Creep Compliance Research Articles

Evaluation of waste toner asphalt containing crude palm oil from Congo: Rheological properties, compatibility, self-healing and aging characteristic

This study investigates the impact of bio-based additives on waste toner-modified asphalt binder (WTMA) properties. Congo crude palm oil (CCPO) and waste banknote toner (WT) were chosen as modifiers. Rheological properties, including high-temperature behavior, fatigue resistance, and low-temperature performance, were evaluated using dynamic shear rheometer (DSR) and bending beam rheometer (BBR). Storage stability, Aging index, Self-healing, Fluorescence microscopy (FM), and Fourier Transform Infrared Spectroscopy (FTIR) tests were conducted. Results showed that the CCPO reduces WTMA viscosity, leading to lower mixing and compaction temperatures. However, CCPO inclusion decreases rutting performance, evidenced by reduced rutting factor (G*/sinδ) and % recovery (R), and increase non-recoverable creep compliance (Jnr). Fatigue resistance of CCPO/WT composite-modified asphalt surpasses that of WTMA. Similarly, CCPO/WT composite-modified asphalt exhibits higher resistance to low-temperature cracking. Moreover, CCPO addition reduces phase separation in WTMA, enhancing compatibility. Waste toner improves binder self-healing properties, although CCPO initially impacts WTMA’s self-healing ability negatively. Nevertheless, CCPO/WT composite-modified asphalt demonstrates higher self-healing capability compared to the base asphalt.

Assessment of indirect tensile stress and tensile–strength ratio and creep compliance in HMA mixes with micro-silica and PMB

Abstract This study aims to ascertain the effects of polymer-modified bitumen (PMB) and to utilize mineral filler with micro-silica (MS) on various properties of hot-mix asphalt (HMA). In this work, three specimens of an asphalt-concrete mixture were prepared. The first specimen represents a control mixture, the second specimen contains MS at rates 15, 30, and 45% by the total weight of the total aggregate as filler, and the third specimen contains MS and PMB with 4% novolac by the weight of bitumen and 15% hexamine by the weight of the novolac. The properties of designed mixes were evaluated using the indirect tensile strength test, tensile–strength ratio, and creep compliance. The test results showed an increase in the resistance of asphalt concrete to moisture damage, a reduction influence of water on asphalt concrete properties, creep compliance values indicating growing stiffness for asphalt mixture, and enhanced fatigue life. In conclusion, using 45% MS and PMB improved the properties of HMA and provided long-lasting mixtures for highway construction.

Accurate and efficient determination of glass thermo-viscoelastic properties using creep compliance master curve construction approach

An accurate and efficient method for determining the thermo-viscoelastic properties of glass was proposed using a creep compliance master curve construction approach based on the time-temperature superposition principle. This method mainly involved obtaining creep compliance at multiple temperatures, constructing the master curve, and converting into relaxation modulus. By applying this method, the shear relaxation modulus and Williams-Landel-Ferry constants were successfully obtained for K9 glass. A smooth creep compliance master curve at 590 °C was constructed covering a vast timescale up to 2.6×105 seconds, despite a single curve's duration being only 619 seconds. Consequently, the derived relaxation modulus encompassed a broad range of relaxation times spanning six orders of magnitude. The high accuracy of the determined thermo-viscoelastic properties was firmly validated across all tested temperatures. Furthermore, the detrimental impact of friction on the method's accuracy can be effectively minimized by selecting a suitably large height-to-diameter ratio for the cylindrical glass specimen.

Effects of hydrocolloids on mechanical properties, viscoelastic and microstructural properties of starch-based modeling clay

The effects of various hydrocolloids (guar gum, xanthan gum, and carboxymethyl cellulose) on the texture, rheology, and microstructural properties of modeling clay prepared with cassava starch were investigated. Notably, incorporation of 3 % guar gum and 4 % xanthan gum into starch-based modeling clay resulted in enhancements of 94.12 % and 77.47 % in cohesiveness, and 64.70 % and 66.20 % in extensibility, respectively. For starch-based modeling clay with added guar gum and xanthan gum, compared to formulations without hydrocolloids, the linear viscoelastic range exceeded 0.04 %, and the frequency dependence of both maximum creep compliance (Jmax) and storage modulus (G′) was significantly reduced. This indicates a more stable network structure and enhanced resistance to deformation. Results from Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD) confirmed that the physical interactions between starch and various hydrocolloids, along with the addition of these hydrocolloids, inhibited the degradation effect of thermomechanical processing on the crystalline structure of starch. With the addition of guar gum, it is observed that a continuous and dense network structure forms within the starch-based modeling clay, and starch particles are distributed uniformly. In conclusion, hydrocolloids enhances the properties of starch-based modeling clay, introducing an innovative solution to the modeling clay sector.

