Epoxy Asphalt Mixture Research Articles

Compatibilization and toughness modification of linear aliphatic epoxy compound on paving epoxy asphalt

Epoxy asphalt (EA), which is usually prepared by diglycidyl ether of bisphenol A (DGEBA), curing agent and asphalt, is a kind of high-performance pavement material in highway construction. However, because of rigid molecular structure of DGEBA, poor compatibility with asphalt and high cross-linking density of three-dimensional network, cured EA usually has high strength but poor toughness especially at low temperature. In order to solve the problem of insufficient toughness of EA below glass-transition temperature (Tg) and eliminate the potential brittle fracture of EA mixture, linear aliphatic epoxy compounds, which have low viscosity, good molecular flexibility, similar solubility parameter and polarity with asphalt or DGEBA resin, can be used as phase structure controller and toughner to modify EA. By introducing a little of linear aliphatic epoxy compound, such as 1, 4-butanediol diglycidyl ether (BDDGE) or 1, 6-hexanediol diglycidyl ether (HDDGE), not only the viscosity of EA could be significantly decreased during the curing process, but also the phase compatibility of EA could be improved. An obvious reduction in storage modulus (E′) at low temperature and decreased Tg also prove that BDDGE or HDDGE modified EA have better toughness than neat EA at low temperature. The optimum amount of linear aliphatic epoxy compound based on its mixture with DGEBA should be 10–15 wt%.

Influence of Aggregate Packing on the Performance of Uncured and Cured Epoxy Asphalt Mixtures

AbstractThe skeleton structure has a strong influence on the uncured and cured performances of the epoxy asphalt mixture. Based on the Bailey method, the different skeletal structures of the mixtur...

Prediction of Paving Performance for Epoxy Asphalt Mixture by Its Time- and Temperature-Dependent Properties

As a type of thermosetting material, any improper or faulty operation of the epoxy asphalt cannot be rectified if the irreversible reaction has taken place. This has brought difficulties to the construction organization of epoxy asphalt pavement. The objective of this study is to evaluate the paving performance of epoxy asphalt mixtures (EAMs) and to predict the allowable time for paving and traffic opening. The viscosity curves of epoxy asphalt binder (EAB) were first measured under different reserved temperatures, and a viscosity growth model considering the time-temperature characteristic was proposed. The Marshall tests were also carried out on EAM under the preset reserved temperature and time to measure the Marshall stability (MS) and the air voids. The permissible reserved time at various reserved temperatures can be obtained through either the viscosity test on EAB or the Marshall test on EAM. The applicability of the two methods was compared, and the temperature influence was discussed. Additionally, the Marshall test results indicate that the relationship between the MS growth rate and the curing temperature follows the Arrhenius law: the traffic opening time of the EAM pavement can be forecast once the temperature-dependent rule is established. The results of this study can provide practical guidance to the mixing, paving, and curing processes of the EAM pavement.

Material and Structural Properties of Fiber-Reinforced Resin Composites as Thin Overlay for Steel Bridge Deck Pavement

Fatigue cracks are main damages to steel bridge deck pavement with thermosetting epoxy asphalt. By combining a high-toughness resin material with fiber woven fabrics, this study formed an ultrathin overlay of fiber-reinforced high-toughness resin to improve cracking resistance of pavement. Through theoretical measurement and bending test, this research studied change laws of bending and tensile properties of epoxy asphalt concrete after fiber reinforcement and analyzed bending strength and the maximum failure strain of beams at different temperatures. Moreover, the reinforcing effects of different fibers were discussed. It is found that bending strength, maximum failure strain, and stiffness modulus of the beams with epoxy asphalt are improved after fiber reinforcement. With the decrease of temperature, after fiber reinforcement, the mode of bending failure of the epoxy asphalt mixture (EAM) changes from brittle fracture into shear failure, accompanied with significant yield phenomenon. Furthermore, organic carbon fiber is sensitive to influences of temperature, while glass fiber is least sensitive to temperature.

