What is Epoxy Asphalt?

Epoxy Asphalt installed without closing to traffic
Epoxy Asphalt installed without closing to traffic
Laying the leveling course

The two-component Epoxy Asphalt binder, when cured, becomes a two-phase epoxy polymer that contains an asphalt extender. The continuous phase is an acid cured epoxy and the discontinuous phase is a mixture of asphaltic materials. It is a thermoset polymer (it will not melt). This binder, combined with high quality standard asphalt paving aggregates in a dense graded paving mix, forms an impermeable tough polymer concrete called Epoxy Asphalt Concrete. A hot spray application of an Epoxy Asphalt bond (tack) coat precedes the laying of the Epoxy Asphalt Concrete to provide a very high strength bond to the substrate (concrete, steel or asphalt) that won’t melt.

Advantages

Typical bridge deck installation of Epoxy Asphalt involves 2 lifts of paving
Typical bridge deck installation of Epoxy Asphalt involves 2 lifts of paving

Fatigue Resistance

The excellent fatigue resistance of Epoxy Asphalt enables it to maintain its integrity on orthotropic steel bridge decks without cracking even after the deflections caused by millions of wheel loads. The fatigue resistance is 3-4 orders of magnitude (of fatigue load cycles) higher than polymer modified asphalt binders. The composite action of the epoxy asphalt, unlike that of more flexible pavements, increases the fatigue life of the steel deck and structure by reducing deflection, and thus strain, in the steel.

Corrosion Protection

Epoxy Asphalt provides another layer of corrosion protection for the steel deck in addition to the primary corrosion protection coating because of its low void content of less than 3%. The voids that exist are not interconnected. The result is an impervious (non-porous) pavement with extreme resistance to penetration of water and chloride ions. The non-permeable properties of Epoxy Asphalt pavement have been verified by third party labs using  AASHTO Test Method T259 (Resistance of Concrete to Chloride Ion Penetration).

Resistance to Rutting and Shoving

Epoxy Asphalt chip seal applied to orthotropic steel deck section for the Golden Gate bridge
Epoxy Asphalt chip seal applied to orthotropic steel deck section for the Golden Gate bridge

Because Epoxy Asphalt binder is a thermoset polymer (as opposed to a thermoplastic polymer such as conventional and rubber-modified asphalt), it provides excellent resistance to rutting and shoving even under high wheel loads in hot and cold climates. The new generation Type IX Epoxy Asphalt has exhibited world record Marshall strengths of >100 kN for a flexible pavement in several recent applications.

Skid Resistance

Epoxy Asphalt pavements include high quality, polish resistant aggregates that provide outstanding skid resistance throughout their life. The Epoxy Asphalt binder does not “bleed” as do thermoplastic bituminous paving materials when the pavement gets hot. As soon as the binder on the aggregate exposed to traffic wears off, vehicle tires see only the aggregate.

Oxidation Resistance

transverse (side) view of orthotropic steel deck section showing longitudinal ribs
transverse (side) view of orthotropic steel deck section showing longitudinal ribs

Epoxy Asphalt binders exhibit extremely low rates of oxidation and loss of resiliency unlike standard and polymer modifed binders. Pavements and overlays constructed with Epoxy Asphalt maintain their properties and do not become more rigid (more brittle) with time. These properties have been validated by several OECD research studies seeking a long-lived pavement for busy roads conducted by the International Transport Forum. In addition, New Zealand is using Epoxy Asphalt on their urban motorways as a extended life binder for open-graded porous pavements (with ~20% voids), in an application where the binder is exposed to more air and water by design due to the intentional higher permeability of the pavement.

Delamination Resistance

Epoxy Asphalt pavements include a separate, high strength, temperature resistant (non-melting) bond coat. Unlike regular or polymer modified asphalts, the Epoxy Asphalt bond coat provides a high strength bond to the underlying substrate (concrete or steel) even at elevated temperatures of 158°F (70°C) which can occur on a hot summer day. In some cases, where delamination has been identified previously as a primary cause of failure, the Epoxy Asphalt bond coat has been successfully employed with polymer modified SMA pavements on steel decks.

