Uniaxial Creep Tests Research Articles

A two-scale method to rapidly characterize the logarithmic basic creep of concrete by coupling microindentation and uniaxial compression creep test

A recent survey has showed the prediction of the long-term deflection of existing concrete bridges after several decades is a great challange in civil engineering. The crux is to predict the creep deflection of a concrete structure after several decades from laboratory tests carried out over few months. This work aims at combining microindentation tests and as short as possible Uniaxial Compression Creep Test (UCCT) to characterize the modulus C and the characteristic time τch of the compliance function of basic creep used in modern design codes.First, concrete samples made of cement paste, mortar and concrete with a water-to-cement ratio of 0.6 were cured and loaded in sealed condition at a age of 90 days under UCCT for a duration of 1 year. A convergence study showed that the duration of UCCT which is needed to accurately estimate the characteristic time τch and creep modulus C is about 30 days and 300 days, respectively. Then, the creep modulus C was measured by microindentation tests on the cement paste and homogenized at the scale of mortar and concrete by micromechanics. Finally, the compliance creep function obtained by the proposed two-scale method was compared to experimental results which are available in open literature and other ones of existing design models, such as the model code 2010 and the well-established B4 model. As main result, the proposed simplified method which combines short (2-month) UCCT and rapid microindentation tests showed to be practical and accurate to characterize the basic creep compliance function of concrete.

Optimization of Burgers creep damage model of frozen silty clay based on fuzzy random particle swarm algorithm

The creep characteristics of frozen rock and soil are crucial for construction safety in cases of underground freezing. Uniaxial compression tests and uniaxial creep tests were performed at temperatures of − 10, − 15, − 20, and − 25 °C for silty clay used in Nantong metro freezing construction to investigate the effect law of the stress–strain curves and creep curves. However, owing to the complex effects of factors such as temperature and ground pressure, the mechanical properties of underground frozen silty clay are uncertain. The Burgers creep damage model was established by using an elastic damage element to simulate the accelerated creep stage. The traditional particle swarm optimization algorithm was improved using the inertia weight and the fuzzy random coefficient. The creep parameters of the Burgers damage model were optimized using the improved fuzzy random particle swarm algorithm at different temperatures and pressure levels. Engineering examples indicated that the optimized creep model can more effectively characterize the creep stages of frozen silty clay in Nantong metro freezing construction. The improved fuzzy random particle swarm algorithm has wider engineering applicability and faster convergence than the traditional algorithm.

Investigations on Creep Behavior and Fractal Derivative Constitutive Model of Sandstone under Different Drying-Wetting Cycles

Sandstone has been regarded as an optimal medium for underground gas storage (UGS). To better understand effects of drying-wetting (D-W) cycles on creep behavior of sandstone, comprehensive experimental investigations including uniaxial compression test (UCT) and uniaxial constant-load creep test (UCCT), were conducted on sandstone specimens under different D-W cycles. Experimental results demonstrate that the UCS and E, instantaneous strain, and steady creep rate of sandstone are greatly influenced by D-W treatment. Steady creep rate of sandstone increases with the increase in stress and D-W cycles, while both the UCS and long-term strength (σ∞) of sandstone specimens gradually decrease with the increase in D-W cycles. A novel fractal derivative creep constitutive model of sandstone considering the variations of viscosity coefficient and D-W cycles is established, which could accurately describe the creep characteristics of sandstone after different D-W cycles in the whole creep process. The influence of D-W cycles on the sensitivity of creep parameters is analyzed to discuss the influence of D-W cycles on creep and damage behavior of sandstone.

Creep Characteristics of Different Saturated States of Red Sandstone after Freeze-Thaw Cycles

To investigate the creep mechanical characteristics of rocks in different saturated states after freeze-thaw cycles, samples with different saturations (30%, 50%, 70%, 90%, and 100%) were selected for nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and uniaxial compression creep tests. The internal microscopic damage of the rock sample and mechanical characteristics under long-term loading are analyzed after the action of freeze-thaw cycles. The test results show that, as the saturation increases, the T2 spectrum distribution shifts to the right. The spectrum area gradually increases as the porosity increases. The critical saturation of freeze-thaw damage occurs when the saturation increases from 70% to 90%. It can be seen from the SEM image that the number of pores inside the rock samples gradually increases with increases in saturation, leading to the appearance of cracks. Under long-term loading, the saturation has a significant influence on the time-efficiency characteristics of sandstone freeze-thaw. As the saturation increases, the creep deformation gradually increases. After reaching 70%, the axial creep strain increases significantly. The rate of creep is accelerated, the creep failure stress is reduced, and the creep time under the last level of stress is significantly increased. A modified viscous-plastic body is connected in series to the basic Burgers model, the freeze-thaw-damage viscous element is introduced, and the creep parameters are fitted using test data. The results will provide a reference for long-term antifreeze design for rock engineering in cold areas.