Development of cold-mix high-toughness resin and experimental research into its performance in a steel deck pavement

Fatigue cracking is a typical defect in steel deck pavements. To reduce, or even eliminate, fatigue cracking in orthotropic steel deck pavements, a new-generation, cold-mix, high-toughness resin (CHR) for steel deck pavements was prepared by introducing a flexible chain into the molecular structure of cured epoxy resin based on the principle of action of a simultaneous interpenetrating polymer network (IPN). Meanwhile, the strength and durability of the CHR were studied experimentally. The results show that, with increased dosage of active toughening agent, the microstructure of CHR transitioned from a sea-island structure to an interpenetrating network structure. In addition, the transparency of CHR gradually increased and the tensile strength gradually decreased while the elongation at break gradually increased. The reaction orders of Z15-G1 and Z15-G2 CHRs were 0.918 and 0.921 and their apparent activation energies were 47.60 kJ/mol and 50.74 kJ/mol, respectively. The basic pavement performances of the Z15-G1 and Z15-G2 CHR mixtures both satisfied the technical index requirements of a steel deck pavement. Moreover, four-point bending fatigue test results show that the fatigue life of the Z15-G1 CHR mixture was much longer than that of an epoxy asphalt mixture.

Thermal Effect on Rheological Properties of Epoxy Asphalt Mixture and Stress Prediction for Bridge Deck Paving

AbstractEpoxy asphalt mixture has been widely used as an excellent paving material on long-span steel bridges; however, low-temperature cracking is a significant concern for paving on an orthotropi...

INCREASING THE PROPERTIES OF ASPHALT CONCRETES BY USING THE EPOXID FORMATION

One of the main reasons of low durability of asphalt concrete are the properties of bitumen which is the most sensitive of all its components to the action of external factors. As thermoplastic material, bitumen becomes soft at high summer temperatures leading to rutting, shear and sags formation. At low winter time temperatures it becomes fragile and rigid that due to low-temperature compression of asphalt pavement causes the occurrence of transverse cracks. The most effective direction for increasing the durability and roughness of asphalt pavement is changing the bitumen behavior by various types of additives modification. Among the issues related to all known modifiers, the least studied is the issue of using thermosetting polymers, namely, epoxy components. The main problem with the use of epoxy resins for modification is that under the influence of high process temperatures a rapid hardening of the epoxy resin after combining with the hardener occurs. Such behavior of epoxy components limits the temperature modes and the duration of process operations for the production, transportation and placement of epoxy asphalt mixtures. In this paper, the results of the study of epoxy-asphalt concrete obtained using the cut-back bitumen are presented. The dilution of bitumen allows reducing the process temperatures of the production of epoxy asphalt concrete mixtures which increases the time for their transportation and compaction. As a result of hardening of the epoxy resin, over time, a significant increase in the strength of the epoxy asphalt concrete occurs at all temperatures. The rate of hardening of epoxy asphalt depends on the temperature of the environment. As the temperature rises, the reaction rate between the epoxy resin and the hardener increases, which is reflected in the growth of the strength of the epoxy asphalt concrete at all test temperatures, the more intense evaporation of the solvent and, consequently, the growth of water saturation and the decrease in average density. Keywords. epoxy binder, epoxy asphalt concrete, epoxy resin, modification, cut-back bitumen.

Analysis of Viscoelastic Mechanical Response of Asphalt Mixture Pavement on Steel Deck under Imperfect Contact Conditions

Abstract For long-span steel bridges, the contact states between the pavement and the steel decks change significantly during the operation stage. Different interlayer contact states have different effects on the viscoelastic mechanical properties of the pavement. Here, the modified SMA10 mixture and the epoxy–asphalt mixture are compared in terms of the transverse tensile strain, the transverse tensile stress, and the deflection at the bottom of the asphalt layer under different contact conditions. The main curve clusters of the relaxation modulus were obtained using the creep test data, and the effects of four different contact conditions on the viscoelastic mechanical response of the asphalt mixture pavement of the Huangpu Suspension Bridge in China were analyzed accordingly. It was found that the delayed deformation capacity of the epoxy–asphalt mixture is better than that of the modified SMA10 mixture. The change of the interlayer contact condition has an impact on the viscoelastic mechanical response of the asphalt mixture pavement; for the modified SMA10 asphalt mixture pavement, the transverse tensile stress and the transverse tensile strain at the bottom of the pavement are more sensitive to the contact condition than the deflection. For the epoxy–asphalt mixture pavement, the deflection is more sensitive to the contact condition.