Minimum Traffic Delays

Epoxy Asphalt bond coat application
Epoxy Asphalt bond coat application
Epoxy Asphalt bond coat is sprayed onto the inorganic zinc-coated deck plates prior to application of a single layer chip seal. The bond coat is about 0.03 inches (0.68mm) thick. This process allows the replacement deck section to be immediately opened to traffic after the old section is removed and replaced (usually at night).

Epoxy Asphalt provides the absolute minimum delays for re-paving (and sometimes re-decking) existing bridges under traffic. An Epoxy Asphalt pavement is ready for traffic in its partially cured state once it has cooled to ambient temperature. The one-day-old uncured Marshall stability of type IX Epoxy Asphalt (measured at 60°C) is generally > 2000 lb (9.4 kN). It develops full strength over two to four weeks depending on average daily temperatures.

Local Paving Crews

Epoxy Asphalt Meter Mix for batch plant component feed
Epoxy Asphalt Meter Mix for batch plant component feed

Local paving crews using conventional asphalt paving equipment install Epoxy Asphalt. ChemCo Systems technical staff provide training and technical support during the project. ChemCo supplies the special blending equipment (meter-mix machine) for the two Epoxy Asphalt components. This special equipment is operated by local labor. There is no need to import specialized labor.

Applications

2nd Yangtze River Bridge
2nd Yangtze River Bridge

Epoxy Asphalt placements on orthotropic steel decks range from the San Mateo-Hayward bridge, paved in 1967, to the SuTong Bridge, which was completed in 2007 and many others [see last table]. The San Mateo-Hayward pavement lasted over 49 years with no maintenance. Orthotropic decks using epoxy asphalt include bridges paved in Canada, Australia, Brazil, China, South Korea, Thailand and Viet Nam. Several bridges have been paved with Epoxy Asphalt and then, after 25-35 years of successful service, re-paved with the next generation version of Epoxy Asphalt. Epoxy Asphalt has been successfully used in climates with winter temperatures below 0°F (-18°C) and summer deck temperatures reaching 170°F (77°C).

Installation

Macdonald Br deck sections with epoxy asphalt chip seal awaiting installation
Macdonald Br deck sections with epoxy asphalt chip seal awaiting installation

The concrete deck of the heavily traveled Golden Gate Bridge was replaced and paved with no daytime lane closures. Lane shutdown began at 8 PM, paving began at 10 PM and all lanes were opened at 5 AM the next morning. Throughout the night at least one lane was always open in each direction for traffic. Epoxy Asphalt technology helps meet the challenge of replacing old concrete bridge decks with orthotropic steel decks while minimizing traffic interruption. Shop applied Epoxy Asphalt Chip Seal provides a durable skid resistant surfacing that protects each steel plate from wear and corrosion until all plates are in place and welded together. This technique was recently employed on the Macdonald Bridge in Halifax, Nova Scotia during a deck replacement project and the bridge remained open to traffic during daytime commute hours. Epoxy Asphalt concrete provides the long term wearing surface when it is installed after all deck plates are in place. Both the Golden Gate Bridge and the Lions Gate Bridge used this system for their deck replacement projects. The Macdonald Bridge also used Epoxy Asphalt chip seal on the replacement deck sections and a smaller tan-colored aggregate gradation in the Epoxy Asphalt tack coat surfacing for its sidewalks and bikeways as shown on the sides of the 3 lane roadway in the image above.

Epoxy Asphalt Concrete vs. Asphalt Concrete

 

PropertyTest Method (ASTM)Asphalt ConcreteEpoxy Asphalt
Marshall Stability @ 140°F, lb.D15592,50022,000
Marshall Stability @ 400°F, lb.D1559melts8000
Flow value @ 140°F, in. D15590.110.08
Recovery % min. D1559060
Compressive strength @ 77°F, psiD6953400
Comp. modulus of elasticity @ 77°, psiD695167,000
Flex. modulus of rupture @ 77°, psiD293 81640
Flex. modulus of elasticity @ 77°, psi D293380,000
Max. deflection, inchD2930.10.15
Air voids, %D20413 to 5 1 to 2

Epoxy Asphalt Binder & Bond Coat (neat)

 

