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Durable pavement for Steel Decks

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Presentation on theme: "Durable pavement for Steel Decks"— Presentation transcript:

1 Durable pavement for Steel Decks

2 History late 1950s Shell Oil develops jet fuel and hydraulic oil resistant paving for airport taxiways. Caltrans uses Epoxy Asphalt on San Mateo- Hayward Bridge (in use). Bay Bridge 18mm overlay on lightweight concrete (in use). Golden Gate Bridge redecked (in use). nd Nanjing (first Asia project). --5th generation product used for the first time

3 Applications Orthotropic steel decks New construction
Replacement paving Re-decking Overlays Temporary chip seals For replacement deck panels High (heavy weight) traffic, strategic roads with long life requirement Fuel and chemical resistant paving Lionsgate Br

4 EA Chemistry Epoxy cross-linked polymer: continuous phase, asphalt: discontinuous phase 2 component binder and 2 component bond coat Part A Resin Part B Asphalts and cross-linkers Ambient temperature reactive cure mechanism Cured polymer is thermoset (won’t melt)

5 Properties Extremely high fatigue resistance High strength bond coat
Protects against delamination Ensures composite action with steel Resists high summer deck temperatures Thermoset Will not melt Higher modulus than other flexible pavements Reduces deck deflection Element meshing “Epoxy Asphalt has a fatigue life of 2 to 3 orders of magnitude greater than the PG76-22 I-5 mix…”. --Rutgers University study

6 Properties Does not oxidize (like all other asphalts)
No embrittlement upon aging Low voids (typically ~2 %) Water impermeable No chloride ion penetration No corrosion--no membrane required High Temperature bond performance FHWA OECD Long Lived Pavement Study Turner Fairbanks Highway Research Center

7 Fundamental difference
HMA Asphalt, SMA, Gussasphalt, PMA are thermoplastics: will melt Epoxy Asphalt is thermoset: will not melt “Epoxy Asphalt concrete has shown excellent performance including anti-cracking feature under low temperature, stability under high temperatures and oil-corrosion resistance.…” --W. Wang, Chang’an University

8 Advantages Low permeability prevents deck corrosion
Fatigue resistance minimizes cracks 4+ times more stability than standard AC Handles truck wheel overloads (common in Asia) --Rutgers Univ.

9 Advantages No rutting or shoving Use standard AC paving equipment
Very high bond strength Paving placement is fast Won’t delaminate “The superior oxidation resistance of the epoxy asphalt material was even more obvious in the Cantabro tests…” --Transit New Zealand—OECD report

10 Typical new construction detail

11 EA Specifications Dense graded mix, ½” (12mm) minus
Basalt rock for skid resistance and long wear Low temperature paving ( ºC) Time/temp monitoring is critical QC element Similar temps to warm mix Lab simulation (fatigue testing) advised for unique decks

12 O-T Deck Pavement Stress from wheel load deflection
Longitudinal stiffener TENSION

13 Fatigue testing evaluate pavement design on project specific deck
Keys Realistic paving composite specimens Good tests take time Research performance of local materials (aggregates) Use environmental chamber to control extreme temps

14 Comparison: EA vs. polymer modified AC or SMA
Properties Condition Epoxy Asphalt Polymer AC High temperatures Will not melt Melts Permeability None measurable Changes with age a. Will not oxidize b. Flexibility constant No age related performance losses Oxidizes Flexibility declines Delamination potential Very low Consistent composite behavior High Fuel resistance Low—will soften and dissolve binder Rutting, shoving Stable Unstable under high temps and loads

15 Chinese standard deck detail
Fatigue test specimen with 3 pt. dynamic load on 300 mm center 300 mm stiffener spacing 12 mm deck plate (prior to 1999) 14 mm deck plate (after 1999) 50-55 mm EA paving Locus of highest stress is over stiffeners, particularly in truck lanes Dynamic fatigue test is good predictor

16 Asian conditions High deck temps To 90 °C
Extreme temperature cycle between winter and summer Construction QC varies widely Standardized deck design in mainland

17 Asian conditions Consistent very high truck wheel overloads
To 120 MT on 18 wheelers SMA and gussasphalt sometimes fail as quickly as 2-3 yrs. SuTong Br.

18 EA: Disadvantages Time and temperature controls critical
Controls can lead to higher quality and uniformity Paving plant needs to be within minute drive Too complicated Over 35 bridges in Asia in past 10 yrs successfully completed including 1st suspension bridge in Viet Nam ChemCo provides advisors Use test section in convenient location to train local paving crews before deck placement Costs more Cost difference dwarfed by frequent closures and repaving Thuan Phuoc Bridge DaNang, Viet Nam

19 Next in N. America Fremont, Portland 2011 MacDonald, Nova Scotia ~2015
Repave in July MacDonald, Nova Scotia ~2015 Redeck similar to Lionsgate San Francisco-Oakland Bay ~2012 Single anchored suspension (new East Span)

20 Future Reduce pavement weight
Local manufacturing OECD-ECMT Joint Transport Research on long life pavements (U.S., U.K., France, Germany, Denmark, New Zealand, Australia) Open graded performance benefits demonstrated Improve fatigue performance in most challenging applications Decks with extremely high wheel overloads Decks with thin plates (12 mm) Hottest tropical environments

21 Conclusions Design, test and confirm for wear course success
Epoxy Asphalt, a thermoset material, performs on challenging decks Epoxy Asphalt offers life cycle cost benefits Asian lessons learned Over design surfacing when realistic data not available Be flexible to adopt local improvements

22 Thanks for your interest!

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