Evaluation of epoxy asphalt rubber with silane coupling agent used as tack coat for seasonally frozen orthotropic steel bridge decks

Construction and Building Materials 241 (2020) 117957

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Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat

Evaluation of epoxy asphalt rubber with silane coupling agent used as tack coat for seasonally frozen orthotropic steel bridge decks Qibo Huang a, Zhendong Qian a,b,⇑, Leilei Chen a, Meng Zhang c,d, Xiaorui Zhang b, Jian Sun a, Jing Hu a a

Intelligent Transportation System Research Center, Southeast University, Nanjing 210096, PR China School of Transportation, Southeast University, Nanjing 210096, PR China c Research Institute of Highway Ministry of Transport, Beijing 100088, PR China d Key Laboratory of Transport Industry of Road Structure and Material, Beijing 100088, PR China b

h i g h l i g h t s
Epoxy asphalt tack coat modified by silane coupling agent surface-treated rubber particles (ARP) is proposed.
The ARP can improve the pull-off failure resistance and water tightness of EAAR tack coat.
The ARP can significantly improve the shear failure resistance of EAAR tack coat at low-temperature.
EAAR tack coat has superior resistance to recurrent freeze-thaw cycle damage.

a r t i c l e

i n f o

Article history: Received 21 September 2019 Received in revised form 15 December 2019 Accepted 24 December 2019

Keywords: Orthotropic steel bridge deck Tack coat Epoxy asphalt Silane coupling agent Rubber particles Seasonal frozen regions

a b s t r a c t To improve the durability of tack coat applied to orthotropic steel bridge decks against freeze-thaw cycle in seasonally frozen regions, an epoxy asphalt (EA) tack coat modified by silane coupling agent surfacetreated rubber particles (ARP) is proposed. In comparison with epoxy asphalt and epoxy asphalt rubber (EAR), the performance of ARP modified epoxy asphalt (EAAR) and EAAR tack coat were evaluated by conducting an experimental program in the laboratory. The properties of studied tack coat binders were first evaluated by viscosity, direct tensile and bending beam rheometer tests. Furthermore, the steel-asphalt interface performance including pull-off, shear and freeze-thaw damage resistance were evaluated as well. Results show that the incorporation of ARP can improve the mechanical properties and freezethaw damage resistance of EAAR, but it had shown a negative effect on the allowable construction time. When EAAR tack coat was used, the low temperature pull-off and shear strength can be improved to approximately 1.2 times that of EA tack coat, and the average interface fracture energy of the EAAR tack coat was about twice higher than EA tack coat. Moreover, EAAR tack coat had shown higher freeze-thaw damage resistance than EA tack coat, regardless of the higher nominal seepage pressure ratio, higher shear strength ratio and lower freeze-thaw damage ratio at the same freeze-thaw cycle periods. All the above findings indicate that the EAAR is of great potential to be applied as tack coat for seasonally frozen orthotropic steel bridge decks. Ó 2020 Elsevier Ltd. All rights reserved.

1. Introduction Epoxy asphalt is implemented as wearing course on orthotropic steel deck bridges mainly because of its excellent durability, high fatigue and aging resistance [1,2]. In order to enhance the interfacial adhesive strength between the steel decks and asphalt pave⇑ Corresponding author at: Intelligent Transport System Research Center, Southeast University, No. 35 Jingxianghe Road, Nanjing 210096, China. E-mail addresses: [email protected] (Q. Huang), [email protected] (Z. Qian), [email protected] (L. Chen), [email protected] (X. Zhang), hujing@seu. edu.cn (J. Hu). https://doi.org/10.1016/j.conbuildmat.2019.117957 0950-0618/Ó 2020 Elsevier Ltd. All rights reserved.

ments, the epoxy asphalt is used as tack coat as well [3–5], an application which is of high importance particularly in seasonally frozen regions [6]. One of the most prominent actions of the environment in seasonal frozen regions is the recurrent freeze-thaw (FT) cycles, which is caused by high-frequency temperature/moisture fluctuations around 0 °C. Large numbers of studies have shown that when exposed to recurrent freeze-thaw cycles, moisture can easily intrude along with the pavement cracking and pavement interface, causing severe degradation of tack coat and subsequently leading to loss of cohesion strength and slippage failure [7–10]. This distress shortens the service life of asphalt pavement of orthotropic steel bridge deck, and increases the

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Q. Huang et al. / Construction and Building Materials 241 (2020) 117957

maintenance frequency and costs. Therefore, it is worthwhile to explore some approaches to improve the tack coat for better low-temperature deformation capability and recurrent freezethaw cycle damage resistance for the specified traffic and climate conditions in seasonally frozen regions. Extensive studies have shown that the crumb rubber is an excellent polymer-based modifier for asphalt binders since it can improve the fatigue cracking, rutting and low temperature cracking resistance of asphalt pavements [11–14]. These benefits make the using of crumb rubber in asphalt pavement very attractive in seasonally frozen regions. Additionally, considerable attention has already been paid to improving the crack resistance of epoxy asphalt (EA) by incorporating rubber particles of high-elasticity. Liu et al. investigated the application of elastic rubber in epoxy asphalt, and it was found that asphalt rubber can improve the elongation of the neat epoxy to a certain extent with a benefit of lower cost [15,16]. Qian et al. proposed that the rubber particles with the appropriate size and content can improve tensile strength and fracture elongation of EA, indicating that the addition of rubber particles can improve crack resistance of EAC at low temperatures [17]. Zhang et al. investigated the effect of rubber particles and polyester fiber on low temperature cracking resistance on EAC, and the test results showed that the flexibility and toughness of epoxy asphalt concrete can be improved significantly by incorporating rubber particles and polyester fiber [18]. The generation and development of the freeze-thaw cycle damage is quite a complicated dilemma which can lead to great loss of service life for asphalt pavement in seasonal frozen regions. Lots of studies have shown that adding water-stabilization modifiers is one of the most cost-effective techniques for alleviating freezethaw cycle damage [19,20]. Silane coupling agent (SCA), known as ‘‘molecular bridge” which can make two relatively inert materials cross-linked by winding up the covalent bond, has been proved to be a highly promising water-stabilization additive for asphalt pavement [21]. Zhang et al. determined that modifying the asphalt concrete mixes with silane coupling agents can improve the rutting resistance and moisture stability [22]. Min et al. developed a new silane coupling agent to enhance the moisture damage resistance of asphalt mixture by surface treating the basalt aggregates, and the results indicated that the new silane coupling agent had an apparent effect on improving the interfacial performance between basalt and asphalt [23]. Xie et al. suggested that the asphalt mixture with surface-treated fly ash by silane coupling agent had excellent moisture stability in terms of higher indirect tensile strength and tensile strength ratio during freeze-thaw process [24]. In summary, the silane coupling agent can be used as a water-stabilization additive for asphalt pavement in seasonal frozen regions, considering its potential advantage in the resistance to freeze-thaw cycle damage. Although previous researchers have paid lots of attentions to regular performances of EA and EA tack coat, few efforts have been devoted to improving the low-temperature cracking resistance and the F-T cycle damage resistance. In this paper, the objective is to find out an effective method to modify the EA tack coat, which can make it better-fitting for orthotropic steel bridge deck pavement in seasonal frozen regions.