The mechanical behavior of epoxy asphalt mixture under cyclic loading

In order to investigate the mechanical behavior of epoxy asphalt mixture under cyclic traffic loading, cylindrical samples of the epoxy asphalt mixture were subjected to cyclic loading-unloading tests under varying confining pressures. The accumulation and dissipation of energy were observed in the energy evolutions. It turns out that the epoxy asphalt mixture exhibits elastic-plastic property in the first few cycles, and then the elastic property would be strengthened gradually in the cyclic loading tests. Applying a moderate confining pressure would significantly reduce the dissipated energy. The proportion of dissipated energy is about 25% from the unconfined test, and less than 15% from the confined test. As a result, more energy would be required if to produce equal permanent deformation under higher confining pressures. Therefore, a moderate increase in the confining pressure would be helpful in restraining permanent deformation, such as rutting.

Laboratory evaluation on functional characteristics of open-graded epoxy asphalt mixture

Epoxy asphalt binder is one kind of thermosetting asphalt binder composed by epoxy resin and asphalt mixed with curing agent in a certain temperature and a certain proportion. Relying on its excellent high temperature stability performance and strength characteristics, in recent years, epoxy asphalt has achieved successful application on many multi-span steel bridge deck pavement projects in China. In order to better grasp the functional characteristics such as drainage, noise reduction and anti-skid performance of open-graded epoxy asphalt mixture, this paper selects the epoxy asphalt as a cementing material to form OGFC4.75 and OGFC13 asphalt mixture. The permeable performance test, the pendulum test, the dynamic friction coefficient test and acoustic absorption coefficient test were applied to research the functional properties of epoxy asphalt mixture, the test results show that the larger size of OGFC gradation mixture has better permeability performance, then permeability performance of PG64 is slightly better than that of epoxy asphalt mixture. The pavement anti-skid performance of epoxy asphalt binder is better than that of PG64 asphalt binder. The acoustic absorption coefficient test shows that the epoxy asphalt can improve the noise reduction performance.

Modification of alkyl group terminated hyperbranched polyester on paving epoxy asphalt

Epoxy asphalt is a kind of high performance asphalt material that has been widely used in steel deck pavement. However, because high modulus and low toughness also exist in thermosetting epoxy asphalt mixture at low temperature, crack would be initiated by innerstress caused by temperature change. Hyperbranched polyester (HBP) is a kind of toughness modifier with low viscosity and high reactivity for thermosetting materials. It can effectively improve the toughness of thermosetting epoxy asphalt. However, hydroxyl end groups of HBP would accelerate the reaction rate of epoxy asphalt and disturb the phase dispersion between resin phase and asphalt phase. Therefore, it is necessary to modify the hydroxyl end groups of HBP as inert alkyl end groups to avoid its rapid curing reaction with epoxy resin. And by this, the excellent effects of HBP, such as viscosity reduction, compatibility improvement and toughening on thermosetting materials can be obviously observed in the HBP modified epoxy asphalt. Adding different alkyl end groups modified HBP into epoxy asphalt, not only the viscosity of epoxy asphalt can be reduced, but also the toughness of cured epoxy asphalt can be improved significantly.

Prediction and sensitivity analysis of long-term skid resistance of epoxy asphalt mixture based on GA-BP neural network

The objective of this study is to investigate the relationship between long-term skid resistance of epoxy asphalt mixture (EAM) and multiple engineering parameters involving mixture design parameters, construction parameters and operation parameters. Firstly, a database of 124 data sets was obtained, including optimal binder content, aggregate gradation characteristics, bulk specific gravity, air-void content and load repetitions for input parameters, and long-term skid resistance of EAM simulated by an accelerated pavement test for output. Secondly, using the database, an optimized GA-BP neural network model (i.e. GA-BP model) was established to predict the long-term skid resistance, and then a comprehensive sensitivity analysis was conducted to explore the effect of input parameters on the skid-resistant evolution based on the trained neural network. Results show that the optimized GA-BP model can effectively predict the long-term skid resistance of EAM, and the long-term skid resistance has a significant negative correlation with binder content and shape characteristic of aggregate gradation. In addition, bulk specific gravity is the most important factor influencing the long-term skid resistance, and also has the most remarkable interaction effect with other input parameters.