Experimental Investigations on Creep Behavior of Coal under Combined Compression and Shear Loading

The creep behavior of rock has received much attention for analyzing the long-term response and stability of underground rock engineering structures. Numerous studies have been carried out on the creep properties of various rocks under pure compression conditions. However, little attention has been paid to the creep behavior of rocks in a combined compression-shear loading state. In this work, a novel combined compression and shear test (C-CAST) system was used to carry out inclined uniaxial compression tests and creep tests for various inclination angles (0°, 5°, 10°, and 15°). The results revealed that the peak strength of the coal decreased with the inclination angle of the specimen, which could provide the basis for setting up a creep test scheme. Multistage compression-shear creep tests were carried out on specimens with different inclination angles. Based on the analysis of the creep test data, the creep behavior of the coal in a combined compression-shear state was studied. It was found that the specimen inclination affected the time-dependent deformation, long-term strength (LTS), and time to failure. Compared with the specimen under pure compression, the inclination specimens tend to produce large shear strain with time, while they were more prone to shear failure. The reduction of the long-term strength was closely associated with the increase of the specimen inclination angle when the angle was more than 5°. Moreover, the ratio of the peak strength to the LTS was not affected by the specimen inclination, which is considered an inherent characteristic. We anticipate that the results obtained will assist in pillar design and long-term stability analysis.

A general fractional model of creep response for polymer materials: Simulation and model comparison

AbstractThe creep deformation of polymer materials is a major concern to ensure the safety and reliability of structural designed parts. In this work, a novel fractional creep model is established by introducing the superb Almeida‐Caputo fractional derivative into the traditional viscoelastic constitutive equation. The kernel function is determined by conducting several simulations of uniaxial creep tests, making it more flexible and reliable to provide excellent description of creep deformation. Compared to the traditional fractional model, the proposed model exhibits higher accuracy and better performance, and is found to have the ability to depict the nonlinear time‐varying characteristic at accelerated creep stage. Furthermore, the physical significance of fractional order is explored by performing the sensitivity analysis of model parameters, the results revel that the order is closely associated with the evolution of material properties where the diagrams of creep deformation of polymer materials under elevated temperature and stress levels could be mirrored by the variation of fractional order.

Creep damage evaluation via uniaxial miniature testing for multiaxially stressed Mod.9Cr–1Mo steel components

In this study, creep damage in a biaxially creep-damaged Mod.9Cr–1Mo component has been examined via uniaxial miniature creep testing. Using cruciform specimens, biaxial tension creep tests were conducted at principal stress ratios (λ) of λ=0.0 and 1.0 at 923 K. The principal stress ratio is the ratio of the y-directional principal stress (σy) to the x-directional principal stress (σx) in a cruciform specimen (λ=σy/σx). The equi-biaxial creep test was interrupted at a half lifetime, and two miniature specimens were machined from the damaged cruciform specimen in the x- and y-direction. The applicability of the linear cumulative creep damage rule was assessed using the results of the miniature lifetimes. The linear cumulative creep damage rule gave an unconservative estimate to the remaining life of a biaxially damaged cruciform specimen. Using the hyperbolic constitutive relationship, the unconservative estimate according to the damage accumulation was explained.

Influence of creep constitutive models for an Al[sbnd]Si[sbnd]Cu alloy on load distribution of bolted joint

Creep of materials under high temperature conditions will greatly affect the reliability of bolted connections. This current paper focuses on the influence of the creep constitutive model for an AlSiCu alloy material on the load-bearing law of threaded teeth under high temperature environment. In order to obtain more accurately the creep law of the AlSiCu alloy in high temperature environment, the uniaxial tensile creep tests at 250 °C, 300 °C and 350 °C were carried out on the AlSiCu alloy specimens. Two creep constitutive model parameters are obtained by fitting the creep test data respectively. Then, the bolt connection combination structure model is established, and the bearing law of the bolt connection combination structure under different temperatures is calculated by ABAQUS, and the influence of the two creep constitutive models on the thread load law is analyzed. The results indicate that the modified Graham creep constitutive model has little effect on the load-bearing distribution of threads at 250 °C, and the time-hardening creep constitutive model has little effect on the load-bearing distribution of threads at 300 °C and 350 °C.

