For ORTHOTROPIC STEEL BRIDGE DECK PAVEMENTS

Epoxy Asphalt vs alternatives(SMA and gussasphalt)

History—Orthotropic decks

EUROPE  1950

NORTH AMERICA  1964

ASIA  1979

Problems on Steel Decks

RUT/SHOVE CRACK DELAMINATION

Most Frequent = Cracks Over Longitudinal Stiffeners

Cracks Lead to Disbonding Most Severe in Hot Weather

Rutting and Shoving

Fatigue Cracks

Longitudinal stiffeners (ribs)

STIFFENER

TENSION

Wheel load deflection

Epoxy  Asphalt (EA) since 2000

40+ bridges selected EA, most in Asia Over 800,000 m² of Deck Longest span suspension bridge in China First suspension bridge in Viet Nam

Long lived EA pavements

San Mateo, 46Golden Gate, 27

Fremont, 39

SF Bay, 37

What is Epoxy Asphalt?

Two‐Component Polymer system

1st Component (Part A) = Epoxy Resin

2nd Component (Part B) = Hardener & Asphalt

With Aggregate = Epoxy Asphalt Concrete

“In 19 years, after approximately 1.5 billion vehicles,…the 19 mm epoxy asphalt surfacing (on the SF Bay Bridge) has good skid resistance and is still performing well.” --C. Seim, ACI SP, 1995

Cured Epoxy Asphalt

A stable and durable “2‐Phase”Polymer  System

Hardener/Epoxy = Continuous Phase

Asphalts = Discontinuous Phase 

Hardener/Epoxy Predominates

What is a mastic?

Mastics (also called gussasphalts) are over‐filled mixes with small aggregates dispersed within binder

No Aggregate Skeleton formed Requires stiffer binders than concretes Tension and compression stresses carried by stiff binder Poured in place under high temperature (240‐260C), no 

compaction Use special heated transport vessels with internal mixing Require friction chips spread over surface and rolled in 

(very low skid numbers without)

Fundamental Difference

Asphalt, SMA, mastic asphalts (gussasphalt) are “Thermoplastics.”

Will Melt !

Epoxy Asphalt is “Thermoset.”Will Not Melt !

Property Comparison

Epoxy Asphalt has: Higher Strength/Stability Better Stiffness over Temperature Range Better Resistance to Creep/Flow Better Adhesion

‐versus thermoplastic asphalts

Higher Strength/Stability

Greater than Four Times Stability of Mastic

Withstands Higher Overloads without Damage

Does Not Rut or Shove

“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

Flexural Strength

Flexural Modulus

MPa MPa

Mastic (guss) Asphalt  5.95 563

SMA  4.73 355

Epoxy Asphalt   16.4 2574

HUANG Wei, QIAN Zhendong, CHEN Gang & YANG JunChinese Science Bulletin 2003 Vol. 48 No. 21 23912394

Flexural strength/stiffness at 15°C

Transition Layer Surface Layer Depth – mm

25 mm Epoxy Asphalt 25 mm Epoxy Asphalt 0.32

20‐25 mm mastic asphalt 35‐40 mm Epoxy Asphalt 0.34

25 mm Epoxy Asphalt 30‐40 mm SMA 0.74

30 mm SMA 35 mm SMA 1.05

20‐30 mm mastic asphalt 35‐40 mm SMA 1.74

30 mm mastic asphalt 40 mm mastic asphalt 3.58

Li Xuelian, Zhou Zhigang, Key Laboratory of Highway Engineering, Changsha University of Science & Technology

Rutting test, 70°C

Stiffness Benefits

Less Softening as Temperature IncreasesReduces Deflection of Deck Increases Fatigue Life of Steel Deck System

--Tom Bennert, report for NYNJPA Rutgers Univ.,

2007

Better Resistance To Creep/Flow

Much More Elastomeric Better Fatigue Life

No Permanent Deformation under High Loads Reduced Damage by Slow Moving or Stopped Overloaded Trucks

“The superior oxidation resistance of the epoxy asphalt material was even more obvious in the Cantabro tests…”

--Phil Harrington, Transit New Zealand—OECD report

Fatigue tests

At Service Temperature Extremes

At Expected Overloads

Fatigue testing: composite beam, constant load

Type  V– Standard Epoxy Asphalt

14 mm Plate with 300 mm Wide Stiffeners on 600 mm Centers

Conducted at 0, 18,  60 deg C

10 Hz Frequency

Normal Load & Overload 

NO FAILURE @25 Million Cycles

Fatigue test specimenwith 3 pt. dynamic load

on 300 mm center

Type IX – New Generation Epoxy Asphalt

12 mm Plate with 300 mm Wide Stiffeners on 600 mm Centers

Conducted at 21 deg C

10 Hz Frequency

Normal Load & Overload

NO FAILURE @ >25 Million Cycles

Potential savings in deckplate mass, dead load and suspension steel

“If all aspects of the process are correctly handled, Epoxy Asphalt should be able to provide a surfacing material that can be expected to meet the aim for a much extended practically maintenance free service life, i.e., 30 years or more.”

--Int’l Transport Forum—2008 OECD report

Fatigue comparison ‐ Constant Strain

Pavement Adhesion ChemCo  Bond Coat  Type 1f Pull‐Off Adhesion 2.4 MPa@ 70º CNegligible slippage at bond line assures composite action

No Delamination

High Temperature bond performanceFHWA OECD Long Lived Pavement StudyTurner Fairbanks Highway Research Center

Typical construction detail

Img_0381.jpg

Automated bond coat spray

PROPORTIONS THE TWO BINDER COMPONENTS

MIXES THE COMPONENTS

INJECTS AMOUNT FOR EACH BATCH

Meter mix machine

Batch temperature

Temperature controls

First compaction step must be completed before 82℃

Finish before 65 ℃

Keys to Success

Proper Pavement Design Composite of Deck & Pavement Fatigue Test of System

Strict Quality Control Batch Temperature Control Immediate Compaction to <3% Voids

Cost/BenefitComparison to Mastic Asphalt/SMA

Overall weight savings with potential lighter pavement structure  As much as 10% of box structure weight Lower deckplate thickness possible Fast Installation:  3,000 sq. m. per day Saves waterproofing step

“…epoxy asphalt mixture is much more resistant to low temperature thermal cracking (-30°C) than conventional asphalt concrete mixtures.”

--Mihai Marasteanu, FHWA research report, University of Minnesota, 2008.

EPOXY ASPHALT LIFE = 20 YEARSSMA or Mastic ASPHALT LIFE = 5‐8 YEARS

SMA or GUSSASPHALT COST = XAssume: EPOXY ASPHALT COST = 2X20 YEAR COST

EPOXY ASPHALT = 2X

SMA/GUSSASPHALT = 4X

Lifecycle analysis

EA compared to mastic

Longer Fatigue Life of Steel Deck Composite Action Avoids Traffic Problems of ReplacementDoes Not Oxidize / Retains Flexibility Resists Automotive Fuels and Fluids Provides Impermeable Water Barrier

•EPOXY ASPHALT  IS UNIQUE

•LONG SUCCESSFUL HISTORY

•EXCELLENT RESULTS IN ASIA and N America

•OFFSETS TO HIGHER MATERIAL COST1.   LONG LIFE2.   LOW WEIGHT3.   FAST INSTALLATION

Summary

Thanks for your interest!