Research Progress of Epoxy Asphalt Material for Roads

Asphalt is a semi-solid or solid mixture formed by hydrocarbons and non-metallic elements.It is widely applied in the fields of building waterproofing and road paving.Asphalt is a low noise,durable,and renewable pavement material.However,asphalt materials have some shortcomings such as liquefying at high temperatures and brittleness at low temperatures,which are less adaptable to different environments.Therefore,people have gradually shifted their focus to asphalt modification.This paper presents an in-depth analysis and research on the composition,structure,and performance of epoxy asphalt materials for roads,so that this material can be widely used.

Preparation and characterization of epoxy asphalt binder for pavement of steel deck bridge

A kind of thermosetting asphalt binder designated as epoxy asphalt, which is composed of two components： maleated asphalt with curing agents and accelerant of epoxy resin and epoxy resin, was prepared. Its paving feasibility and concrete performances were investigated using Brookfield viscosimeter, direct tensile test （DTT）, Marshall testing and the MTS 810 hydraulic servos-system, respectively. Although only 50% to 60% of added maleic anhydride （MAH） reacted with the base asphalt irreversibly （probably by Diels-Alder mechanism）, the curing rate, rupture elongation and tensile strength of maleated epoxy asphalt were enhanced more evidently than those of unmaleated epoxy asphalt. As a result, an epoxy asphalt made from 4% MAH modified asphalt and other curing agents was featured to have an average rupture elongation of 281.9%, an average tensile strength of 2. 63 MPa, and the Marshall stability of its cured concrete reached 37. 0 kN, while that of uncured concrete was 10. 2 kN and the combined beam of fatigue test was still found to behave well after 12 × 10^6 cycles load.

Interfacial behaviors of epoxy asphalt surfacing on steel decks

A model for predicting the interface behavior of epoxy asphalt and steel composite beam under negative bending is developed incorporating partial interaction theory. Interfacial slips between the steel deck and the epoxy asphalt surfacing are included in the model with a new parameter of membrane stiffness. A series of analytical equations based on this model are derived to calculate slip and strain at the interface. Also, a numerical procedure for calculating the load responses of simply supported composite beams with concentrated force at the mid-span is established and verified with two samples. Characters of slip and strain at the interface, sensitivities of tensile stress and interface shear stress with material parameters are studied. It can be concluded that interfacial effects decrease the bending stiffness of the composite; hard and stiff bonding material is better for asphalt surfacing layer working at normal to low temperatures, and the damage of the asphalt surfacing layer will be accelerated with the damage accumulation of the bonding coat.

Construction controlling and strength increasing characteristics of locally developed epoxy asphalt mixture

The construction controlling elements,including construction performance at low ambient temperatures,reserved time ranges,and the strength increasing rule,for locally developed epoxy asphalt mixture（LDEAM） are studied through laboratory tests.Air void and Marshall stability are chosen as the performance measures for evaluating the construction quality.The wheel rolling test is used to simulate the actual construction situations,while the Marshall test and the Brookfield viscosity test are adopted to study the strength increasing rule.The experimental results reveal that the LDEAM can be constructed under a low ambient temperature condition of 10℃,and its longest reserved time is 70 min at a reserved temperature of 120℃.Test also shows that the strength of the LDEAM increases with time and temperature before cured.Finally,the theoretical reason for the strength increasing rule is analyzed on the basis of the organic chemistry theory.

Design and evaluation of epoxy asphalt geogrid stress- absorbing layer

In order to delay or eliminate the occurrence and expansion of the reflective cracking in the asphalt concrete overlay on old cement concrete pavement, an epoxy asphalt geogrid stress-absorbing layer（ EAGSAL） was designed. The EAGSAL consists of epoxy asphalt and fiberglass geogrid. The pull-out test, skewshearing test, bending beam test and fatigue test were conducted to evaluate the performance of the EAGSAL and a traditional stress-absorbing layer（ TSAL）. The results showthat the adhesive performance, shear performance, bending strength and fatigue performance of the EAGSAL with an optimal spraying volume of epoxy asphalt are better than those of optimally designed TSAL, and the maximum bending strain of the EAGSAL is very close to that of the TSAL. The EAGSAL has superior performance in reflective cracking resistance.Moreover, the EAGSAL with the optimal spraying volume of approximately 2. 0 L m^2 is thinner and lighter than the TSAL,which can decrease the thickness and improve the bearing ability of the whole pavement structure.