Evaluation of hard petroleum asphalt's low-temperature performance and index optimisation based on the grey correlation model

Hard petroleum asphalt (HPA) has good application prospects because of its simple manufacturing process and excellent performance. However, according to previous studies, the performance of HPA at low temperatures cannot be well characterised by commonly used methods. The use of HPA in cold climates is severely constrained. In order to comprehensively evaluate the low-temperature performance of the material, this study used four different types of HPA as the research object, and used the bending beam rheological test ( BBR) to determine the basic rheological properties of the material. On this basis, after fitting and analysing the low-temperature creep compliance curve using the Burgers viscoelastic model, the asphalt was assigned a low-temperature viscoelastic assessment index. The glass transition temperature and sensitivity of HPA were investigated by differential scanning calorimetry (DSC). At the same time, the HPA assessment index at low temperatures was determined systematically by using grey correlation theory.

Assessment of performance characteristics of pavement base course incorporating reclaimed asphalt pavement and asphaltenes

Asphalt pavement is demolished and milled at the end of its service life, resulting in an enormous amount of waste material known as reclaimed asphalt pavement (RAP). Using cold recycling techniques, it is possible to reuse RAP for base course construction. However, using a high amount of RAP could have negative effects on the mechanical properties and durability of the base course. In this study, to improve the performance of asphalt emulsion recycled base course prepared with RAP, asphaltenes derived from Alberta oil-sands bitumen was added to the mixture. The performance properties of the selected mixtures were investigated at high, intermediate, and low temperatures. Testing results and statistical analysis revealed that asphaltenes enhances the high and intermediate temperature performance of the modified mixes significantly. The low-temperature creep compliance of asphaltenes-modified mixtures was slightly lower than the unmodified mixtures, however, the low-temperature properties of the modified mixes were not significantly affected.

Application of the Arrhenius Equation in Predicting the Temperature Susceptibility of Unmodified and Modified Bituminous Binder

Bitumen is a temperature-susceptible material. The performance of the bitumen largely depends on the sensitivity of its characteristic properties to the variation in temperature. This paper uses the Arrhenius equation to predict the temperature-sensitive properties of various bitumens. Three modified and unmodified binders of various grades were tested under study shear, frequency mode (oscillatory shearing), and time mode (multiple stress creep and recovery) at different temperatures from 10 to 70ºC. This paper focuses on the activation energy to understand the temperature-susceptible behavior of the bitumen and the influence of aging on the bitumen. To analyze the temperature susceptibility of the bitumen, Steady shear, MSCR, and LAOS tests were performed. From these tests, parameters such as viscosity, dynamic modulus, energy dissipation, and creep compliance at different temperatures were observed to follow the Arrhenius equation. The activation energy constant of the Arrhenius equation is found to vary with the characteristic function used. It is also statistically proven that the activation energy depends on the shear rate or shear stress, indicating that the temperature-susceptible properties of the bitumen are shear rate-dependent. Also, as the bitumen ages, its temperature-susceptible properties improve. Doi: 10.28991/CEJ-2024-010-03-015 Full Text: PDF

Assessing the effects of copolymer modifier addition on asphalt attributes: Towards achieving performance optimization

The use of polymers to modify asphalt binders has become a widely accepted practice in modern pavement construction, offering a promising solution to address key factors contributing to asphalt pavement deficiencies. These factors include issues such as rutting, moisture-induced deterioration, and fatigue-related wear. The copolymer referred to as PGXpand was utilized as the modifying additive for the virgin binder in this study. It demonstrates exceptional performance in terms of high-temperature resilience and resistance to rutting. The impact of incorporating the PGXpand on asphalt properties was investigated. A comprehensive series of tests were conducted, covering storage stability, penetration, softening point, ductility, viscosity, and elastic recovery. Further analyses involved calculations of stiffness modulus, complex modulus, and phase angle. Mechanical and performance evaluations were also carried out, including Marshall properties, moisture susceptibility, creep compliance, and Kim tests. The results demonstrate the effectiveness of the PGXpand in enhancing asphalt performance, with modified mixtures exhibiting significant improvements compared to their unmodified counterparts. Consequently, integrating the PGXpand into asphalt technology emerges as a highly promising approach for optimizing road infrastructure, especially in regions with high-temperature conditions. Ultimately, such integration contributes substantially to the development of sustainable and resilient transportation networks.

Effect of Industrial Solid Waste as Fillers on the Rheology and Surface Free Energy of Asphalt Mastic.