2. Materials and methods 2.1. Materials 2.1.1. Asphalt binder Epoxy asphalt is a mixture of two phase chemical substances, in which the thermosetting epoxy is the continuous phase and asphalt is the disperse phase. A labprepared EA binder consisting of two components was applied as tack coat. In EA, component A is an epoxy resin (diglycidyl ether of bisphenol-A) and component B is an asphalt material containing the anhydride curing agent in base asphalt.

The formulations containing diglycidyl ether of bisphenol-A and certain anhydride curing agent are widely used for the warm-mix epoxy asphalt tack coat (WMEA) in China [25]. In this research, the weight ratio of epoxy resin, curing agent and base asphalt is fixed at 55:45:100. The fundamental properties of the asphalt binder were noted in Table 1. For the preparations of epoxy asphalt rubber (EAR) and epoxy asphalt rubber with SCA (EAAR), base asphalt in the component B were replaced by normal rubber particles modified asphalt (AR) and SAC surfacetreated rubber particles modified asphalt (AAR). Moreover, epoxy asphalt concrete (EAC) used in this research selected a commercial EA as binder with a content of 6.8% wt. 2.1.2. Rubber particles and silane coupling agent The rubber particles used in this research were commercial products supplied with different sizes, including 40, 80 and 120 mesh. Because of the great hydrophobicity and high reactivity with the epoxy monomers, an amino-silane coupling agent named (3-aminopropyl)triethoxysilane (APTES) was selected as the modifier to treat the surface of rubber particles, as shown in Fig. 1. Its properties are summarized in Table 2. To produce SCA surface-treated rubber particles (i.e., ARP), normal rubber particles were first immersed in a mixture of 20 wt% APTES, 40 wt% ethanol, and 40 wt% water for 48 h, then went on a freeze-drying process for 24 h. During the surface-treatment, the alkoxy –OC2H5 connected with –Si– in APTES formed – Si-OH by hydrolysis reaction, and –Si-OH continued to interact with the hydroxyl groups on the surface of rubber particles, stable bonds formed after hydrogen bonds were dehydrated by heat, then APTES fixed firmly on the surface, in this way the surface of normal rubber particles was fully modified [26]. To produce a homogenous mixture of the component B for EAAR, ARP and curing agent were introduced into the base asphalt by mixed with a high-shear emulsifier at 175 °C and 3000 rpm for 30 min. Subsequently, component A of epoxy resin was incorporated into component B and stirred at 120 °C for 60 s. Finally, the mixture of EAAR was poured into steel mold and went on a curing of 4 h at 120 °C and 5 days at 23 °C. For the production of EA and EAR, the mechanical blending and curing procedures of the asphalt binders were the same with EAAR. Fig. 2 is the schematic of a ring-open reaction between epoxy monomer and –NH2 on the surface of ARP. When introducing epoxy resin into component B for EAAR, epoxy monomers immediately reacted with epoxy cross-linkers (curing agent) to form a strong 3D net supporting structure in asphalt. At the same time, a ring-open reaction occurred through the interaction between epoxy monomers and –NH2 on the surface of ARP. In this way, the EAAR asphalt was produced. The ARP acted as a part of the curing system, not being physical embedded, which resulted in a more stable internal structure of epoxy asphalt rubber. 2.2. Methods 2.2.1. Asphalt binder testing In this research, comprehensive asphalt binder tests were first used to assess the mechanical properties of the EA, EAR, and EAAR asphalt binders. According to ASTM D4402-15 [27], the Brookfield viscosity test was conducted to determine the operability via the allowable construction time of viscosity from 0 to 1000 mPas at 120 °C. The direct tensile test was conducted to determine cracking resistance via the tensile strength and fracture elongation at 23 °C according to ASTM D638-14 [28]. The bending beam rheometer test was conducted to assess the low-temperature viscoelasticity via the creep stiffness (S) and rate of relaxation (m-value) at 12 °C according to ASTM D6648-08 [29]. 2.2.2. Composite slab fabrication The multilayer structure of steel deck (14-mm) – tack coat – EAC (40-mm) of composite slab was selected to simulate the orthotropic steel deck-asphalt pavement system, as shown in Fig. 3(a). The slabs were subjected to mechanical load as shown in Fig. 3(c), while Fig. 3(b) demonstrates the actual loading profile of an asphalt pavement on orthotropic steel deck. The steel deck used in this research was sandblasted and coated by epoxy zinc-rich primer with a thickness of 60 lm. The EA, EAR, and EARR were all prepared by introducing component A into component B and stirred at 120 °C for 1 min. After that, the prepared tack coat binder was coated homogeneously on the steel deck and followed by scattering 2.36– 4.75 mm gravels. Before fabricating steel deck – tack coat – EAC composite specimens, the steel deck with the tack coat was installed into the steel mold, then EAC was paved into the steel mold by static pressure load. Subsequently, the composite slab went on a curing of 4 h at 120 °C and 5 days at 23 °C to fully develop the

Table 1 Properties of the original EA binder for tack coat. Properties

For tack coat

Epoxy asphalt Mixing ratio of component A and B Allowable construction time/min Tensile strength@23 °C/MPa Facture elongation @23 °C/%

1:2.65 49 6.19 257

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Q. Huang et al. / Construction and Building Materials 241 (2020) 117957

pressure dropping (PDT) was recorded. The nominal seepage pressure (P0) was calculated using PDT and Ps, and used as the water tightness index. The computational formula is shown in Eq. (3).

P0 ¼ PS þ

PDT  DP t0

ð3Þ

where P0 is the nominal seepage pressure of tack coats (kPa); Ps is the specified test pressure (kPa); PDT is the time corresponding to the start of pressure dropping (min); t0 is the critical time for determination of water tightness (30 min); DP is the test pressure increment (50 kPa).

