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State-of-art of Asphalt surfacings on long-spanned orthotropic steel deck in China
Xianhua C H E N ' , Xueyan Liu^, Zhendong Qian^, Zhang Lei^ 1 School of Transportation, Southeast University, Nanjing, China, 210096
2 CITG, TU Deft, Delft, the Netherland, CN2628 3 ITS Center, Southeast University, Nanjing, China, 210096
Abstract: Reliable and durable asphalt surfacing systems still remain to be desired for the long-spanned orthotropic
steel bridges as the nationally and internationally reports on distresses in deck pavement. Based on ten-year research
works, this paper has presented a brief review and discussion of the Chinese practices and experiences of deck
pavement on long-spanned steel bridges, including issues of typical surfacing materials and their properties, main
distresses in asphalt surfacing, and the basic characteristics of asphalt surfacing on orthotropic steel bridge decks. It is
concluded that the behaviours of deck pavement on oithotropic steel bridge deck under truck load are coinplex
contributed by geometric and material-dependent nonlinearity, coupling the global dynamic effects of the whole
bridge systems. More efficient computational techniques are still desirable to couple global effects into local
responses, to count the interfacial effects and interaction, and to evaluate the effect of predominant distress of fatigue
cracking and de-bonding on the service life of this type of structure.
Keyword: long-spanned steel bridge, orthotropic steel decks; asphalt surfacing system, local deflection behaviour;
composite action; fatigue cracking
1 Introduction
Orthotropic steel deck systems with cross-beams and longitudinal ribs have been widely used in modern long-
span bridges to reduce the weight and depth of the girders[l]. The oithotropic steel deck plate of highway bridges
requires a wearing surface for skid resistance, for smooth riding, and for corrosion protection. The wearing surface is
subjected to the heavy impact of loaded truck wheels imposed by the passage of millions of ti'ucks during the several
decades of its service life, acts as skid-resistant pavement for the vehicles and, as well as load-spreadmg layer and
corrosion protecting layer for the steel superstructure. It should be watertight, resisting cracks and well bonded to
steel deck plate, besides provide a smooth riding surface with high skid resistance for the vehicles passing through the
bridges[2].
Bituminous materials such as gussasphalt or mastic asphalt, epoxy asphalt concrete and Stone Matrix Asphalt
have adopted as the surfacing materials for a long-time as due to their flexibility, deformation compliance and good
water resistance. However, premature distress of asphalt surfacing have been frequently reported world-wide within
recent twenty years, such as cracking of steel deck plates, rutting and cracking of asphalt surfacing materials, loss of
bond between the surfacing layer and the steel bridge decks. The severity of the problems is enhanced by the
considerable increase in traffic in terms of number of trucks and heavier axle loads. Asphalt surfacing acts
compositely with the steel deck plate by the bonding membrane and must be regarded as an integral part of the
structural deck system [3]. A better understanding of the behaviour and the interaction of the surfacing layers and the
steel decks are of paramount importance for the effective design of steel bridges. Innovative methodologies offer
' Corresponding author: Xianluia CHEN(1976-), Ph.D, Associate Professor, Tel.: +86 25 837 90522, Email: chenxhfg.seu.edu.cn Foundation Item: project(50908053) supported by National Natin-al Science and Foundation of China.
opportunities to mitigate material response degradation and fatigue related problems in this type of structures
contributing thus to significant extension of the service life of steel bridges.
In this paper, consideration is given to the requirements for a bright future for the asphalt surfacing on orthotropic
steel bridge decks by carefully analysing recent trends. The state of the art of asphalt surfacing system, and the
considerations towards a bright future in Chinese long-spanned steel bridge construction could be useful also to
various other countries, in particular, countries with heavy duty traffic and long-spanned orthotopic steel bridges.
2. Asphalt surfacing on orthotropic steel bridge in China
2.1 Long spanned steel bridge with orthotropic deck plates
The application of orthotropic steel deck plate in highway bridges in China can be dated back to 1970s. However,
great achievements have been accomplished within twenty years after Xiling Yangtze River Bridge. More than
twenty long-spanned steel bridges with orthotropic deck plates have been constructed to meet the requirements of
rapid economy developments and travel demands.