PropertyTest Method (ACI)ValueFailure Location
Tensile Bond Strength to Inorganic Zinc Coated Steel, psi, (mPa)ACI 503R500, (3.4)Bond Coat
Tensile Bond Strength to Portland Cement Concrete, psiACI 503R350Portland Cement Concrete

Fatigue Resistance

fatigue test of Epoxy Asphalt composite specimen on Instron E10000
fatigue test of Epoxy Asphalt composite specimen on Instron E10000

Properly designed Epoxy Asphalt Pavements for orthotropic steel bridge decks provide a durable surface that resists fatigue cracking in the pavement in the negative moment area above the longitudinal stiffeners. Additionally, the pavement, acting as one element in the composite deck system, reduces deck deflection under load and thus increases the fatigue life of the steel deck plate itself.

On many projects, ChemCo Systems labs can provide accelerated cyclic fatigue testing by making composite specimens to match the design of a specific deck. The composite specimen uses the same pavement thickness and number of lifts as called for and then loads the specimen at 10 hertz cycles to simulate the highest axle loads (including an overweight factor) expected.

Deck Deflection Comparison1

 

Load, kN
Load, kN1.02.03.04.05.06.07.08.0
Deflection, Bare Steel Plate, mm0.060.160.260.36 0.460.570.670.78
Deflection, Epoxy Asphalt/Steel Composite, mm0.030.120.180.260.340.42 0.510.60

Dynamic testing conducted in independent civil engineering laboratories have shown that Epoxy Asphalt pavements resist fatigue cracking over a wide range of conditions. The following table summarizes recent results.

Fatigue Test Results of Epoxy Asphalt — Steel Deck Composite 1,2

 

Temperature, °CStatic Deflection, mm Dynamic Deflection, mmCycles to Failure
00.250.0212x106 with no failure
180.350.1812x106 with no failure
600.610.5812x106 with no failure

Above test results from Southeast University, Nanjing, China, 2000

1. Test specimen: 14 mm plate 100 mm wide, center point load from underside.
2. Test load: 5kN load @ 10 Hz frequency

Left: Fatigue test setup in dynamic testing machine for 18°C test.
Right: Environmental chamber for fatigue tests at 0 and 60 °C

History of Epoxy Asphalt Pavements: over 65 bridges and 450 km of bridge lanes paved

 