Molecular structure

Fig. 1. The picture of silane coupling agent (APTES) used in this study.

strengths of tack coat and EAC. As for the shear test, the original composite slabs were cut into smaller rectangular solids with the size of 40 mm in width, 40 mm in length and 54 mm in height, as shown in Fig. 4(d). As for pull-off test, the original composite slabs were further processed with several 50 mm-circular holes drilled, passing through the EAC till the steel plate surface, as shown in Fig. 4(e). 2.2.3. Steel-asphalt interface performance testing In comparison to EA and EAR tack coats, the performance of EAAR tack coat in the pavement structure were evaluated by conducting an experimental program in the laboratory. The steel-asphalt interface performance tests include the pull-off test, shear test and water tightness test. According to ASTM D7234-12 [30]. the pull-off test was conducted to assess the vertical adhesive property on the steelasphalt concrete cylindrical specimens (U50 mm  54 mm), and-18 °C, 0 °C, 25 °C and 60 °C were selected for test since they represent the low temperature, normal temperature and high temperature, at which orthotropic steel bridge deck pavement serves in the seasonally frozen regions. Under the guideline of JTG/T3364-02 [31,32]. The skew shear test was conducted to assess the shear resistance of the tack coat at the same test temperatures aforementioned, on the steel-asphalt concrete slab specimens (40 mm  40 mm  54 mm). It needs to be mentioned that the horizontal stress is about 100% of the vertical compressive stress caused by the vehicle load on pavement structure under emergency braking, as reported in previous studies [33,34], so the skew angle a was set at 45° in the shew shear test. Fig. 5 shows a typical applied load versus displacement curve at 23 °C. The energy dissipated (Gf) during the shearing failure process was calculated using Eqs. (1) and (2) [35].

Gf ¼

Wf bl Z

lf

Wf ¼

ð1Þ

F  dl

ð2Þ

0

where Gf is the interface fracture energy of tack coat (J/m2); b is the specimen width (m); l is the specimen length (m); Wf is the work done during the shear test, which is the area under the load-displacement curve (kNmm); lf is the load displacement at F = 0.1 kN post peak load (mm). According to EN 1928-B [36], the water tightness test was carried out to evaluate the impermeability of the tack coat using a water pressure apparatus. In this research, the water pressure apparatus consists of a steel cylinder to fill in water and compressed air, a barometer and two fixing plates. The pressure of compressed air in the cylinder is set from 100 kPa to 500 kPa since the hydrodynamic pressure on asphalt pavement caused by high-speed traffic loading is within this range, of which the impact on the pavement structure can’t be neglected [37]. PVC soft glass with tack coat binders coated on was first put in a rutting specimen fabrication mold (300  300  50 mm) before the compaction of epoxy asphalt mixture. After the PVC-tack coat-EAC composite slab finished a curing process of 4 h at 120 °C and 5 days at 23 °C, the PVC soft glass was stripped from the surface of the tack coat. Subsequently, the prepared composite slab was placed on the base plate of the apparatus, and the upper plate and the tack coat side were connected by a clamping bolt with a rubber ring sealing the gap. It was considered water of tack coat when no pressure attenuation occurred within 30 min [38]. Once the specified pressures (Ps) started to drop, the time corresponding to the start of

2.2.4. Long term freeze-thaw cycle test Moisture damage is major distress that orthotropic steel bridge deck pavement suffers. The action of moisture can lead to the disruption at the interface of the steel deck and asphalt pavement. Moreover, freeze-thaw (F-T) cycle damage in the built environment was considered as the most severe action of moisture damage on orthotropic steel bridge deck pavement. The long term F-T cycle test in this research was undertaken to assess the moisture damage resistance of EA, EAR and EAAR asphalt binders, as well as to evaluate the water tightness and shear resistance of tack coat interlayers. For asphalt binder evaluation, the freeze-thaw cycle simulation was finished before the direct tensile test and bending beam rheometer test, respectively. For tack coat interlayer evaluation, the testing procedures involve the long term freeze-thaw cycle simulation, nominal seepage pressure ratio (NSPR) measurement, shear strength ratio (SSR) measurement, and freeze-thaw degeneration ratio (DF-T) measurement. Based on AASHTO T283 testing procedure of freeze-thaw cycle simulation [39], the test specimens were first saturated under a vacuum of 97.3–98.7 kPa for 10 min. After that, the saturated test specimens were placed in a cryogenic box at 18 °C for 16 h. Subsequently, the frozen specimens were immersed in 60 °C water bath for 24 h. Step 2 and step 3 were repeated until the total desired number of F-T cycles were completed. The process of recurrent freeze-thaw cycles is shown in Fig. 6. After every three F-T cycles, shear strength and interface fracture energy (18 °C) of tack coats were recorded to calculate SSR and DF-T. Moreover, NSPR was defined as the stability of water tightness for tack coat when subject to F-T cycles, which was calculated using nominal seepage pressure values after every three F-T cycles. The calculation methods of NSPR, SSR, and DF-T are shown in Eqs. (4)–(6).

NSPR ¼

SSR ¼

Pn  100 P0

ð4Þ

rn  100 r0 

DFT ¼

1

Gfn Gf 0

ð5Þ   100

ð6Þ

where rn is the shear strength (18 °C) of tack coats subjected to n F-T cycles; r0 is the shear strength (18 °C) of tack coats without being subjected to freeze-thaw cycles; Gfn is the fracture energy (18 °C) of tack coats subjected to n F-T cycles; Gf0 is the fracture energy (18 °C) of tack coats without being subjected to freezethaw cycles; Pn is the nominal seepage pressure of tack coats subjected to n F-T cycles; P0 is the nominal seepage pressure of tack coats without being subjected to freeze-thaw cycles.

3. Results and discussion 3.1. Mechanical properties of tack coat binder The contents of normal rubber particles and SCA surface-treated rubber particles in AR and AAR were selected as 5, 10, 15 and 20 wt % respectively. The content of 0% represents the base asphalt for component B. Viscosity test, direct tensile test, low-temperature rheological test, and long term freeze-thaw cycle test were carried out to preliminarily assess the influences of RP and ARP on mechanical properties of the EAR and EAAR. 3.1.1. Viscosity test results The viscosity plays vital roles in coating the tack coat. Unlike other thermoplastic tack coat binders, epoxy asphalt binder is a

Table 2 Properties of silane coupling agent (APTES). Appearance

Purity %

Boiling point/°C

Flash point/°C

Density, 25 °C/gcm3

Transparent

98

217

104

0.946

4

Q. Huang et al. / Construction and Building Materials 241 (2020) 117957

H2N

C3H6

O

C2H5

Si

O

O

C2H5

C2H5

OH H2N

C3H6

Si

C3H6

Si

CH2

OH

H2C

OH

Heating C3H6

H2N

C3H6

Si

C3H6

CH

R

C4H8

NH2

H2O

Heating OH

O Si O

O

O Si O

CH2

O

O O

O

O

NH2

CH2 n

O O

Si

O

O Si O

C

C H

O

O O

HN

Si

OH OH

HO

O CH

C3H6

CH3

OH

OH R

OH

H2N

HO HO

OH

OH

H2N

Hydrolysis

C3H6

NH

CH2

CH

R

Fig. 2. Schematic of a ring-open reaction between epoxy monomer and –NH2 on the surface of ARP.