Performances evaluation of epoxy asphalt mixture containing snow-melting agent

The performance degradation of the asphalt mixture blended with the snow-melting agent can inevitably occur although it can be relieved by adding the high viscosity modifier or Nanopowder. The thermosetting epoxy asphalt binder, different from the conventional thermoplastic asphalt as SBS modified asphalt, was adopted in this research to solve this problem. Experiments were carried out to test the road engineering performances, conductivity, deicing and snow melting performances of epoxy asphalt mixture with the snow-melting agent content of 6%, 7% and 8%, substituting the equivalent amount of mineral filler, and then the results were compared with SBS modified asphalt mixture. The results show that snow-melting agent has a slight influence on the engineering performance of epoxy asphalt mixture. With snow-melting agent content or environmental temperature rising, the snow-melting agent release amount and rate of epoxy asphalt mixture increase, but are lower than those of SBS modified asphalt mixture under the same condition. The epoxy asphalt mixture with snow-melting agent can provide preferable snow melting performance and low ice adhesion. This thermosetting mixture with snow-melting agent possesses engineering application potential due to its excellent performance and long snow melting life.

Investigation on surface characteristics of epoxy asphalt concrete pavement

The mechanical performance of epoxy asphalt concrete has been well reported in existing studies. This study investigated the surface characteristics of asphalt concrete, including the permeability, friction coefficient, moisture damage resistance and surface texture. The permeability test, dynamic friction test, Cantabro test, Hamburg test and laser texture scanning test were carried out for such investigations. Test results show that the permeability of the epoxy asphalt concrete was very low, which is desirable for protecting the steel deck. The friction coefficient can satisfy the requirement for steel deck bridge according to the Pendulum Number. However, it was found that the skid resistance could be a concern when the vehicle speed is higher than a certain level according to the dynamic friction test. The results suggested to control the traffic speed when epoxy asphalt concrete is applied as steel bridge pavement. In terms of the raveling and stripping, it was found that the epoxy asphalt mixture has an excellent anti-stripping performance based on the Cantabro test and Hamburg wheel tracking test results. The yield point was not reached after 20,000 loading cycles at 60°C in the immersed Hamburg wheel tracking test. The mean profile depth of the epoxy asphalt concrete is 0.305mm, much lower than conventional asphalt concrete indicating a very fine surface texture.

Influence of foaming effect, operation time and health preserving properties of foam epoxy asphalt mixtures

Epoxy asphalt is provided with excellent performance. However, its construction time is too short for the current situation in China, which therefore has brought about the issues with harsh conditions, high costs and risks. In order to solve this problem, this paper proposes a new foamed epoxy asphalt (FEA), and adopts a new curing system. To investigate the hardening system effect on foamed epoxy asphalt, 3 key points in FEA research have been proposed, namely foaming effect, influence of waiting time for compacting during construction, and strength grows in health preserving. Conventional Marshall method is used for the preparation of the testing specimens. The results obtained showed that the optimum foaming temperature is 120°C, with the optimum water consumption being 2% relatively; the minimum compacting temperature of FEA mixt is 56°C, and its longest waiting time for compacting is 6h. At least 50days of health preserving time is recommended after the completion of the construction of the FEA paving, which equals to 24h at a constant temperature of 60°C preserving for the future laboratory study due to the time-temperature equivalence rule.

Study and Application on Cold Blended Epoxy Asphalt Mixture for Steel Bridge Deck Pavement

New cold blended epoxy asphalt material and ERS pavement structure were used for steel deck pavement of Zhijiang bridge. In this paper, the material and structural performance were evaluated by laboratory tests. For the cold blended epoxy asphalt, the optimum composition ratio, construction time and temperature requirements were determined through viscosity and tensile performance test. The road performance of epoxy asphalt mixture was evaluated by high temperature rutting test, low temperature bending test and moisture damage test. Through 45 ° oblique shear test and composite beam fatigue test. The structural properties such as interlayer bonding state and fatigue performance were evaluated. The experimental results showed that the new type of cold blended epoxy asphalt had high breaking elongation, high tensile strength and loose construction time under normal temperature;RA05 mixture had excellent road performance; The shear strength of ERS waterproof adhesive layer reached 5MPa at 25°C and 2MPa at 70°C; RA05 and SMA10 had close bonding，good cooperative performance and great fatigue property to resist large deformation. Overall, ERS material and structure had excellent road performance and mechanical properties. The effect of the application in Zhijiang bridge was great.