Table L Cable-supported steel bridges in the mainland of China
Year Main steel box-girder deck trapezoidal ribs original Bridge Name span
(m) length (m)
height (m)
width (m)
plate (mm)
rib wall (mm)
depth (mm)
width at top rib spacing (mm) (mm)
rib span (m)
deck pavement
Taizhou Under constr.
1080x2 2160 3.5 39.1 14/16 6/8 280 300 600 3.2
Xilioumen* 2009 1620 2220.8 3.51 36 14 8 280 300 600 3.6 Figlb
OT <U
Zhujiang Huangpu
2008 1108 1108 3.5 38.6 16 8 280 300 600 3.2 Figlb
brid
g Runyang-South
2004 1490 1490 3 38.7 14/12 6 280 300 600 3.22 Figlb
pens
ion
Yichang Yanbtze
2001 960 1187 3 30 12 6 280 300 590 4.02 Figlc
3 Haicang 2000 648 2000 3 28.8 12 6 280 300 600 3.5 Figlc
Jiangyin 1999 1385 1385 3 36.9 12 6 280 300 600 3.2 Figla
Humen 1997 888 1997 3 33.6 12 8 260 320 620 4 Fig2c
Xiling 1996 900 900 3 21.4 12 6 - 320 640 2.54
Edong 2010 926 901 3.8 38 16 8 300 300 600 3.0 Figlb
Jingyue 2010 816 1204 3.8 38.5 14/16 8 300 300 600 3.0 Figlb
brid
ges Minpu*** 2010 708 708 9 43.6/27 14/16 8 300 360 700 15.1 Figlb
brid
ges
Shanghai Yangtze
2009 730 1430 4 51.5 16 8 300 300 600 3.75 Figlb
•a Jingtang 2009 620 1210 3 30.1 14 8 280 300 600 3.5 Figlb
Cab
le-s
ti
Sutong 2008 1088 2088 4 41 16/14 8 300 300 600 4 Figlb
Cab
le-s
ti
3rd Nanjing 2005 648 1288 3.2 37.2 14/16 8 280 300 600 3.75 Figlb
Cab
le-s
ti
2nd Nanjing 2001 628 1238 3.5 37.2 14 6 280 300 600 3.75 Figlb
Bashazhoii 2000 618 904 3 30.2 12 8 260 320 640 6** iMglc
* 1. Twin-box gu^der; **2. With a hansverse rib in between two adjacent cross-beams; ***3. a.) Mam ghder is truss beam with double decks for highway traffic;
b.) With three transverse ribs in between two adjacent cross-beams;
The deck system of long-spanned steel bridges in China normally consists of a deck plate, 12-14 mm thick and
longitudinal trapezoidal or rounded closed ribs, supported with cross beams spaced from 3.2 to 4.5 m apart, as listed
in Table 1. The steel decks are sand-blasted and then coated with zmc primer and waterproof membrane /bonding
coat prior to the construction of 50-80 mm thick asphah surfacing layers. In order to minimize the fatigue problems
of the superstructure, the deck plate at outside lane of the newly built bridges is thickened even up to 16mm or 18mm.
2.2 Typical structure of deck pavements on orthotropic deck plates
Typical structures of deck pavement used m China are shown as in Fig. 1. Gussasphalt or Mastic Asphalt(MA),
Epoxy Asphalt Concrete(EAC) and Stone Matric Asphalt(SMA) are the commonly candidate surfacing materials for
those steel bridges. Their properties are also different, as illustrated in Table 2 according to the research results of
Southeast University[4].