P

A

EAC (40mm)

Tack coat

Steel plate (14mm)

Epoxy zinc-rich Primer (60μm)

A

30cm 60cm

(a)

(b)

Underside

Broadside

6cm

6cm

10cm

4cm

10cm

10cm

4cm

0.9cm

30cm

4cm

1.4cm 1.4cm 3.6cm

4cm

5cm

Frontside

4cm

15cm

15cm

4cm

(c)

(d)

Fig. 3. Steel deck selection: (a) orthotropic steel bridge deck pavement structure; (b) location of steel-EAC composite slab; (c) steel deck size of composite slab; (c) steel deck of composite slab.

thermosetting material with starts to build-up its properties, such as viscosity and modulus, through an irreversible chemical reaction process named polymerization [40,41]. Take 80 mesh ARP as an example, it can be seen from Fig. 7 that the viscosity of EAAR in the initial stage increases slowly, and begins to increase rapidly when the viscosity reaches around 1000 mPas. Besides, the viscosity of EAAR increases with the increase of ARP content. However, if the viscosity is too high or the time of polymerization is too long, the EAAR will be too tough to be coated on orthotropic steel bridge

deck. Therefore, the allowable construction time of viscosity from 0 to 1000 mPas should be long enough, which is required to exceed 20 min [25]. In general, the ARP can increase the viscosity and shorten the allowable construction time for EAAR, which brings more challenges to spray EAAR tack coat. Hence the contents of ARP in EAAR should not be excessive for the sake of construction quality. As shown in Table 3, the increasing of allowable construction time of EAR and EAAR is coming along with the rubber particles

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Q. Huang et al. / Construction and Building Materials 241 (2020) 117957

(a)

(b)

(d)

(c)

(e)

Fig. 4. Specimens fabrication procedures: (a) steel mold; (b) steel deck with tack coat; (c) EAC compacted in mold; (d) specimens for shear test; (e) specimens for pull-off test.

14 12

Applied load/kN

10 0.1kN 8 6 4 2 0 0.0

0.2

0.4

0.6

0.8

1.0

1.2

Displacement/mm Fig. 5. Typical load-displacement curve.

size decline. It can be explained that the specific surface area increases with the decline of the RP and ARP size, and a larger specific surface area can lead to a shorter time for maximum swelling of RP and ARP in EAR and EAAR, leaving more time for depolymerisation and devulcanization of RP and ARP which can lower the viscosity [42]. Compared with EAR, EAAR with the same size and content of rubber particles has shorter allowable construction time. Moreover, with the decline of rubber particles size, the difference between allowable construction time of EAR and EAAR exhibits a distinct increase. This phenomenon denotes that APTES can accelerate the polymerization speed of EAAR, which is probable due to the ring-open reaction between epoxy monomer and –NH2 on the surface of ARP. It needs to note that EAR and EAAR with 80 mesh and 40 mesh rubber particles have shorter allowable construction time, but still longer than that of technical specification operational time [31], which provides enough time for workers to spray the EAR and EAAR tack coats on orthotropic steel bridge deck.

3.1.2. Direct tensile test results The tensile strength and fracture elongation of tack binder are important factors that affect the fracture resistance for the interface of the orthotropic steel bridge deck pavement. Take 80 mesh RP and 80 mesh ARP as examples, it can be figured from Fig. 8(a) that the introduction of RP and ARP increase the tensile strength of EAR and EAAR, and then decrease obviously when the content exceeds around 5%. The cause of tensile strength improvement lies in the swelling action of rubber particles and aromatic oil absorption of rubber particles in EAR and EAAR. However, once the content of RP or ARP exceed 5%, a tremendous difference in the viscosity between AR or AAR and epoxy matrix comes into being, a poor distribution of co-continuous phase-separated structure of AR or AAR is frozen by the gelation of the epoxy matrix, thereby leading to a dramatic decrease of the tensile strength, which is in consistent with the previous study [15]. Furthermore, the comparison between EAR and EAAR in tensile strength reveals that EAAR has a better capability of withstanding tensile force, which can be attributed to the stronger bond between the epoxy monomer and the –NH2 on the surface of the ARP. In addition, it can be concluded from Fig. 8(b) that for EAR and EAAR, the fracture elongation increases with the introduction of rubber particles at the initial stage, and then begins to dramatically attenuate when the contents of RP and ARP exceed about 5%. This is mainly because of the poor distribution of co-continuous phaseseparated structure mentioned before. Compared with EAR, the crosslink density of EAAR was increased by the interaction between ARP and the epoxy monomer, which leads to a more brittle characteristic. As a result, the fracture elongation of EAAR are little lower than that of EAR at the same rubber particles size and content. As shown in Table 4, the tensile strength of EAR and EAAR all decrease with the decline of rubber particles size. The mechanism behind this can be explained that the specific surface area increases with the decline of the RP and ARP size, and a larger specific surface area can bring about a more intense depolymerisation and devulcanization, which will offset the positive effect of swelling action and aromatic oil absorption of rubber particles on the tensile strength [42]. In another hand, the fracture elongation

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Q. Huang et al. / Construction and Building Materials 241 (2020) 117957

Sample Preparation

F-T Cycle 1

F-T Cycle N

F-T Cycle 2

Temperature /

Curing@ 120 ,4h

Curing@ 23 ,5d

Soaking in Water Bath@ Vacuum 60 ,24h saturated@ 23 ,10min

Freezing in Air Bath@ -18 ,16h

Soaking in Water Bath@ 60 ,24h

Soaking in Water Bath@ 60 ,24h Cooling@ 23 ,2h

Freezing in Air Bath@ -18 ,16h

Freezing in Air Bath@ -18 ,16h

Time Fig. 6. Schematic representation of long-term freeze-thaw cycle simulation.

7.2

12000

EAR

EAAR

0% 10000 8000

10%

6000

15%

Tensile strength/MPa

Viscosity/mPa·s

5%

20% 4000

1000mPa·s

6.6

6

5.4

2000 4.8

0 0

15

30

45

60

75

0

90

5

10

15

20

Content of rubber particle/%

t/min

(a)

Fig. 7. Viscosity time curves @ 120 °C of the EAAR when ARP is 80 mesh.

400

EAR

EAAR

Table 3 The allowable construction time of EAR and EAAR. Size/mesh

Content/%

EAR

EAAR

–

0

47

47

40(425 lm)

5 10 15 20

42 36 32 28

40 34 31 27

80 (178 lm)

5 10 15 20

44 38 33 30

42 35 33 28

5 10 15 20

45 40 36 33

43 38 34 30

120(125 lm)

The Allow Construction Time/min

Fracture elongation/%

340

280

220

160

100

0

5

10

15

20

Content of rubber particle/%

(b) Fig. 8. Direct tensile test results of EAR and EAAR when normal rubber particles and SCA surface-treated rubber particles are 80 mesh: (a) tensile strength, (b) fracture elongation.

