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What is slipping through your fingers?CalAPA Spring Conference April 15, 2015
Steve Marvin, P.E.
Design◦ Structural needs
Asphalt concrete thickness
◦ Support features
Selected mix◦ Performance characteristics
◦ Layer thickness constraints
◦ Aesthetics
Bid◦ Lowest qualified bidder
Project Management Team in Place◦ Inspection team in place
Field
Plant
Field conditions◦ Project management
◦ Inspection
◦ Testing
Weather◦ Project management
Hot mix asphalt/asphalt concrete◦ Aggregate gradation
◦ Selected binder type
◦ Virgin v recycled
Asphalt rubber hot mix/rubberized hot mix asphalt ◦ Aggregate gradation
◦ Binder type
Warm mix asphalt◦ Method
Asphalt concrete plants
Batch type plants◦ Single batch
◦ Continuous batching
Batch type plants◦ Single batch
Drum drier plants◦ Variations
Drum type plants
Aggregate
Binder
Heat◦ Dry aggregates
◦ Heat aggregates to mixing temperature
Mass flow
Multiple aggregate sources
Binder types◦ PG Graded
◦ Polymer modified
◦ Rubber modified
Recycled materials◦ Asphalt concrete
◦ Tires
◦ Roofing materials
Recycled materials◦ Portland cement concrete
◦ Glass
◦ Toilets
◦ Miscellaneous ‘waste’ materials
Warm mix asphalt ◦ Additive based
◦ Water/foam based
◦ Hybrid water/foam/additive
Pro-active ◦ Mix production verification
Cross check
Mix design verification
◦ Real time information (almost)
◦ Permits changes with limited exposure
Things that cannot be verified post construction◦ Production temperature
◦ Raw material condition/handling
◦ Truck conformance/Condition
Things that cannot be verified post construction (cont’d)◦ Recycled materials
Amount
Condition
Fractioning
Binder substitution
Things that cannot be verified post construction (cont’d)◦ Asphalt rubber hot mix/rubberized HMA
Binder properties
Production temperature
Aggregate gradation testing
Ignition oven calibration
Uniform sampling and testing processes
MPQP – Material Plant Quality Program◦ http://www.dot.ca.gov/hq/construc/hma/MPQP.pdf
Plant provided laboratory◦ Space and equipment
◦ Technician assistance
Plant access may be limited
Equipment/testing overlap
Advanced electronics
Verify job shipping information
Check plant for appropriate seals and calibrations
Inspect trucks for condition
Witness initial material production
Verify mixing temperature and product temperature
Initiate plant sampling
Initiate plant sampling◦ Aggregates
◦ Binder
◦ Completed mixture
Perform aggregate gradations
Determine binder content
Verify conformance
Inform plant of findings
Repeat plant sampling◦ Aggregates
◦ Completed mixture
Perform aggregate gradations
Determine binder content
Verify conformance
Inform plant of findings
Develop binder calibration samples
Determine Hveem maximum density and stability
Determine binder content
Why do we perform asphalt plant inspection?◦ Team effort
Verify
Mix being used
Verify
Production conditions
Verify
Truck/release agent/tarp use
Verify
Plant quality control
Why do we perform asphalt plant inspection?◦ Eliminate questions that cannot be answered later
Recycled materials –
Yes
No
What kind
Condition/handling
How much
Why do we perform asphalt plant inspection?◦ Eliminate questions that cannot be answered later
Mixing temperature
Virgin v recycled
Warm mix v hot mix
Binder processing
Asphalt rubber binder production
Obtain calibration samples for future testing
Aggregate
binder
Why do we perform asphalt plant inspection?
INCREASE TEAM PERFORMANCE
REDUCE RISK
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