30-«liiIii SM witli SBS
a) Gussasphalt b)epoxy asphalt concrete c) Stone Matrix Asphalt
Fig. 1 Typical structures of deck pavement used in China
Table 2 Propeities of asphalt surfacing materials used in China
Properties SMAIO GA EAC
Binder content 6.2 8.2 6.1
Air Void/% 3.0 0.6 2.2
Marshall Stability 10 -- 58
Dynamic Stability(60°C,0.7MPa, i:^-mm ') 4846 1276 17671
Flexural strength(-15°C,lmm/min, MP a) 10.31 13.72 24.18
Flexural strain(-15°C,lmm/min, 10'̂ ) 3.09 8.26 3.72
TSR(%) 88.3 95.7 91.8
Expansion at 15°C~-15°C(10-^°C"') 2.25 2.14 1.52
EAC is a thermo-set material by using a reaction-curing material of epoxy asphalt which wil l not inelt or soft under
70°C temperatures, which has been ineasured on orthotropic deck pavement in 2nd Nanjing Bridge. EAC is proved to
be the super durable surfacmg material for heavy duty traffic and extremely high temperahare, and now it is widely
used in China although its construction cost is 2-3 times that SMA. M A are demonstrated suitable for long-spanned
suspension bridges for a better flexibility, compliance and water resistance. The binder of M A are normally Pmb 25
with a soft point higher than 85 °C or straight hard bitumen with penefration grade of 30-40. The blend of natural lake
asphalt is about 10% to 40% dependent on the durability requirements. Warm mixing additive such as organic
polymer wax is also adopted to decrease the viscosity for the purpose of construction.
3 The performance of typical asphalt surfacing system in China
The performances of asphalt surfacing on steel bridge decks in Chhia vary from excellent to poor depending
largely on local climate, deck plate flexibility, volume of heavy truck traffic, and the type and sftucture of the
surfacmg[5]. The main distresses are fatigue cracking, slippage and de-bonding, ruttmg and shoving, and pothole[6].
In general, comparing witli the MA and SMA systems, the performance and condition of EAC systems is better and
its mean service life is much longer than other systems.
3.1 Fatigue Cracking
Fatigue cracking has been recorded in all type of pavement on orthotropic steel bridges decks. These cracks are
located on the surface of the pavements near the conjunction ribs of the longitudinal and transverse stiffeners. The
cracks were observed to propagate in depth and in length fustly, several weeks later, a second parallel longitudinal
cracks could be initiated i f the original one be not been sealed or repaired on time. And alligators or block crackmg
wil l be inevitable within several months, as shown in Fig. 2.
over crossbeam Propagate in Length
Fig. 2 Fatigue Cracking and the propagation of pavements on orthotropic steel decks
3.2 disintegration of slippage and de-bonding
Slippage of deck pavements were mainly observed in the surfacing system of SMA and MA at hot summer. The U-
shaped cracks occur with the corrugation and shoving of the pavement. The cracks generally have a width of 2 cm to
10 cm covering at least lane, as shown in Fig. 3.
Fig. 3 Slippage cracking of SMA asphalt layer
Localized de-bonding has also been observed in the surfacing system of gussasphalt and SMA as shown in Fig. 4.
According to the repairing practice, asphalt layer adjacent the alligators or potholes wi l l lose bonding as water can
penetrate down to steel deck plate surface. Experiences also indicate that large area of the pavements wi l l soon fail
once the deck pavements system loses bond strength at the interface.
Fig. 4 Debonding at the interface of asphalt surfacing and steel bridge decks
3.3 Rutting, shoving and corrugations
Rutting, shoving, and corrugations are common distresses of the surfacing systems with thermal-plastic bmder
such as MA and dense graded asphalt concrete with polymer modified asphalt. Severe rutting has also occurred in the
surfacmg system of SMA. These problems could become even worse as the occurrence of fatigue cracking, the rapid
increase of heavy duty traffic and the absence of efficient fighting against overloadmg, despite of higher performance
grade polymer modified asphalt was adopted or natural hard asphalt was blended.
3.4 Bubbles and hair cracks
Bubbles and irregular micro-cracks were mostly found in the surfacing system of EMA. The bubble can be easily
recognized with two or thi-ee radial micro-cracks as shown m Fig. 5. A ring crack of 15cm to 30cm in diameter wi l l
then develop withm several weeks i f the bubble crack be not properly repaired and sealed, and consequently, a
pothole will form from bubbles as shown in Fig. 5.
Fig. 5 Bubble cracking and development of pothole
hregular micro-cracks have also been observed on the surface of EAC with a length of 5cm to 15cm, as shown in
Fig. 6. This type of cracks may be a conhibution of differential construction temperature and compaction, and
chemical reaction between the cure agent and epoxy resin. However, the real reason is still unknown to us as no
visible feature could be summarized.
