SLIDE 1 2018 ARDOT RESEARCH CONFERENCE
50-Year Concrete Pavements
Jamshid Armaghani, Ph.D., P.E. Global Sustainable Solutions Jamshid@bellsouth.net Michael Ayers, Ph.D. Global Pavement Consultants mayers@globalpavements.com
SLIDE 2 150 yrs. 20 yrs.
- Tunnels are designed for 150 years.
- Bridges are designed for 50 years.
Why are pavements designed for 20 years?
SLIDE 3
- Both asphalt and concrete pavements are
designed for 20 years, based on a 20-year projected traffic.
- Asphalt is resurfaced after 8-14 years,
and, in many cases, carry well below the 20-year design traffic.
- Most concrete pavements outlast their
design life before 1st rehabilitation, and carry much higher traffic than designed for.
Asphalt & Concrete Pavements
SLIDE 4
Examples of Long-life Pavements
US 17 Deland > 75 yrs. Brickell Ave. Miami > 75 yrs. I-75 Tampa – 32 yrs. US 1 Whitetopping – 30 yrs. I-75 Tampa – 32 yrs.
SLIDE 5 Factors Contributing to PCCP Longevity
- AASHTO procedure produces conservative
thickness designs.
- Concrete strength is much higher than
specification requirement.
- Joints are dowelled, joint width is narrower
and spacings shorter, and less expansion joints.
- Uniformly placed and compacted support
layers, more permeable. No pumping.
- More automation and innovations in the
construction.
SLIDE 6
Above factors produce less critical stresses responsible for premature cracking, much longer fatigue life & smoother, quieter pavements. Such conditions ensure long-life concrete pavements requiring minimum, if any, rehabilitation.
SLIDE 7
It is time to specify 50-year concrete pavements!
Jointed Reinforced Precast
SLIDE 8
50-Year Concrete Pavements:
Highest quality pavements. Would require minimum, if any, rehab. in first 30 years of service life. Used in select strategic highways that carry heavy traffic. Initially, would be most suited for DB or PPP projects. Justified higher initial cost based on longevity, cost savings in less rehabilitation, less traffic delays and more accident prevention.
SLIDE 9
Research Needs/ Dept. Actions
Selection criteria for project contracted conventionally or through PPPs Revisions in pavement design utilizing AASHTO ME. Emphasis on design details, accurate traffic projections, base materials selection, and geometric details. Upgrade concrete specifications, and develop concrete mixtures compatible with long–life pavements with emphasis on higher level QA/QC and testing requirement.
SLIDE 10 Research Needs/ Dept. Cont.
Best practices manual for construction, with more emphasis on equipment type and proper
Testing protocol for performance related
- indicators. Example: strength, durability,
thickness, bar alignment, texture quality, and surface smoothness. Criteria for qualification of designers, contractors, materials testing services and inspection team on long-life projects. Training program for all project personnel including designers, material suppliers and construction project personnel.
SLIDE 11 Concrete Mix For Long-life Pavements
- Recommended -
- ≥ 4000 psi
- 500 – 600 lb w/SCMs
- Well‐graded total
aggregate system. (Shilstone method)
(slipform)
- Shrinkage test & limits
- Coefficient of thermal
expansion test
SLIDE 12 Design Requirements
- Design firms to demonstrate high level of
experience in designing major concrete pavements
- The Department would be open and encourage
value engineering and innovative, verifiable designs.
- Pavement thickness, support layer materials and
jointing details must produce low pavement stresses, high drainability, long fatigue life and long‐term smooth and quiet surface.
- Independent review of the design by the
Department and/or a third party consultant to assure constructability and long‐term performance.
SLIDE 13 Construction Requirements
- Contractors with track record of successful completion of
high‐quality concrete paving projects.
- The Department would allow value added proposals and
proven innovative construction methods.
- Concrete specifications would be modified to require
more engineered concrete mixes, not only judged by strength but also shrinkage and thermal properties.
- More quality control on paving equipment, surface finish,
timely joint‐sawing, and pavement curing.
- Emphasis on field QC tests for concrete, dowel alignment,
thickness, and surface smoothness.
- Protocol for slab replacement and other actions in case of
premature cracking or other paving deficiencies.
SLIDE 14
Quality Issues in Construction of Long-Life Pavements
Ensure Proper Placement!
SLIDE 15
Avoid Mix Segregation During Paving
Cohesive mix discharged from a low altitude
SLIDE 16
Stringless Control System of Paving Machine
SLIDE 17
Stringless Paving
SLIDE 18
QC of paving machine with dowel/tie bar implants to avoid misalignment mishaps
SLIDE 19
Dowel Alignment Evaluation – MIT Scan
SLIDE 20
Surface Profile Measuring Device
SLIDE 21 Proper Curing
texturing is complete.
coverage of surface and sides.
sprayer.
intermittently for 1st 48 hours.
SLIDE 22
Maturity Device to determine joint sawing time
SLIDE 23
Narrow vs. Wide Joints
Narrow joints ≤ ¼” produce quieter pavements Joints > ½” generate noise for life
SLIDE 24
- The concept is a change in mindset.
- Represents more awareness to
quality.
- Encourages better training for
project personnel in design, construction, testing and inspection.
- Demands overall quality of
construction practices.
- Produces sustainable and resilient
pavements.
- Can be cost effective with time.
50-Year Concrete Pavements
SLIDE 25