7

Q. Huang et al. / Construction and Building Materials 241 (2020) 117957 Table 4 Direct tensile test results of EAR and EAAR. Size/mesh

Content/%

Tensile Strength/MPa EAR

EAAR

EAR

EAAR

–

0

6.13

6.13

257

257

40 (425 lm)

5 10 15 20

6.88 6.47 5.58 5.14

7.03 6.67 6.11 5.66

342 303 208 172

319 266 197 132

80 (178 lm)

5 10 15 20

6.79 6.27 5.35 4.89

6.98 6.58 5.91 5.32

358 325 233 178

332 274 218 137

120(125 lm)

5 10 15 20

6.66 6.13 5.21 4.27

6.75 6.31 5.76 5.15

366 342 241 194

343 289 227 151

of EAR and EAAR obviously increase with the decline of rubber particles size. The reason of this could be the increasing of light and small molecule contents caused by the more intense depolymerisation and devulcanization action of finer RP and ARP, which can slightly mitigate the brittle crack tendency of EAR and EAAR. Hence the size of RP and ARP in EAR and EAAR should neither be too big nor too small. Based on all the test results as discussed above, the EAR with 5% RP (80 mesh) and EAAR with 5% ARP (80 mesh) were used in the further investigations. 3.1.3. Long term freeze-thaw cycle test results The changes in the low-temperature rheological and mechanical properties of tack binders when subjected to recurrent freezethaw cycles are summarized in Table 5. As for low-temperature rheological property of original EA, EAR and EAAR, using RP and ARP can remarkably decrease the creep stiffness S and increase the m-value, which indicates EAR and EAAR can withstand larger deformations to defer crack propagation from inside. After 18 freeze-thaw cycles, EA, EAR and EAAR tack coats all suffer a rheological properties degradation caused by water aging. Based on Fick’s law [19], the concentration gradients of the surface chemical substances and internal chemical substances in the contact between the tack coat binder and water can constrain the moisture into the tack coat binder. The dissolution of moisture causes the component of the asphalt materials in tack coat binder to change, which makes tack coat binder hardened after a number of freeze-thaw cycles [20]. Among all the tack coat binders, EAAR has the least increment (15.6%) in creep stiffness S and EAR has the second (19.9%). As for the reduction in m-value, EAAR has the least (8.9%) and EAR has the second (24.5%) as well. It can be concluded that APTES on ARP can effectively improve the EAAR’s resistance to the F-T cycles damage, which is probably because of the high hydrophobicity to resist the moisture entering tack coat binder. Also in Table 5, it can be deduced from the changes in tensile strength and fracture elongation that EAAR has the most stable performance in fracture resistance when exposed to freeze-thaw cycles, the reason of which could be the same in lowtemperature rheological property.

Fracture Elongation/%

3.2. Steel-Asphalt interface performance of tack coat 3.2.1. Pull-off test results As an interlayer between orthotropic steel bridge deck and asphalt pavement, tack coat should have a strong adhesion to prevent interface pull-off failure [43]. It can be found from Fig. 9(a) that, with the increasing of tack coat application rates, the pull-off strength (23 °C) of tack coats all increase initially and then decrease. When the application rate increases from 0.3 kg/m2 to 0.7 kg/m2, the pull-off strength of EA, EAR and EAAR tack coats increase by 39.5%, 41.9% and 36.9%, respectively. This phenomenon can be explained that higher application rate of tack coat can provide a more sufficient adhesion due to a better contact in the steel-asphalt interfacial gap [44]. Once exceeding the optimal application rate, an oil-rich sliding layer will come into being, which leads to the decline of pull-off strength. As a result, 0.7 kg/m2 could be regarded as the optimal application rate, and the order of the pull-off strength (23 °C) for the three tack coats is EAAR > EAR > EA. The application rate of 0.7 kg/m2 was used for all tack coats in the further investigations. Besides, it can be seen from Fig. 9(b) that with the rise of test temperature, the pull-off strength of tack coats all decrease, and the decline amplitude of strength for tack coats are especially great at the temperature from 0 °C to 25 °C. This is mainly attributed to the viscoelastic character and temperature sensitivity of the asphalt materials in tack coats. Moreover, since the crosslink between ARP and the epoxy monomer can help to withstand greater force, the pull-off strength of EAAR tack coat are 5.49%– 6.34% and 14.82%–25.0% higher than EAR tack coat and EA tack coat at the varying test temperatures. Such a result indicates that the adhesion performance of EAAR tack coat is best preserved within the seasonal frozen reigns temperature range. 3.2.2. Shear test results The shear test of tack coat was conducted at 18 °C, 0 °C, 25 °C and 60 °C respectively. It can be found from Fig. 10(a) that the shear strength of tack coat is sensitive to the test temperature, and all increase with the decreasing of test temperature. The largest increasing amplitude of strength for tack coats all appear at

Table 5 Properties of EA, EAR and EAAR before and after long term F-T cycles. Properties

Creep stiffness S/MPa m-value Tensile strength/MPa Fracture elongation/%

Temperature

12 °C 12 °C 23 °C 23 °C

Criteria

<300 >0.3 6.0 190

Before F-T cycles

After 18 F-T cycles

EA

EAR

EAAR

EA

EAR

EAAR

247.6 0.333 6.13 257

225.1 0.387 6.79 bes

230.4 0.371 6.98 332

319.4 0.213 4.48 131

270.1 0.292 5.69 236

266.3 0.301 5.85 242

8

Q. Huang et al. / Construction and Building Materials 241 (2020) 117957

4

9 7.5

Shear strength/MPa

Pull-off strength/MPa

3.5

3

2.5

EA EAR

2

EAAR

0.5

0.7

EAR

6

EAAR

4.5 3 1.5

1.5 0.3

EA

0.9

0 -20

1.1

0

Application rate/kg·m-2

20

60

Temperature/°C

(a)

(a) 20

8.5

EA EAAR EAR

16

7

EA EAR

5.5

Load/kN

Pull-off strength/MPa

40

EAAR

4

8

4

2.5

1 -20

12

0 0

20

40

60

Temperature/°C

(b) Fig. 9. Pull-off test results of EA tack coat, EAR tack coat and EAAR tack coat: (a) strength vs application rate, (b) strength vs temperature.

the temperature from 25 °C to 0 °C, which is the same with the pull-off test results. In addition, with the decline of temperature, the gaps between shear strength of EAAR tack coat and the other two tack coats increase obviously. The shear strength value of EAAR tack coat is 21.9% and 6.24% higher than that of EA tack coat and EAR tack coat at 18 °C, respectively. To further analyze the anti-shearing performances at low temperature, the average interface fracture energies (18 °C) of the EA, EAR and EAAR tack coats are used, which are calculated as 1962 J/ m2, 4366 J/m2, and 4250 J/m2. It can be found that EAR tack coat and EAAR tack coat both have superior low-temperature shearing resistance to the EA tack coat, because EAR tack coat and EAAR tack coat have about twice higher average fracture energy values than the EA tack coat. The Gf depends on not only the peak load but also the load displacement. A higher peak load and a greater displacement will result in a higher interface fracture energy. As shown in Table 6, the average peak loads of the EA tack coat, EAR tack coat, and EAAR tack coat are 14.208 kN, 16.312 kN, and 17.392 kN, respectively. Compared with the EA tack coat, the EAR tack coat and EAAR tack coat have higher average peak loads. Moreover, both EAR tack coat

0

0.3

0.6

0.9

1.2

1.5

Displacement/mm

(b) Fig. 10. Shear test results of EA tack coat, EAR tack coat and EAAR tack coat: (a) Shear strength vs temperature, (b) Load vs displacement (18 °C).

and EAAR tack coat have much greater load displacements than the EA tack coat. The average displacements at peak load of EA tack coat, the EAR tack coat and EAAR tack coat are 0.44 mm, 0.98 mm, and 0.85 mm, respectively. In addition, it can be found that the EAR tack coat and EAAR tack coat have smoother curves after the peak load, which indicates the post-shearing behavior was effectively improved. The smoother curves were likely attributed to the high-elasticity of the rubber particles. In brief, this result means that using high-elastic RP and ARP can effectively reduce the risk of brittle shearing failure which EA tack coat suffers at low temperature.