Creep behaviour of WC-12 wt% Co hardmetals with different WC grain sizes tested in uniaxial tensile and compression step-loading tests at 700 °C and 800 °C

At elevated temperatures, the material behaviour of WC-Co hardmetals shows differences under similar loading conditions depending on WC grain size and Co-content. Variations in the chemical composition and microstructure in hardmetals cause different material properties such as strength or creep resistance. In the current work, the influence of WC grain size on creep mechanism and creep resistance was investigated for WC-12 wt% Co hardmetals with 0.4 μm, 0.7 μm and 2.0 μm average WC grain size. Specimens were tested in uniaxial tensile and compression step-loading creep tests at 700 °C and 800 °C under vacuum conditions. Time-dependent creep behaviour with steady-state secondary creep was observed for all hardmetal grades investigated, with specimens creeping faster under tensile than under compressive loading. At 700 °C, the medium-grained hardmetal grade exhibited the highest minimal creep rates ε̇min compared to the submicron and ultrafine-grained grades. In contrast, the ultrafine-grained hardmetal grade showed higher ε̇min at low stresses and 800 °C, because of the high amount of grain boundary area per unit volume, which is advantageous for vacancy diffusion at grain boundaries. Therefore, the ε̇min of the medium-grained hardmetal grade was less affected by temperature than that of the finer-grained grade. Also two stress exponent n-ranges were observed at 700 °C and 800 °C: At low stress levels, n was in the range of about 1. Above a critical stress level, n reached values between about 4 and 6. Beside the influence of the WC grain size on the creep mechanism and creep resistance, damage evolution with increasing stress levels was analysed for the ultrafine-grained grade at 800 °C. The microstructures of three compression step-loading creep tested specimens were examined after maximum stress levels of −350 MPa, −950 MPa and −1350 MPa. Microstructural investigations performed via scanning electron microscopy showed that more and larger cavities had formed at WC/WC interfaces and WC/Co phase boundaries in the specimen tested up to −1350 MPa compared to the ones tested up to −350 MPa and −950 MPa.

Study on the Time-Dependent Mechanical Behavior and Springback of Magnesium Alloy Sheet (AZ31B) in Warm Conditions.

In this study, the time-dependent mechanical behavior of the magnesium alloy sheet (AZ31B) was investigated through the creep and stress relaxation tests with respect to the temperature and pre-strain. The microstructure changes during creep and stress relaxation were investigated. As the tensile deformation increased in the material, twinning and dynamic recrystallization occurred, especially after the plastic instability. As a result, AZ31B showed lower resistance to creep and stress relaxation due to dynamic recrystallization. Additionally, time-dependent springback characteristics in the V- and L-bending processes concerning the holding time and different forming conditions were investigated. We analyzed changes of microstructure at each forming temperature and process. The uniaxial tensile creep test was conducted to compare the microstructures in various pre-strain conditions with those at the secondary creep stage. For the bending process, the change of the microstructure after the forming was compared to that with punch holding maintained for 1000 s after forming. Due to recrystallization, with the holding time in the die set of 60 s, the springback angle decreased by nearly 70%. Increased holding time in the die set resulted in a reduced springback angle.

Effects of moisture content and tillage methods on creep properties of paddy soil.