Indirect tension test of epoxy asphalt mixtureusing microstructural finite-element model

A finite-element model of the thermosetting epoxy asphalt mixture（EAM） microstructure is developed to simulate the indirect tension test（IDT）.Image techniques are used to capture the EAM microstructure which is divided into two phases：aggregates and mastic.A viscoelastic constitutive relationship,which is obtained from the results of a creep test,is used to represent the mastic phase at intermittent temperatures.Model simulation results of the stiffness modulus in IDT compare favorably with experimental data.Different loading directions and velocities are employed in order to account for their influence on the modulus and the localized stress of the microstructure model.It is pointed out that the modulus is not consistent when the loading direction changes since the heterogeneous distribution of the mixture internal structure,and the loading velocity affects the localized stress as a result of the viscoelasticity of the mastic.The study results can provide a theoretical basis for the finite-element method,which can be extended to the numerical simulations of asphalt mixture micromechanical behavior.

Evaluation of fracture properties of epoxy asphalt mixtures by SCB test

The fracture properties of epoxy asphalt mixtures （EAM） are evaluated based on J-integral and ultimate strength. Totally 60 semi-circular bending （SCB）specimens cored from superpave gyratory compactor （SGC）with three groups of notch depths are tested at the temperature of - 10 and 20 ℃. The experimental results reveal good repeatability in EAM characterization. The tensile strength ratio of SCB to the indirect tensile test （IDT） is at a range of 1.4 to 1.7, and the ultimate strength of EAM is exponentially dependent on the notch depths. At the test temperatures, the critical J-integral value of EAM is much higher than that of hot mix asphalt（ HMA） with thermoplastic asphalt binder. The response mode of EAM changes from ductile mode to brittle mode and the fracture energy increases 30% when temperature decreases from 20 to - 10℃, while its critical J-integral value decreases only 15%. It is concluded that EAM has better fracture resistance than thermo-plastic HMA; more fracture energy is needed to initiate cracks in EAM at low temperature, and the cracks propagate more rapidly than at room temperature.

Effects of freeze-thaw cycles on fracture behavior of epoxy asphalt concrete

According to the winter temperature of Peking,the freeze-thaw（FT） condition in laboratory was determined.Seven groups of epoxy asphalt concrete（EAC） specimen were exposed to different FT cycles.The flexural modulus and fracture energy（G_F） of EAC exposed to different FT cycles were obtained through the 3-point bending test.Meanwhile,the plane strain fracture toughness（K_（IC）） of EAC was obtained through numerical simulation.The results show that the flexural modulus of the FT conditioned EAC samples decreases with the increase of FT cycles.The FT damage of flexural modulus is 60%after 30 FT cycles.Nevertheless,with the increase of FT cycles,the G_F and K_（IC） of EAC decrease first and then increase after 15 FT cycles.

Experimental study on dynamic modulus of thermosetting epoxy asphalt mixture for steel deck pavement

In order to study the dynamic performance of the thermosetting epoxy asphalt mixture（EAM）, an experimental program on the dynamic modulus E is conducted. First, E of the EAM under different temperatures and frequencies are tested through the simple performance test（SPT）, and the effects of temperatures and frequencies on the dynamic modulus of the EAM are analyzed. Secondly, the static modulus of the EAM and the dynamic modulus of other two ordinary mixtures are tested and compared to E of the EAM. Finally the dynamic modulus master curve is constructed using the time-temperature superposition principle. The results show that the E values increase with the increase in the test frequency while on the other hand, the E values decrease with the increase in the test temperature. It also can be seen from the results that the dynamic modulus corresponding to the actual vehicle mode is significantly greater than the static modulus, and the dynamic modulus of the EAM is greater than that of SBS mixtures and the common hot mixed asphalt （HMA）. The study results can provide a theoretical basis for the design and mechanical analysis of the steel deck pavement.

Design and laboratory evaluation of fog-sealed chip seal on epoxy asphalt pavement for steel bridge deck

In order to improve the surface performace of epoxy asphalt pavement （EAP） for steel bridge deck, an epoxy asphalt chip seal （ ECS） covered by a cationic emulsified asphalt fog seal （i. e., fog-sealed chip seal） isproposed and a laboratory study is conducted to design and evaluate te fog-sealed chip seal. First, the evaluation indices and methods of te chip seal on steel bridge deck pavement were proposed. Secondly, the worst pavement conditions during te maintenance time were simulated by te small traffic load simulation system MMLS3 and the short-term aging test for minimizing the failure probability of chip seal. Finally, the design parameters of fog-sealed chip seal were determined by the experimental analysis and the performance of the designed fog-sealed chip seal was evaluated in thelaboratory. Results indicate that the proposed simulation method of pavement conditions is effective and the maximal load repetitions on the EAPslab specimen are approximately 925 300 times. Moreover, the designed fog-sealedchip sealcan provide a dense surface with sufficient skid resistance,aggregate-asphalt aahesive performance and interlayer shearing resistance.