3.2.3. Water tightness test results Table 7 summarizes the water tightness test derived results of the three tack coats. It can be found that the tack coats all show excellent water tightness performance when subjected to the water pressure below 300 kPa. However, once the water pressure is raised from 300 kPa to 350 kPa, the seepage phenomenon occurs after 15 min and 28 min for EA tack coat and EAR tack coat respectively, while the EAAR tack coat remains impermeable. The water tightness state of EAAR tack coat is stable until the water pressure

9

Q. Huang et al. / Construction and Building Materials 241 (2020) 117957 Table 6 Average interface fracture energies of EA tack coat, EAR tack coat, and EAAR tack coat. Tack coat Materials

Test Temperature

Average Interface Facture Energy (J/m2)

Average Peak Load (kN)

Average Displacement at Peak Load (mm)

EA EAR EAAR

18 °C 18 °C 18 °C

1962 4366 4250

14.208 16.312 17.392

0.44 0.98 0.85

100

Table 7 Water tightness test results of EA tack coat, EAR tack coat, and EAAR tack coat. Specified Test Pressure/kPa

Test Phenomenon PDT/min

Nominal Seepage Pressure/kPa

EA

200 250 300 350

No pressure drop occurs within 30 min

– – – 375.0

200 250 300 350

No pressure drop occurs within 30 min

– –

Pressure drop after 28 min

396.7

250 300 350 400

No pressure drop occurs within 30 min

– – – 410.0

EAR

EAAR

Pressure drop after 15 min

Pressure drop after 6 min

85

NSPR%

Tack Coat Materials

70

EA

55

EAR EAAR 40

0

3

6

9

12

15

18

Number of F-T cycles Fig. 11. Nominal seepage pressure ratio of three tack coats under the F-T cycles.

3.2.4. Long term freeze-thaw cycle test results The changes in nominal seepage pressure ratio (NSPR) after freeze-thaw cycles were determined for all the tack coats and plotted in Fig. 11. In this research, the number of F-T cycles for original tack coat is regarded as zero. As shown in Fig. 11, the NSPRs all decrease with the progress of F-T cycles, which means that the freeze-thaw cycles have a negative impact on the water tightness of tack coats. This can be explained that the frost heave action and asphalt-scattered gravel interface damage occur within the internal structure of the interlayer during the F-T cycles, consequently leading to the recession of nominal seepage pressure of tack coats. Compared to EA and EAR tack coats, EAAR tack coat have the higher NSPR and lower attenuation rates when exposed to the same F-T cycles, indicating a greater resistance to freeze-thaw cycle damage. It is mainly because the high elastic recovery of the rubber particles is benefit for the self-healing action of microscopic cracks in the heated thawing process. Additionally, due to the high hydrophobicity of the APTES, the difference in NSPR values between the EAR tack coat and EAAR tack coat gets larger, which means that the APTES also can effectively relieve the freeze-thaw cycle damage to the water tightness of EAAR tack coat. The mechanical properties of EA tack coat, EAR tack coat, and EAAR tack coat were evaluated for every three F-T cycles by the

shew shear test. The shear strength ratio (SSR) and freeze-thaw damage ratio (DF-T) values of the three tack coats were determined and plotted in Figs. 12 and 13, respectively. As shown in Figs. 12 and 13, all tack coats suffer a degradation of SSR and a rise of DF-T when subjected to recurrent F-T cycles. Specifically, it can be seen from Fig. 12 that after 18 F-T cycles, the average attenuating rate of SSR for EA tack coat is 4.33% per F-T cycle, approximately 2.16 and 2.60 times that of EAR tack coat and EAAR tack coat, respectively. Furthermore, the attenuating rates of SSR for EAAR tack coat change least in the process of F-T cycles. This is probably because the aforementioned high hydrophobicity of APTES and the strong recovery caused by rubber particles of high elasticity, both of which can effectively relieve the freeze-thaw cycle damage.

100

EA EAR 85

SSR/%

increases to 400 kPa. Based on the PDT values in the test, the nominal seepage pressure value of EAAR tack coat is calculated as 410 kPa, which is 13.3 kPa and 35 kPa higher than that of EAR tack coat and EA tack coat. This indicates that using EAAR to replace EA or EAR in tack coat can withstand a much higher water pressure to prevent water seepage in the interface of pavement structure. It is likely because the higher viscosity and greater crosslink density of EAAR can decline the penetration speed of high-pressure water. The order of water tightness for the three tack coats is EAAR > EAR > EA. As a result, EAR and EAAR tack coats are more recommendable when considering the water tightness performance of the orthotropic steel bridge deck pavement.

EAAR

70

55

40

0

3

6

9

12

15

Number of F-T cycles Fig. 12. Shear strength ratio of three tack coats under the F-T cycles.

18

10

Q. Huang et al. / Construction and Building Materials 241 (2020) 117957

respect to the fracture energy. EAAR tack coat and EAR tack coat have at least twice higher average fracture energy values than the EA tack coat. Besides, EAAR tack coat has a great performance of water tightness. (4) Compared to EA tack coat and EAR asphalt tack, EAAR tack coat have higher NSPRs and lower attenuating rates when exposed to the same number of freeze-thaw cycles. Additionally, during 3–9 cycles of freeze-thaw, the attenuating rates of NSPR for EAAR tack coat are marginally declining. (5) Under recurrent freeze-thaw cycles, the SSR value of EAAR tack coat is higher than that of EA tack coat and EAR tack coat, and its average attenuating rate is 1.67% per F-T cycle. Moreover, the DF-T value of EAAR tack coat increases slowly and experience an evident decline in the increasing rate of DF-T value in the process of 3–9 cycles of freeze-thaw.

50

EA EAR

40

DF-T /%

EAAR 30

20

10

0 0

3

6

9

12

15

18

Number of F-T cycles Fig. 13. Freeze-thaw damage ratio of three tack coats under the F-T cycles.