The rheological properties parameters of paddy soil affect the interaction between the tillage tools and soil, thus influencing the operation quality and power consumption. In order to study the effects of tillage methods and moisture content on the rheological properties parameters of paddy soil in the middle and lower reaches of the Yangtze River, uniaxial compression creep tests of paddy soils with four moisture contents under no tillage (moisture contents: 26.71%, 24.52%, 23.26%, 21.28%) and plough tillage (moisture contents: 26.77%, 25.55%, 23.40%, 20.56%) were carried out using a TMS-PRO texture analyzer. The creep properties curves obtained from the tests, and the rheological constitutive equation of paddy soil under compression was established by Burgers viscoelastic model. Respectively, the quantitative change rules of creep properties of paddy soil with different moisture contents under different tillage methods and the correlation between these parameters were explored. The results showed that the moisture content under the three-year plough tillage and no tillage methods had significant influence on the rheological properties parameters of paddy soil (P < 0.05). The instantaneous elastic modulus, delay elastic modulus, and viscosity coefficient of the two paddy soils (no tillage and plough tillage soils) decreased with the increase of moisture content. However, the variation rules of relaxation time and delay viscosity coefficient with moisture content differed between these two paddy soils. Specifically, the strain rate of the two paddy soils decreased as moisture content decreased, where the total strain combines elastic strain, viscous strain, and viscoelastic strain. The initial strain rate and steady strain rate of the plough tillage paddy soils were lower than that of the no tillage paddy soils. The established creep model equation could be used to obtain viscoelastic rheological parameters of paddy soil in a wide range. The fitting equations between rheological parameters and moisture content were introduced into Burgers model, and the coupling equations between creep deformation and moisture content and time were derived, which could be used to predict the creep properties and deformation behavior of paddy soil in a certain range of no tillage and ploughed field. Overall, this study has a certain theoretical significance for the development and improvement of paddy soil rheology theory, and can also provide theoretical basis and technical support for the research of agricultural machinery design optimization, field water, soil conservation, soil tillage and compaction related simulation analysis in the middle and lower reaches of the Yangtze River.

A novel nonlinear creep model based on damage characteristics of mudstone strength parameters.

Mudstone interlayer is a weak layer in rock engineering. When it is subjected to continuous stress higher than its damage threshold, due to the dislocation of particles in mudstone crystals and the expansion of cracks, mudstone strength is gradually damaged and deteriorated and the strain gradually increases, thus accelerating the phenomenon of creep damage. In order to describe the characteristics of the whole process of mudstone aging deformation, based on the damage evolution of strength parameters (cohesion and internal friction coefficient) with stress and time in mudstone creep tests, a novel damage nonlinear viscoelastoplastic body (D-NVPB) is proposed through improving traditional plastic element. D-NVPB describes the nonlinear characteristics of the accelerated creep stage of mudstone. With the element combination method, D-NVPB is connected with the Burgers model in series to form a new nonlinear damage creep model (D-NVEP model). The analysis results of creep characteristics theoretically verified the rationality of the model in describing the instantaneous elasticity, viscoelasticity, and nonlinear viscoplastic characteristics of the complete creep curve of mudstone. With the data obtained in the uniaxial compression creep test of mudstone under the action of a stress level of 14 MPa, based on the Levenberg-Marquardt nonlinear least squares method, the fitting calculation was performed through piecewise fitting and overall fitting. The correlation coefficient was 0.9909, which verified the applicability of the model. The obtained model parameters by the identification were used to predict the mudstone creep curve under the stress levels of 13 MPa and 15 MPa. The good prediction results further verified the feasibility of the model. Compared with the traditional creep model, the D-NVEP model can better describe the nonlinear characteristics of the accelerated creep stage and quantitatively display the strength damage evolution process of rock in the creep failure process.

Performance Deterioration of Asphalt Mixture under Chloride Salt Erosion

In order to ensure smooth traffic and driving safety, deicing salt or snow melting agents are usually adopted to solve the problem of traffic jams and prevent pavement surfaces from freezing. The objective of this present study is to investigate the performance deterioration evaluation of asphalt mixture under the chloride salt erosion environment. Five chloride salt solution concentrations were designed and the uniaxial static compression creep test, low-temperature IDT test, freeze-thaw splitting test, and freeze-thaw cycle test were carried out for asphalt mixtures (AC-16) soaked in chloride salt solution. Results showed that with the increase in chloride salt solution concentration, the high-temperature stability, low-temperature crack resistance, and water stability of the asphalt mixture decreases. Moreover, the high-temperature stability, low-temperature crack resistance, and water stability of the asphalt mixture show a decreasing trend under different chloride salt solution concentrations following the negative cubic polynomial function. Based on the viscoelastic analysis, chloride salt solution could reduce the ability of the asphalt mixture to resist instantaneous elastic deformation and permanent deformation, and this influence will become more obvious with the increase in chloride salt solution concentration. In addition, the salt freeze-thaw cycle test indicated that in the early stage of freeze-thaw cycles, the splitting tensile strength of the asphalt mixture decreases rapidly, then tends to be flat, and then decreases rapidly. This study explores the performance damage law of asphalt mixture under salt corrosion, and the analysis results of this study could provide some references for the chloride salt dosage in the snow melting project while spreading deicing salt.