Curing Behavior of Epoxy Asphalt

The curing process of epoxy asphalt was analyzed by Fourier transform infrared （FT-IR） spectroscopy. Effect of curing temperature on viscosity of epoxy asphalt, and changes of mechanical properties with curing time were investigated. The evolution of concentration of epoxy band was followed as a function of the applied curing process.The experimental results indicate that the curing reaction rate of epoxy asphalt is invariable before 70 min at 120 ℃, and it decreases when curing time exceeds 70 min. The viscosity of epoxy asphalt increases slowly with curing time at initial curing stage. But it increases quickly after initial curing stage and the initial curing time decreases as the curing temperature increases, The tensile strength increases slowly at incipient curing stage and increases rapidly when curing time is form 20 min to 70 min. The elongation at break shows a decrease with curing time, but it exceeds 200% after cured.

Fracture properties of epoxy asphalt mixture based on extended finite element method

Crack is found to be a major distress that affects the performance of the epoxy asphalt pavement.An extended finite element method was proposed for investigating the fracture properties of the epoxy asphalt mixture.Firstly,the single-edge notched beam test was used to analyze the temperature effect and calculate the material parameters.Then,the mechanical responses were studied using numerical analysis.It is concluded that 5℃ can be selected as the critical temperature that affects the fracture properties,and numerical simulations indicate that crack propagation is found to significantly affect the stress state of the epoxy asphalt mixture.The maximum principal stress at the crack surface exhibits different trends at various temperatures.Numerical solution of stress intensity factor can well meet the theoretical solution,especially when the temperature is lower than 5℃.

Fatigue damage analysis of epoxy asphalt pavement for steel bridges considering coupled effects of heavy load and temperature variations

To investigate the fatigue damage of epoxy asphalt pavement(EAP)under a heavy load and a d temperature load,the load-figure of the heavy load on the steel bridge deck pavement(SBDP)was simulated first,and the temperature distribution of SBDP during the temperature-fall period in winter was also calculated.Secondly,t e moving heavy load coupled W t the most unfavorable temperatre load was applied to the SBDP,and the tensile stress on the top of SBDP was calculated.Finally,the fatigue damage of EAP was evaluated considering the extreme situation of heavily overloaded and severe environments.The results show that botte heavy load and the temperature load during t e temperature-fall period c n increase the tensile stress on the top of SBDP significantly.In the exteme situation of heavily overloaded and severe environments,a fatigue crack is easily generated,and thus the SBDP should avoid t e coupling effects of the heavy loadand the temperature load in winter.

Hot Mixing Behavior and Curing Process of Epoxy Asphalt

A new hot mixed epoxy asphalt system was developed. The reaction process of epoxy resin was characterized by Fourier transform infrared spectroscopy (FTIR). The viscosity was investigated by Brinell viscometer when epoxy resin was mixed with asphalt. The glass transition temperature (Tg), homogeneity, thermal stability and viscoelasticity of epoxy asphalt were analyzed by differential scanning calorimetry (DSC), metallographic microscope, thermogravimetric (TG) and dynamic mechanical analysis (DMA). The results showed that the viscosity of epoxy resin modified asphalt reached 1000 mPa·s for more than 180 minutes at 180 ℃, while the best construction process is mixing at 180 ℃ for 2 hours and curing at 60 ℃ for 4 days. The particle size of asphalt is less than 50 μm. In addition, the mechanical properties of the materials are uniform within the specified pavement thickness.

Modelling the Rheological Properties of Epoxy Asphalt Concrete

This paper presents an investigation into modelling the rheological properties of epoxy asphalt concrete( EAC) by using the Huet-Sayegh model. Complex modulus tests were conducted on EAC specimens at various temperature and loading frequency conditions. Dynamic modulus and phase angles obtained from the complex modulus tests were used in the construction of the Huet-Sayegh model. The dynamic modulus master curve was developed by the Huet-Sayegh model as well as the Burgers model for comparison purpose. The results showed that EAC exhibits typical rheological behavior whose dynamic modulus decreases with the increase of temperature while increases with the increase of frequency,and phase angles increase with the decrease of frequencies and the increase of temperatures. The Huet-Sayegh model predicts the dynamic modulus master curve of EAC very well and much better than the Burgers model over a wide range of frequencies.