Additionally, it can be found from Fig. 13 that the freeze-thaw damage of EA tack coat increase sharply in the development of the F-T cycles, whereas the DF-T values of EAR tack coat and EAAR tack coat increase slowly, and both of the increasing rates experience an obvious decline in the process of 3 F-T cycles to 9 F-T cycles. This pheromone means that the EAR tack coat and EAAR tack coat have superior resistance to F-T damage compared to EA tack coat. Moreover, compared with EAR tack coat, EAAR tack coat has lower DF-T value, which shows that the tack coat containing the ARP has a more brilliant performance on the freeze-thaw cycle damage resistance due to the high hydrophobicity of APTES aforementioned. 4. Conclusions This paper assessed the effect of silane coupling agent surfacetreated rubber particles on epoxy asphalt rubber, and investigated the feasibility of applying epoxy asphalt rubber with silane coupling agent as tack coat for seasonally frozen orthotropic steel bridge decks. Comprehensive laboratory tests were conducted to evaluate the engineering performances of EAAR and EAAR tack coat. The following conclusions can be drawn according to the laboratory testing results: (1) The silane coupling agent surface-treated rubber particles (ARP) can increase the viscosity of EAAR and shorten the allowable construction time of EAAR tack coat, and can bring more challenges to the spraying of EAAR tack coat. The allowable construction time of EAAR is shorter than that of EA and EAR but still meet the performance requirement of 20 min. Compared to EA and EAR, the tensile strength and fracture elongation of EAAR are effectively improved by incorporating ARP with appropriate size and content. (2) Both the low-temperature rheological and mechanical properties of EAAR are preserved better than that of EA and EAR when subjected to freeze-thaw cycles conditioning, revealing that the ARP can be used as a modifier to effectively improve the resistance to the freeze-thaw cycle damage of EAAR due to the high hydrophobicity of APTES. (3) When EAAR is used as the asphalt binder for tack coat, the pull-off strength is 14.82%–25.0% and 5.49%–6.34% higher than that of EA and EAR respectively within the seasonal frozen reigns temperature range. Moreover, EAAR tack coat and EAR tack coat possess superior low-temperature shearing failure resistance when compared to the EA tack coat with

Without considering the shorter allowable construction time, the test results show the superior properties of EAAR and EAAR tack coat, especially in terms of the resistance to freeze-thaw cycle damage. Therefore, it is promising to use EAAR tack coat to resist the high-frequency temperature/moisture fluctuation in seasonal frozen regions while preserving the other interlaminar performances. Further research will be conducted with field testing of such a tack coat to verify the findings obtained from the laboratory study. CRediT authorship contribution statement Qibo Huang: Methodology, Formal analysis, Investigation, Writing - original draft, Writing - review & editing. Zhendong Qian: Conceptualization, Methodology. Leilei Chen: Methodology, Formal analysis, Writing - review & editing. Meng Zhang: Data curation, Writing - original draft, Writing - review & editing. Xiaorui Zhang: Data curation, Writing - review & editing. Jian Sun: Data curation, Writing - review & editing. Jing Hu: Writing - review & editing. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgment This research was funded by the National Natural Science Foundation of China (NOs. 51678146 and 51708113). The authors are grateful for their financial support. References [1] Q. Lu, J. Bors, Alternate uses of epoxy asphalt on bridge decks and roadways, Constr. Build. Mater. 78 (2015) 18–25, https://doi.org/10.1016/ j.conbuildmat.2014.12.125. [2] P. Apostolidis, X. Liu, S. Erkens, et al., Evaluation of epoxy modification in bitumen, Constr. Build. Mater. 208 (2019) 361–368, https://doi.org/10.1016/ j.conbuildmat.2019.03.013. [3] X. Jia, B. Huang, B.F. Bowers, et al., Investigation of tack coat failure in orthotropic steel bridge deck overlay survey, analysis, and evaluation, Transp. Res. Rec. 2444 (2014) 28–37, https://doi.org/10.3141/2444-04. [4] E. Bocci, F. Canestrari, Analysis of structural compatibility at interface between asphalt concrete pavements and orthotropic steel deck surfaces, Transp. Res. Rec. 2293 (2012) 1–7, https://doi.org/10.3141/2293-01. [5] C. Chen, W.O. Eisenhut, K. Lau, et al., Performance characteristics of epoxy asphalt paving material for thin orthotropic steel plate decks, Int. J. Pavement Eng. (2018) 1–11, https://doi.org/10.1080/10298436.2018.1481961. [6] M. Zhang, Z. Qian, Q. Huang, Test and evaluation for effects of freeze-thaw cycles on fracture performance of epoxy asphalt concrete composite structure, J. Test. Eval. 47 (1) (2019) 556–572, https://doi.org/10.1520/jte20170093. [7] T.O. Medani, X. Liu, M. Huurman, et al., Characterization of surfacing materials for orthotropic steel deck bridges. Part 1: experimental work, Int. J. Pavement Eng. 11 (3) (2010) 237–253, https://doi.org/10.1080/10298430902943033.