Tensile creep mechanical behavior of periodontal ligament: A hyper-viscoelastic constitutive model

ObjectiveIn orthodontic treatment, the biomechanical response of periodontal ligament (PDL) induces tooth movement. Coupling modeling of PDL can effectively reflect its biomechanical response. The nonlinear creep mechanical behavior of PDL was studied by uniaxial tensile creep test and a new hyper-viscoelastic constitutive model. Two coupling modeling methods with limitations were excluded. MethodsPDL specimens were prepared from the central incisors of pig mandible. The theoretical step function was replaced by static loading with a total loading time of 1 s. The creep loading with the constant stresses of 0.05, 0.1, and 0.15 MPa was selected and kept unchanged for 1000 s. The instantaneous hyperelastic mechanical behavior and time-dependent nonlinear viscoelastic mechanical behavior of PDL were characterized by coupled instantaneous third-order Ogden hyperelastic and time-dependent nonlinear creep models. ResultsThe results showed that the instantaneous elastic curve of PDL increases in the form of hyperelastic index. The creep strain and creep compliance curves increase rapidly before 200s, and then increase slowly in steady state. The creep strain increased with an increase in the constant stress; conversely, the creep compliance decreased with an increase in the constant stress. The results showed that the experimental data were highly consistent with the hyper-viscoelastic constitutive model (R2>0.97). SignificanceWe normalize the framework of hyper-viscoelastic coupling modeling (Instantaneous hyperelastic model + time-dependent nonlinear viscoelastic model). Which can be extended to other nonlinear viscoelastic biomaterials.

Thermo-Mechanical Behavior of Poly(ether ether ketone): Experiments and Modeling.

Observations are reported on poly(ether ether ketone) (PEEK) in uniaxial tensile tests, relaxation tests and creep tests with various stresses in a wide interval of temperatures ranging from room temperature to 180 °C. Constitutive equations are developed for the thermo–mechanical behavior of PEEK under uniaxial deformation. Adjustable parameters in the governing equations are found by matching the experimental data. Good agreement is demonstrated between the observations and results of numerical simulation. It is shown that the activation energies for the elastoplastic, viscoelastic and viscoelastoplastic responses adopt similar values at temperatures above the glass transition point.

An Investigation into the Correlation of Small Punch and Uniaxial Creep Data for Waspaloy

Within the aerospace sector, the understanding and prediction of creep strains for materials used in high-temperature applications, such as Nickel-based super alloys, is imperative. Small punch testing offers the potential for understanding creep behavior using much less material than conventional uniaxial testing but in contrast to uniaxial creep tests, the stress in small punch creep (SPC) tests is multiaxial. SPC testing can be a valuable tool for validating models of creep deformation, but the key to unlocking its full capability is through the accurate correlation of the creep material properties measured through both techniques. As such, the focus of this paper is to correlate the creep behavior of Waspaloy obtained through conventional uniaxial testing to that obtained via small punch creep testing. Recently, and for low chrome steels, this has been achieved through use of the ksp method, but there are good reasons for believing this technique will not work so well for Nickel-based super alloys. This paper shows this to be the case for Waspaloy and proposes some alternative methods of correlation based on combining the Monkman–Grant relation and the Wilshire equations for both uniaxial and small punch creep. It was found that this latter approach enabled the accurate conversion of SPC minimum displacement rates to equivalent uniaxial minimum creep rates which, when combined with the Wilshire equations, enabled SPC test loads to be converted into equivalent uniaxial stresses (and visa versa) with levels of accuracy that were significantly reduced when compared to using the ksp method. Further, the random error associated with these conversions were dramatically increased.

Experimental investigations and numerical simulations of innovative lightweight glass\u2013plastic-composite panels made of thin glass and PMMA

