence Insufficient Asphalt Too Much Asphalt Faulty Distribution of Asphalt to Aggregate Asphalt Scales out of Adjustment Asphalt Meter out of Adjustment Undersized or Oversized Batch Mixing Time Incorrect Improperly Set or Worn Pugmill Paddles Faulty Dump Gate Asphalt & Aggregate Feed not Synchronized Occasional Dust Shakedown in Bins Irregular Plant Operation Faulty Sampling

A A A

A = Applies to Batch and Continuous Plants

PROBLEMS Asphalt Content does not Match Mix Design Aggregate Gradation does not Match Mix Design Excessive Fine Aggregate in AC Mixture Uniform Mix Temperature Difficult to Maintain Truck Weights do not Check with Batch Weights Excess Asphalt on Mix in Hauling Vehicle Excess Dust on Mix in Hauling Vehicle Large Aggregates are Uncoated Mixture in Truck is not Uniform Mixture in Truck Rich (Too Much Asphalt) on One Side Mixture Flattens in Truck Mixture Burned Mixture too Brown or Grey (Not Fully Coated) Mixture too Rich (Too Much Asphalt) Mixture Smokes in Back of Truck Mixture Steams in Back of Truck Mixture Appears Dull in Back of Truck

A

A

A

A

A AA AA

A

B

AAC A

BB

CA

AAAAA

AB A AB A AB B B A A A AB A AB B B A A

B

B

B

BB BB

C

ABCBBA C A ABC BABCAA AAAA A A AB A AB B B A AB B A BBA AABCB A A A A A A A C A AAA AAAA BCB AABCB C C AAB A A BA AB A A A AAA AAAA AAA BA A C = Applies to Continuous Plants AA B = Applies to Batch Plants

AAABCBBA

C

A

B AABCB

A

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