The continuous growth of industrial solid waste production has generated many environmental problems. We evaluated the potential of industrial solid waste as a substitute filler in asphalt mastic, with the aim of increasing the use of sustainable road construction materials. In this study, X-ray fluorescence spectroscopy (XRF) and scanning electron microscopy (SEM) were used to characterize the oxide composition and micromorphology of limestone (LS), red mud (RM), steel slag (SS), and ground granulated blast-furnace slag (GGBFS). Four asphalt mastics containing LS, RM, SS, and GGBFS with a filler-to-binder weight ratio of one were prepared. An evaluation of the rheology and wetting of the solid-waste-filler asphalt mastic was conducted using a frequency sweep, temperature sweep, linear amplitude sweep (LAS), multiple stress creep and recovery (MSCR), and surface free energy (SFE) methods. The results showed that SS increased the complex modulus, elastic component of the asphalt mastic and decreased the nonrecoverable creep compliance at stress levels of 0.1 and 3.2 kPa, which improved the rutting resistance of the asphalt mastic and reduced deformation under high-temperature conditions. The RM and GGBFS increased the fatigue performance of the asphalt mastic under strain loading, enhanced its fatigue life, and maintained good performance under long-term loading. The dispersive component of the SFE parameter of the solid-waste-filler asphalt mastic was larger than the polar component for the largest share of the surface energy composition. The SFE of the asphalt mastic prepared from the industrial solid-waste filler was reduced; however, the difference was insignificant compared to the limestone asphalt mastic. Solid-waste-filler asphalt mastic has performance characteristics, and its actual application can be based on different performance characteristics to select an appropriate solid-waste filler. The results of this study provide new technological solutions for solving the utilization rate of solid waste materials and sustainable road construction in the future.

Study on Viscoelastic Properties of Various Fiber-Reinforced Asphalt Binders.

This study analyzed the viscoelastic properties of asphalt binders reinforced with various fibers, such as modified asphalt binder, modified asphalt binder reinforced with lignin fibers (LFs), polyester fibers (PFs), and polypropylene fibers (PPFs), using dynamic shear rheological (DSR) testing. Then, the experiment generated data on the dynamic modulus and phase angle, which described the dynamic rheological characteristics at varying temperatures. The generalized Maxwell model was employed to select the appropriate element, and the test curve was fitted into a discrete time spectrum based on the time-temperature equivalence principle (TTSP). The master curves of the relaxation modulus and creep compliance were established to predict the relaxation and creep properties of various asphalt binders. The analysis indicated that fiber-reinforced binders offer superior resistance to high temperatures and long-term deformation, while being less sensitive to temperature and having a more significant elastic characterization. The binders reinforced with PPFs and LFs exhibited superior performance in high-temperature settings and long-term durability, respectively. On the other hand, the binder reinforced with PFs displayed exceptional high-temperature elastic properties. Additionally, based on the experimental data and corresponding discussion, it appears that the 13-element GM model is more appropriate for fitting the data.

Low stress creep response of PTFE sealants applied to PEM fuel cells

AbstractViscoelastic properties of polytetrafluoroethylene (PTFE) play a crucial role in forecasting its long‐term behavior in engineering applications. An attempt is made to explore the viscoelastic properties of PTFE sealants that are utilized in polymer electrolyte membrane fuel cell (PEMFC). It is to be noted that PTFE sealants are vulnerable to creep under constant loading at elevated temperatures. Moreover, the creep of sealants will lead to leakage of reactants from the cell, which affects the performance of PEMFC. PTFE is an excellent choice as a sealant material in low‐temperature polymer electrolyte membrane fuel cell (LT‐PEMFC), which operates in the temperature range of 60–80°C. PTFE can be prominently used as sealants in high‐temperature polymer electrolyte membrane fuel cell (HT‐PEMFC), as it possesses no significant change in its physical properties within the temperature range of −150 to 300°C along with the working conditions of HT‐PEMFC. In LT‐PEMFC, the sealants will typically be subjected to low stresses in the range of 1–5 MPa. In this article, the creep response of PTFE sealant material is extensively studied at various temperatures of 25 (room temperature), 35, 45, 55, and 65°C and at three stress levels of 2, 3, and 4 MPa. The time–temperature superposition principle is utilized to develop master curve at a reference temperature of 25°C, to forecast long‐term creep characteristics of PTFE sealants. Moreover, the master curve for creep compliance is developed for 4.5 h.

Improving the properties of hot applied crack sealant by utilizing Pre-activated Crumb Rubber (PCR)

Crack sealing stands as a cost-effective pavement maintenance practice and has a typical life span of 1–3 years. To enhance sealants’ longevity and optimize their performance, evaluating potential material modification, particularly in hot and arid regions, is of interest. In this research study, a comprehensive testing protocol was designed to address prevalent failure modes observed in asphalt crack sealants such as adhesion, cohesion, pumping, and settlement failures. The primary modification involved the incorporation of Pre-activated Crumb Rubber (PCR) at varying concentrations (2.5%, 5%, and 7.5%) by weight of the sealant. Testing was conducted on both unaged and short-term aged sealant samples with different PCR contents. The findings revealed promising improvements associated with PCR concentrations up to 5%, manifesting as enhanced elasticity, toughness, tenacity, flexibility at low temperatures, and resistance to shear thinning at high temperatures. For a content of 5% PCR, the results show a decrease of the non-recoverable creep compliance (Jnr) of 60% for 0.1kPa and 81% for 3.2kPa loading conditions when compared to the control sealant. Furthermore, an increase in toughness and tenacity of 72% and 25% respectively was measured for the aged conditions. In terms of shear thinning resistance, the coefficient “P” increased from 0.75 to 0.83 indicating a greater resistance to tracking. The results indicated favorable trends with the addition of the modifier, yielding potential improved performance in the field.