Laboratory investigation and numerical simulation of the rutting performance of double-layer surfacing structure for steel bridge decks

To optimize the surfacing structures for steel deck bridges, this study proposed new pavement structures combining two types of common surfacing mixtures, and evaluated their rutting resistance performance. A total of five pavement structures from different combinations of gussasphalt, epoxy asphalt, and stone mastic asphalt mixtures were analyzed. First the rheological characteristics of the three mixtures were obtained through a repeated simple shear test at constant height (RSST-CH). Creep parameters of the three materials were then estimated through nonlinear multiple regression analysis based on the Bailey-Norton creep model. With the estimated creep parameters, finite element models of orthotropic steel deck pavements were built to simulate permanent deformation of deck pavements at 60°C. The simulation results were then verified by a wheel track rutting test. The study shows that in a two-layer deck pavement structure consisting of the same layer material, rutting failure mainly occurs in the surface layer. Findings from this study may be used in the design of steel deck pavement materials and structures for improved high-temperature performance.

Design and skid resistance evaluation of skeleton-dense epoxy asphalt mixture for steel bridge deck pavement

To improve the skid-resistance of epoxy asphalt concrete pavement for the steel bridge deck, an epoxy asphalt mixture with skeleton-dense structure was proposed. This paper carries out a laboratory study on the design and performance evaluation of skeleton-dense epoxy asphalt mixture. Firstly, the mixture was designed through a volume design method, and the pavement performance was investigated to evaluate the applicability of the skeleton-dense epoxy asphalt mixture for the steel bridge pavement. Secondly, the skid-resistance of the skeleton-dense epoxy asphalt mixture was evaluated, including the initial skid-resistance, long-term skid-resistance and skid-resistance under the inclement weather condition. The long-term skid-resistance attenuation law was simulated by the small traffic load simulation system MMLS3, and the skid-resistance life was predicted. The skid-resistance attenuation law under the rainy and freezing weather was investigated in the laboratory, and the influence of water film thickness, different ice situations on the pavement skid-resistance was analyzed. Finally, gray correlation analysis method was applied to the comprehensive evaluation of pavement skid-resistance. Results indicate that the proposed mixture could meet the operating requirements of steel bridge pavement and dramatically improve the skid-resistance of epoxy asphalt concrete pavement.

A pothole patching material for epoxy asphalt pavement on steel bridges: Fatigue test and numerical analysis

Various patching materials and field procedures have been studied for pothole repairing on highway asphalt pavements. However, only a few publications have focused on patching materials for epoxy asphalt pavement on steel bridge decks. Considering the requirements of steel deck pavements, a patching material was developed using a fast cure thermosetting binder and a fine gradation. Then, to evaluate the fatigue performance of patched structure, a three-point bending fatigue test was conducted on three types of composite beams under four different stress ratios. After that, the Prony series presentation of the generalized Maxwell model was used to analyze the viscoelastic response of different patched beams and the effect of viscoelastic difference. The results showed that the fatigue test performed well on exposing the vulnerable parts of patched structures. The developed patching material had a smaller dynamic modulus and performed better in fatigue resistance than commonly used epoxy asphalt mixture. Nevertheless, with the growth of viscoelastic difference between patching material and original material, the stress state on vertical patching interface becomes worse, and the interface becomes easier to fracture under cyclic load.

Design and laboratory evaluation of small particle porous epoxy asphalt surface mixture for roadway pavements

To improve the smoothness and to increase the durability of pavement surface with porous asphalt mixtures, a small particle porous asphalt mixture modified with epoxy resin is proposed. This paper presents a laboratory study on the design and performance evaluation of small particle porous epoxy asphalt mixture. The mixture was designed based upon a binder drainage test and a raveling test. Mixture properties, including high temperature stability, low temperature crack resistance, moisture resistance, friction, and permeability, were evaluated in the laboratory. The results show that the proposed mixture has good mechanical properties while retaining satisfactory friction resistance and permeability.