Fig. 6 Irregular micro-cracks in E A C
4 The behaviours of Asphalt surfacing on orthotropic steel bridge decks
4.1 general analysis
Considering tiie overall behaviors, the complex stress field in the surfacing of an orthotropic deck is the result of
three actions[3]: (1) Prknary stresses arismg fi'om the mam gh-der effect. These membrane stresses are due to the
bending of the main girder, when the orthotropic deck is simply considered as the upper flange; (2) Secondary
stresses arising fi'om the distribution of the loads correspondmg to the rigidities of the ribs and cross beams; (3)
Tertiary stresses arising from the local bending of the isoft-opic deck plate under dhect wheel loading. To include the
global effects of the cable-supported system and the mam girders, a multi-scale approach[7] has been proposed
recently by the research group of Southeast University, as illustrated in Fig. 7. A 10 to 20 percentage of increase in
maximum transverse tensile stress has been reported according to the analysis of Taizhou Bridge[8].
levels
Fig. 7 A multi-scale approach to simulate the behaviours asphalt surfacing on orthotropic steel
bridge decks[7-8]
4.2 Local responses of asphalt surfacing on steel bridge decks
The behavior of paved steel orthotropic decks under heavy truck traffic and envkomnental conditions is veiy
complex with localization characteristics, and dependent on the geometry of the decks, the wheels position, wheel
footprints, and other uncertain factors. FE-calculations for this study are found time-consuming and the results
obtained are strongly dependent on the geometric configuration of the deck, position of the wheels, and composite
contribution of the surfacing and other uncertain factors [9].
4.2.1 Wheel load positions
One of the characteristics of orthotropic bridge decks is the relatively large local deflection caused by the passage
of fruck wheel loads, as shown in Fig. 8. The transverse stress response of a typical orthotropic deck with varies load
positions are shown in Fig. 9. Load case I (dual-tyre crawls on one rib) and load case I I (dual-tyre crawls on one webs
of a rib) are critical position, under which larger local displacement and transversal tensile stress wil l occur, and in
particular, for negative bending in load case I I . Critical points under different load case with large tensile sti'esses are
shown as in Fig. 10 with red circle marks. Transverse tensile stress occurs at the top of pavement over webs of ribs
adjacent to wheel load, and for longitudinal tensile stress, the max value occurs at the top of pavement over webs of
diaphragms near to wheel load.
load c a s e : I I I
1.1111 H i l l
U U U I W W U Fig. 8 Vertical displacement of deck pavement under dual-wheel load
load c a s e ; I I I
U 'U' U I W 0""W I W J"U V Fig. 9 Transverse Stress of deck pavement under dual-wheel load
J 0 .30
5 0. :o
E
I 0. 10
E 0 .00
£ 0 .70
S 0 .60
I 0 .50
I Q.W
I "-SO
c 0 .20
: 0 .10
g 0 .00
r: 0 . 25 c-Z •J. 0 .20
i • J 0. 15
I 0 .10
I 0 .05
Ê 0 .00
' t i a i i ï v e n a l
- lonojtudinal
0 50 100 150 200 250
D i s t a n c e to the iieai-est diaphgi-aiii , c n i
0 50 100 150 200 250
D i s t a n c e to tlie nearest d i a p h g r a m . c m
0 50 100 150 20O 250
D i s t a n c e to the nearest d i a p h g r a m . c m
Fig. 10 Maximum stress response with wheel load moving along bridge
4.2.2 load effects
As equivalence of multi-axle loads into standard single axle load is a key aspect in pavement design, CHEN and
Qian[10] investigated the equivalent factors of multi-axle loads for pavement on steel bridge decks through the
concepts of axle interaction factors and dissipated energy based on fatigue equivalence principle. The responses of
asphalt pavements on orthotropic bridge decks under single, tandem axle and tri-axles were sunulated with 3-D FEM.
The time history stress response with varied adjacent axle distance has been calculated as shown m Fig. 11. The
effect of adjacent axle on the stress responses can be negligible when the adjacent axle distance of a multi-axle is
great than half span of longitudinal ribs. Three composite beams samples composed of epoxy asphah concrete and
steel plate were loaded with the simulating block loads. The dynamic responses of composite beams were measured
and the dissipated energies of epoxy asphalt concrete were calculated with measured shess-strain hysteresis loops,
shown as in Fig. 12. Equivalent factors of multi-axle loads were determined with interaction factors of different axles
and their dissipated energies as 1.39 and 1.86 for tandem axle and tri-axle respectively.