Fracture Behavior of Epoxy Asphalt Pavement on Steel Bridges based on Optical Fiber Sensing Technology and Numerical Simulation

The distributed optical fiber sensing technology was used to investigate the fracture behavior of the Epoxy Asphalt Mixture. The spatial distribution and variation of the strain development with crack propagation were acquired using the brillouin optical time-domain reflectometer through the loading experiments of the composite beam structure. In addition, a finite element model of the composite beam structure was developed to analyze the mechanical responses of the epoxy asphalt mixture using the extended finite element method. The experimental results show that the development of crack propagation becomes instable with the increase of the load, and larger loads will generate deeper cracks. Moreover, the numerical results show that the mechanical response of the crack tip changes with the crack propagation, and the worst areas that subjected to crack damage are located on both sides of the composite beam structure.

Curing Reaction Model of Epoxy Asphalt Binder

In order to understand the strength developing law of the epoxy asphalt mixture,a curing reaction model of the epoxy asphalt binder was proposed based upon the thermokinetic analysis.Given some assumptions,the model was developed by applying the Kissinger law as well as Arrhenius equation,and the differential scanning calorimetry was performed for estimating the model parameters.To monitor the strength development of the epoxy asphalt mixture,a strength test program was employed and then results were compared to those produced from the proposed model.The comparative evaluation shows that a good consistency exists between the outputs from test program and the proposed model,indicating that the proposed model can be used effectively for simulating the curing reaction process for the epoxy asphalt binder and predicting the strength development for the epoxy asphalt mixture.

Numerical analysis of the effects of subgrade settlement on top-down cracking in epoxy asphalt pavement

Epoxy asphalt pavement cracking caused by subgrade settlement is detrimental to the long-term safe service of roads.A threedimensional finite element model of epoxy asphalt pavement is established to investigate the effects of subgrade settlement on the propagation of top-down cracking(TDC).The contour integral method is utilized to calculate the stress intensity factor(SIF)at the crack tip,and then the extended finite element method(XFEM)is used to analyze the propagation behavior of TDC under combined subgrade settlement and traffic loading.The results of these analyses indicate that increased subgrade settlement,stiffer surface layers,and softer bases will increase the SIF,resulting in a faster crack propagation rate.It is suggested that the use of epoxy asphalt materials in pavement structures can allow more subgrade settlement than conventional asphalt mixtures.However,when the base layer modulus is higher than 12500 MPa,the increase in surface modulus can decrease crack propagation length.Sensitivity analysis results demonstrate that subgrade settlement has the most significant impact on TDC propagation.The conclusions of this study are expected to provide a theoretical basis for crack prevention in the design and maintenance of pavement structures.

Laboratory evaluation of epoxy resin modified asphalt mixtures

The pavement performance of epoxy resin modified asphalt mixtures was investigated by the Marshall test, the indirect tensile test, the rutting test, the three-pointed bending test and the composite beam fatigue test. In comparison with the performance of epoxy resin modified asphalt mixtures, the performance of stone matrix asphalt mixtures （SMA10） was also investigated. The rutting test and composite beam fatigue test results show that the epoxy resin modified asphalt mixtures can improve permanent deformation and fatigue characteristics. They also show lower temperature susceptibility and greater resistance to moisture damage compared to the SMA10. Findings from the research indicate that the epoxy resin modified asphalt mixture provides an optional material for the pavement of long-span steel bridges in China due to profound performance and economic advantages.

Evaluation of modification effect of epoxy resin based on performance of asphalt mixtures

Based on the analysis of the main failures discovered in pavement on steel deck plate and the demanding service condition of the pavement on steel deck, high-temperature rutting test, low-temperature bending test and controlled stress flexural fatigue test are used to study the performance of asphalt mixtures modified by epoxy resin including high-temperature stability, low-temperature cracking-resistance, and fatigue cracking-resistance, which are served to evaluate the modification effect of epoxy resin of different contents. With the addition of epoxy resin, all the three performances are improved greatly. However, when the amount of epoxy resin added is over a certain value, the modification effect will be stable with no extra benefit detected. Finally, in terms of the properties of the three respects, 20%, 30%, 30% are given separately as the proposal adding contents.