Q. Huang et al. / Construction and Building Materials 241 (2020) 117957 [8] X. Liu, T.O. Medani, A. Scarpas, et al., Characterization of surfacing materials for orthotropic steel deck bridges. Part 2: numerical work, Int. J. Pavement Eng. 11 (3) (2010) 255–265, https://doi.org/10.1080/10298430902859346. [9] W. Si, B. Ma, N. Li, et al., Reliability-based assessment of deteriorating performance to asphalt pavement under freeze-thaw cycles in cold regions, Constr. Build. Mater. 68 (2014) 572–579, https://doi.org/10.1016/ j.conbuildmat.2014.07.004. [10] J. Jiang, F. Ni, Q. Dong, et al., Investigation of the internal structure change of two-layer asphalt mixtures during the wheel tracking test based on 2D image analysis, Constr. Build. Mater. 209 (2019) 66–76, https://doi.org/10.1016/ j.conbuildmat.2019.02.156. [11] M. Heitzman, Design and construction of asphalt paving materials with crumb rubber modifier, Transp. Res. Rec. (1339) (1992). [12] T. Ma, H. Wang, L. He, et al., Property characterization of asphalt binders and mixtures modified by different crumb rubbers, J. Mater. Civ. Eng. 29 (7) (2017), https://doi.org/10.1061/(asce)mt.1943-5533.0001890. [13] X. Ding, L. Chen, T. Ma, et al., Laboratory investigation of the recycled asphalt concrete with stable crumb rubber asphalt binder, Constr. Build. Mater. 203 (2019) 552–557, https://doi.org/10.1016/j.conbuildmat.2019.01.114. [14] H. Wang, X. Liu, P. Apostolidis, et al., Review of warm mix rubberized asphalt concrete: towards a sustainable paving technology, J. Clean. Prod. 77 (2018) 302–314, https://doi.org/10.1016/j.jclepro.2017.12.245. [15] Y. Liu, Z. Xi, J. Cai, et al., Laboratory investigation of the properties of epoxy asphalt rubber (EAR), Mater. Struct. 50 (5) (2017), https://doi.org/10.1617/ s11527-017-1089-4. [16] J. Gong, Y. Liu, Q. Wang, et al., Performance evaluation of warm mix asphalt additive modified epoxy asphalt rubbers, Constr. Build. Mater. 204 (2019) 288–295, https://doi.org/10.1016/j.conbuildmat.2019.01.197. [17] Z. Qian, R. Wang, T. Chen, Performance of epoxy asphalt and its mixture under different rubber powder dosages, J. Build. Mater. 17 (2) (2014) 331–335, https://doi.org/10.3969/j.issn.1007-9629.2014.02.027. [18] Z. Zhang, K. Zhang, Z. Li, et al., Technique research on flexibility and toughness modification for epoxy asphalt concrete, J. Chang’an Univ. (Nat. Sci. Ed.) 35 (1) (2015) 1–7, https://doi.org/10.19721/j.cnki.1671-8879.2015.01.001. [19] W. Guo, X. Guo, W. Chen, et al., Laboratory assessment of deteriorating performance of nano hydrophobic silane silica modified asphalt in springthaw season, Appl. Sci. Basel. 9 (11) (2019), https://doi.org/10.3390/ app9112305. [20] T. Nian, P. Li, X. Wei, et al., The effect of freeze-thaw cycles on durability properties of SBS-modified bitumen, Constr. Build. Mater. 187 (2018) 77–88, https://doi.org/10.1016/j.conbuildmat.2018.07.171. [21] H. Chen, B. Tang, Surface modification of fire-retardant asphalt with silane coupling agent, J. Wuhan Univ. Tech.-Mater. Sci. Ed. 27 (2) (2012) 310–315, https://doi.org/10.1007/s11595-012-0458-7. [22] A. Zhang, Y. Wang, C. Zhuang, Discussion the effect on improving granite bituminous mixture performance by adding coupling agent, in: W.J. Yang, Q.S. Li (Eds.), Progress in Industrial and Civil Engineering, Pts. 1-52012, pp. 4115– 4118. https://doi.org/10.4028/www.scientific.net/AMM.204-208.4115. [23] Y. Min, Y. Fang, X. Huang, et al., Surface modification of basalt with silane coupling agent on asphalt mixture moisture damage, Appl. Surf. Sci. 346 (2015) 497–502, https://doi.org/10.1016/j.apsusc.2015.04.002. [24] J. Xie, S. Wu, L. Pang, et al., Influence of surface treated fly ash with coupling agent on asphalt mixture moisture damage, Constr. Build. Mater. 30 (2012) 340–346, https://doi.org/10.1016/j.conbuildmat.2011.11.022.

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[25] W. Huang, Theory and Method of Deck Paving Design for Long-span Bridges, China Construction Industrial Press, Beijing, 2006. [26] W. Huang, Z. Qian, T. Chen, Preparation method of epoxy asphalt modified by rubber powder, China Patent No. CN102796387A. [27] ASTM D4402-15, Standard Test Method for Viscosity Determination of Asphalt at Elevated Temperatures Using a Rotational Viscometer, 2012. [28] ASTM D638-14, Standard Test Method for Tensile Properties of Plastics, 2015. [29] ASTM D6648-08, Standard Test Method for Determining the Flexural Creep Stiffness of Asphalt Binder Using the Bending Beam Rheometer, 2008. [30] ASTM D7234-12, Standard Test Method for Pull-off Adhesion Strength of Coatings on Concrete Using Portable Pull-off Adhesion Testers, 2012. [31] Ministry of Transport of P.R. China, JTG/T3364-02, Specifications for Design and Construction of Pavement on Highway Steel Deck Bridge, 2019. [32] BSI EN 12697-48, Bituminous Mixtures. Test Methods for Hot Mix Asphalt. Part 48. Interlayer Bonding, 2014. [33] Y. Liu, J. Wu, J. Chen, Mechanical properties of a waterproofing adhesive layer used on concrete bridges under heavy traffic and temperature loading, Int. J. Adhes. Adhes. 48 (2014) 102–109, https://doi.org/10.1016/j. ijadhadh.2013.09.015. [34] X. Gu, W. Wang, Shear property demands of binding layer on concrete bridge pavement and simplified calculation, J. Tr. Transp. Eng. 2 (10) (2010) 20–25, https://doi.org/10.19818/j.cnki.1671-1637.2010.02.004. [35] V.V. Kumar, S. Saride, Evaluation of cracking resistance potential of geosynthetic reinforced asphalt overlays using direct tensile strength test, Constr. Build. Mater. 162 (2018) 37–47, https://doi.org/10.1016/ j.conbuildmat.2017.11.158. [36] BSI EN 1928-B, Flexible Sheets for Waterproofing Bitumen, Plastic and Rubber Sheets for Roof Waterproofing Determination of Water Tightness, 2000. [37] Q. Dong, Y. Li, X. Shi, et al., Calculation and analysis of hydrodynamic pressure on road surface, J. Chang’an Univ. (Nat. Sci. Ed.) 33 (5) (2013) 17–22, https:// doi.org/10.19721/j.cnki.1671-8879.2013.05.004. [38] F. Mazzotta, C. Lantieri, V. Vignali, et al., Performance evaluation of recycled rubber waterproofing bituminous membranes for concrete bridge decks and other surfaces, Constr. Build. Mater. 136 (2017) 524–532, https://doi.org/ 10.1016/j.conbuildmat.2017.01.058. [39] AASHTO T283, Standard Method of Test for Resistance of Compacted Asphalt Mixtures to Moisture-induced Damage, 2014. [40] P. Apostolidis, X. Liu, C. Kasbergen, et al., Chemo-rheological study of hardening of epoxy modified bituminous binders with the finite element method, Transp. Res. Rec. 2672 (28) (2018) 190–199, https://doi.org/10.1177/ 0361198118781377. [41] P. Apostolidis, X. Liu, M. van de Ven, et al., Kinetic viscoelasticity of crosslinking epoxy asphalt, Transp. Res. Rec. 2673 (3) (2019) 551–560, https://doi.org/10.1177/0361198119835530. [42] J. Shen, S. Amirkhanian, F. Xiao, et al., Surface area of crumb rubber modifier and its influence on high-temperature viscosity of CRM binders, Int. J. Pavement Eng. 10 (5) (2009) 375–381, https://doi.org/10.1080/ 10298430802342757. [43] M. Liu, S. Han, J. Pan, et al., Study on cohesion performance of waterborne epoxy resin emulsified asphalt as interlayer materials, Constr. Build. Mater. 177 (2018) 72–82, https://doi.org/10.1016/j.conbuildmat.2018.05.043. [44] X. Liu, A. Scarpas, J. Li, et al., Test method to assess bonding characteristics of membrane layers in wearing course on orthotropic steel bridge decks, Transp. Res Rec. 2360 (2013) 77–83, https://doi.org/10.3141/2360-10.