Composites are being increasingly used for industrial applications and combine the advantageous properties of two or more constituents. The urge to reduce material to a minimum and the trend towards lightweight glass structures require further developments in high performance and fully transparent composite structures for the building industry. Novel innovative glass–plastic-composite panels combining a lightweight polymer polymethylmethacrylate (PMMA) interlayer core and cover layers of thin glass are currently under development. The panels exhibit high structural load-bearing performance, are durable and fully transparent with a low self-weight. These properties make the composite panels suitable for slender and lightweight glass constructions and reveal new design possibilities for the building industry. However, the material properties of the modified PMMA polymer interlayer core for precise design considerations are lacking. Furthermore, the material behaviour of thermoplastic polymers changes over time, ages due to environmental influences and is temperature-dependent. This significantly affects the composite load-bearing behaviour and defines the limits of application for the composite panels in the building industry. In order to facilitate during the development process and to build a design basis for the composite panels, material model parameters and simulation methods are required. Hence, an extensive test programme was conducted to investigate the material properties of the PMMA interlayer core by means of dynamic mechanical thermal analysis as well as uniaxial tensile and creep tests. The dataset and subsequent implementation into finite element software allowed for realistic simulations of the glass–plastic-composite panels and an extension of experimental results. Numerical simulations were performed with the commercial finite element programme ANSYS Workbench 19.3. Additionally, four-point bending tests were performed on composite test specimens with a different build-up and conventional glass panels to validate the material model and finite element simulations. These investigations and adopted material properties formed the basis for a numerical parametric study to evaluate the influence of stiffness, the load-bearing and lightweight performance in different build-ups. All the results are evaluated in detail and discussed in comparison with conventional monolithic and laminated glass panels. The dataset and material model parameters can be applied to further developments and design of lightweight glass–plastic-composite panels for structural applications in the building industry.

Comprehensive study on mechanical properties of coated biaxial warp-knitted fabrics

In recent years, coated fabrics have become the major material used in membrane structures. Due to the special structure of base layer and mechanical properties, coated biaxial warp-knitted fabrics are increasingly applied in pneumatic structures. In this article, the mechanical properties of coated biaxial warp-knitted fabrics are investigated comprehensively. First, off-axial tensile tests are carried out in seven in-plane directions: 0°, 15°, 30°, 45°, 60°, 75°, and 90°. Based on the stress–strain relationship, tensile strengths are obtained and failure modes are studied. The adaptability of Tsai–Hill criterion is analyzed. Then, the uniaxial tensile creep test is performed under 24-h sustained load and the creep elongation is calculated. Besides, tearing strengths in warp and weft directions are obtained by tearing tests. Finally, the biaxial tensile tests under five different load ratios of 1:1, 2:1, 1:2, 1:0, and 0:1 are carried out, and the elastic constants and Poisson’s ratio are calculated using the least squares method based on linear orthotropic assumption. Moreover, biaxial specimens under four load ratios of 3:1, 1:3, 5:1, and 1:5 are further tensile tested to verify the adaptability of linear orthotropic model. These experimental data offer a deeper and comprehensive understanding of mechanical properties of coated biaxial warp-knitted fabrics and could be conveniently adopted in structural design.

The creep strength of aberrant grade 91 steel

ABSTRACT The high-temperature steel grade 91 is intended to operate in service with a fully martensitic microstructure, achieved by a well-defined heat treatment. Unfortunately, lack of control, either during the initial material manufacturing or later during post-weld heat treatment, can lead to components entering service in a substandard condition. In the worst cases, this can be a fully ferritic microstructure with a complete absence of martensite. In this aberrant condition, the steel can have a creep strength significantly lower than that of normal martensitic grade 91 with an associated risk of early failure in plant life. This paper reports on investigations into the creep strength of aberrant grade 91,,using both conventional uniaxial rupture testing and small-scale impression creep testing. The creep strength has been found to fall into the range mean-35% to mean-50% in terms of stress relative to the most recent (2019) ECCC rupture life assessment of grade 91.

A Nonlinear Fractional Viscoelastic-Plastic Creep Model of Asphalt Mixture.

The mechanical behavior of asphalt mixture under high stresses presents nonlinear viscoelasticity and permanent deformation. In this paper, a nonlinear fractional viscoelastic plastic (NFVEP) creep model for asphalt mixture is proposed based on the Nishihara model, with a Koeller spring-pot replacing the Newton dashpot. The NFVEP model considers the instantaneous elasticity, viscoelasticity with damage and time-hardening viscoplasticity with damage concurrently, and the viscoelastic response is modeled by fractional derivative viscoelasticity. To verify the model, uniaxial compressive creep tests under various stresses ranging from 0.4 MPa to 0.8 MPa were carried out at room temperature. The NFVEP model predictions are in good agreement with the experiments. The comparison with the modified Nishihara model and the Burgers model reveals the advantages of the NFVEP model. The results show that the NFVEP model, with the same set of parameters, can not only describe the primary and steady-state creep stages of asphalt mixture under low stress levels but also the whole creep process, including the tertiary creep stage, of asphalt mixture under high stress levels.