Name of bridgeLocationDateDeck TypeArea sq.feetArea sq.meterApprox.Tons
San Mateo-HaywardSan Mateo, CA19679/16" O-T Steel430,00039,9485,495
San Diego-Coronado San Diego, CA19693/8" O-T Steel116,00010,7771,482
San Francisco- Oakland Bay Bridge San Francisco, CA 1969 PC Concrete155,00014,4001,981
McKay Halifax, N. S. 19703/8" O-T Steel128,00011,8921,636
Queensway ALong Beach, CA1970O-T Steel96,0008,9191,227
MacDonald Halifax, N. S. 1971Conc. Filled StI. Grid Main Span119,00011,0551,521
Ross IslandPortland, OR1972 PC Concrete146,00013,5641,866
Evergreen PointSeattle, WA1972PC Concrete270,00025,0843,450
Sellwood Portland, OR 1973 PC Concrete47,0004,366601
Fremont Portland, OR 19735/8" O-T Steel155,00014,4001,981
Costa de Silva (Rio-Niteroi) Rio de Janeiro, Brazil 1973 3/8" O-T Steel220,00020,4392,811
1-94 BridgesMinneapolis, MN 1973 PC Concrete99,0009,1971,265
Mercer Montreal, Quebec1974 3/8" O-T Steel21,0001,951268
Lions Gate Vancouver, B. C. 197515/32" O-T Steel77,0007,154984
San Francisco-Oakland Bay BridgeSan Francisco, CA (lower deck of 2)1976 PC Concrete1,475,000137,032137,032
SF Bay Br.2nd deck (upper)1977lightwt concrete1,290,000119,845116485
Luling New Orleans, LA 1983 7/16" O-T Steel219,000219,0002,799
Ben Franklin (deck replacement) Philadelphia, PA19865/8" O-T Steel632,00058,7158,076
Golden Gate (deck replacement)San Francisco, CA19865/8" O-T Steel576,00053,5127,361
McKayHalifax, N. S.19903/8" O-T Steel128,00011,8921,636
San Diego-CoronadoSan Diego, CA19933/8" O-T Steel1,65015321
ChamplainMontreal, Quebec19933/8" O-T Steel200,00018,5812,556
Maritime Off-RampOakland, CA19965/8" O-T Steel69,0756,417883
2nd Yangtze BridgeNanjing, China200014 mm(approx. 9/16") O-T Steel548,52750,9607,014
Lions Gate Bridge (deck replacement)Vancouver, B.C.2002O-T Steel77,0007,154700
TaoyaomenZhoushan, China200314 mm O-T Steel278,17325,8433,557
Runyang Cable-stayZhenjiang, China200414 mm O-T Steel308,34828,6463,943
Runyang SuspensionZhenjiang, China200414 mm O-T Steel572,64653,2017,323
DaguTianjin, China2004O-T Steel66,6406,191833
3rd Yangtze BridgeNanjing, China2005O-T Steel525,06648,7806,714
PingshengNanjing, China200614 mm O-T Steel525,06648,7806,714
Zhanjiang BayZhanjiang, China2006O-T Steel169,47415,7452,167
FenghuaTianjin, China2006O-T Steel13,1321,220168
NanhuanBeijing, China2006O-T Steel115,62610,7421,479
SutongNantong, China2007O-T Steel764,00070,97810,943
Hangzhou Bay (2 bridges)Ningbo, China2007O-T Steel737,32768,5009,429
YangluoWuhan, China2007O-T Steel521,71548,4696,671
HouhaiShenzhen, China2007O-T Steel44,9104,172574
Fu Ming, Chin Feng, Li Gong, Si HaiTianjin China2007O-T Steel138,43912,8611,770
Huang Pu (2 bridges)Guangzhou China2008O-T Steel556,83051,7318,700
Xihoumen and JintangZhoushan China2008O-T Steel800,86874,40310,110
3rd Yellow RiverJintan China2008O-T Steel333,97631,0274,271
YuZuiChongqing China2009O-T Steel200,80018,6553,100
BaLingGuizhou China2009O-T Steel261,88824,3304,043
BaishazhouWuhan China2009O-T Steel378,88835,2008,786
XiangluowanTianjin China2009O-T Steel31,6092,937486
Thuon PhuocDaNang Viet Nam2009O-T Steel84,3687,8381,079
BanpaldBangkok Thailand2009O-T Steel40,9223,802523
Pong PechBangkok Thailand2009O-T Steel40,9223,802523
Rama IVBangkok Thailand2009concrete54,5625,069698
E'dong BridgeHu Bei, China2010O-T Steel258,28723,9963,311
Jing yue BridgeHu Bei, China2010O-T Steel403,54437,4916,243
Qing dao Bay Bridge (2 bridge spans)Qing Dao, China2010O-T Steel517,16048,0468,000
Chong Qi BridgeJiang Su, China2011O-T Steel265,296265,2964,100
South Train Station BridgeNan Jing, China2012O-T Steel275,55125,600 4,257
Fremont BridgePortland, OR20125/8" O-T Steel176,28716,3782,253
Jiu jiang Second BridgeJiang Xi, China2013O-T Steel358,45733,3025,543
Huang yi BridgeSi Chuan, China2013O-T Steel100,0979,2991,543
Tao hua yu BridgeZheng Zhou, China2013O-T Steel237,60422,0743,671
San Francisco-Oakland Bay BridgeSan Francisco, CA2013O-T Steel358,95333,3483,900
Ulsan Grand HarborUlsan, Korea2014O-T Steel247000230002875
DandeungGunsan, Korea2015O-T Steel8600080001000
Jishan-HaiheTianjin, China2016O-T Steel140000130001841
XinshijiTonglio, China2016O-T Steel8400078001105
Macdonald (in-service deck replacement)Halifax, Canada2016-18O-T Steel890008261725
New Millennium (Saecheonnyeon)Shinan, Korea2018O-T Steel207130192502478
TianxingzhouWuhan, China2019O-T Steel206000191502700