2 " axle
-0.1 L
Time, X 0.078s
Fig. 11 Time history stress response with varied adjacent axle distance
single axle tandem-axle tri-axle
Fig. 12 Energy dissipation of standards single axle and multi-axle loads in composite beam fatigue test
4.2.3 Temperature effects
Asphalt surfacing, whether theiTnal-plastic materials as SMA or MA, or thermal-setting materials as EAC, are
temperature dependent materials. With temperature changes fi-om high temperature to low temperature, the modulus
of asphah matenals decreases as tested by Xianhua CHEN[11]. Transversal tensile stress, which causes longitudmal
cracks is dominate stress at room temperature to high temperature. However, numerical results reveal that
longitudinal tensile stress becomes critical at low temperature, which wil l contribute to transversal cracks, as shown
hi Fig. 13.
J ^ 4000
3 s i a l i c loadi i i :
20 40
Temperature, "C 200 400 600
Modulus Ratio(Steel/H\lA)
Fig. 13 Temperature effect on modulus of E A C and the maximum tensile stress of E A C system
4.3 Interaction between E A C and steel deck plates
Focuses have been made to the mteraction between asphalt surfacing layers and orthotropic steel bridge decks as
it is also a key factor to the responses of asphalt surfacing layers, as well as to the orthotropic steel decks. As the
behaviour of EAC is to some degrees different with M A and SMA, and the bonding membrane of epoxy asphalt is
totally different with the membrane of rubberized asphalt or mastic asphalt, CHEN and HUANG[11] explore the
interaction of epoxy asphalt surfacmg system hi laboratory. They adopted an equivalent simply supported beam
loaded at mid-span to characterize the local hog moment of surfaced orthotropic deck plate under a double-wheel
load at the critical position. Strain distributions along thickness of the composite beam were tested and the results at
room temperature are shown as in Fig. 14. A new model to describe interface behaviors of simply supported
composite beams was developed by defining a parameter named of bonding membrane stiffiiess incorporated with the
classic linear-elastic partial interaction theory[12]. A simple mathematical procedure was developed and verified to
predict the flexure responses of the beam.
-500 0 500 1000 1500 2000
compressive tensile
.Moasureed s t r a i n (p £ )
Fig. 14 Test set-up of composite beam and the strain distribution of E A C composite beam specimen
5 Conclusion
This paper presented state of the art of asphalt surfacing on long-spanned orthotropic steel bridge decks. Issues of
typical surfacing materials and their properties, mam disfresses in asphalt surfacing, and the basic characteristics of
asphalt surfacing on orthotropic steel bridge decks have been overviewed. The behaviours of deck pavement on
orthoh-opic steel bridge deck under truck load are complex contributed by geometric and material-dependent
nonlinearity, couplmg the global dynamic effects of the whole bridge systems. More efficient computational
techniques are still desirable to couple global effects into local responses, to count the interfacial effects and
hiteraction, and to evaluate the effect of predominant distress of fatigue cracking and de-bonding on the service life of
this type of structure. A successful deck pavement design should be based on sufficient understanding the shuctural
behaviours and proper estimation the environment, traffic and construction conditions. It should also incorporate
pavement design into superstructure design of the bridges. In addition, improvement of the integral performance of
deck pavement, paying much attention to the aspects of construction and ensuring the designed inaterials to be
constructed with designing specification are all important factors to lead to a successftil deck pavement project.
Reference:
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practical design. Structural Engineering International. 2002, (2): 124-129. [4] Huang W., Theory and Method of deck paving design for long-span bridges. Construction
Industry Press, Beijing, China, 2006, 10. (in Chinese). [5] Medani T.O., Design principles of surfacings on orthotropic steel bridge decks. Ph. D Dissertation.
Netherland: Delft tJniversity of Technology, Jan, 2006. [6] Chen X.H. , Huang W., Yang J., et al. Cracking of wearing courses on steel orthotropic bridge
decks, 6''' RILEMInternational Conference on Cracking in Pavements, Chicago USA, June 16-18, 2008.
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[8] Qian Z.D., HUANG W., CHEN X.H. , LUO S., et al. Research on asphalt surfacing for the orthotropic steel decks of Taizhou Bridge[R]. Nanjing: Southeast University, 2011,
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