Evaluation of Rheological Properties of Polymer-Modified Asphalt Binders and Mastics with Organic Additive—Imidazoline

The article presents the results of testing the asphalt binder modified with SBS copolymer (5%) and its mixture with mineral fillers called asphalt mastics. The aim of the research and analysis was to check the possibility of using an organic additive in the form of imidazolines and to assess their impact on the viscoelastic properties of the obtained asphalt mastics. The main advantage of using imidazoline is the increased resistance of asphalt mixtures to low-temperature cracking at the top of the road route and reducing its maintenance costs. Based on the examination of the adhesion of the binder with the addition of various imidazolines to the aggregate, a selection was made from six analyzed subtypes. One of them was selected for further research. The tests were carried out in a dynamic shear rheometer in a wide temperature range from −36 °C to 82 °C, determining the most important parameters of the tested materials, i.e., dynamic shear modulus (|G*|), phase angle (δ) and the non-recoverable creep compliance (Jnr). The test results and their analysis confirmed the beneficial effect of imidazoline on the viscoelastic properties of mastics in the low-temperature range, even at the lowest content of 0.2%. Based on the results of the determination of Jnr and |G*|/sinδ in the range of high operating temperatures, no significant deterioration in permanent deformation parameters was observed. Moreover, the use of imidazoline reduces technological temperatures during the production of HMA used in the pavement and, therefore, reduces CO2 emissions into the atmosphere.

Laboratory Evaluation of Tensile Creep Behavior of Concrete at Early Ages

Short-term uniaxial tensile creep tests were conducted for early-age concrete at different ages in an effort to characterize early-age concrete as an aging viscoelastic material. Based on the test results, the viscoelastic material properties of the test concrete were characterized in terms of the Dirichlet series creep compliance and relaxation modulus functions. Applications of the model to the numerical analysis of the test samples showed a good agreement between the tests and computational results for the samples tested at different ages. This paper presents the test procedures and data analysis with a brief introduction of theoretical background.

Molding law of traditional Chinese medicine gel plaster based on physicochemical properties of raw materials and intermediates

This paper aims to study the correlation between the physicochemical properties of raw materials and intermediates and the molding quality and law of traditional Chinese medicine(TCM) gel plaster by using TCM slices and powder as raw materials. 48 TCM compounds are selected as model prescriptions to prepare gel plasters. The rotational rheometer is used to determine the rheological parameters of the plaster, including storage modulus(G'), loss modulus(G″), yield stress(τ), and creep compliance [J(t)]. The molding quality of the prepared TCM gel plaster is evaluated by subjective and objective measures. Clustering and principal component analysis are conducted to evaluate the physical properties of the plaster. By measuring the rheological properties of the plaster, the molding quality of the TCM gel plaster can be predicted, with an accuracy of 83.72% after seven days of modeling and 88.37% after 30 days of modeling. When the parameters such as G' and G″ of the plaster are large, and the [J(t)] is small, the molding quality of the plaster is better. When the plaster coating point is no less than 3, it is difficult to be coated. In addition, when the proportion of metal ions in the prescription is higher, the 30-day forming quality of the plaster is mainly affected, and the viscosity of the plaster is poor. If the prescription contains many acidic chemical components, the 7-day forming quality of the plaster is mainly affected, with many residuals. The results suggest that the rheological properties of the plaster can be used to predict the molding quality of TCM slice and powder gel plaster. It can provide a reference for the development of TCM gel plaster prescriptions.

Characterization of viscoelastic behavior of basalt fiber asphalt mixtures based on discrete and continuous spectrum models.

In order to analyze the differences between the master curves of relaxation modulus E(t) and creep compliance J(t) obtained from discrete and continuous spectrum models, and to comprehensively evaluate the effect of basalt fiber content on the viscoelastic behavior of asphalt mixtures, complex modulus tests were conducted for asphalt mixtures with fiber content of 0%, 0.1%, 0.2% and 0.3%, respectively. Consequently, the master curves of Viscoelastic Parameters of asphalt mixtures were constructed according to the generalized Sigmoidal model(GSM) and the approximate Kramers-Kronig (K-K) relationship. Then, transformation of master curves using discrete and continuous spectrum models to obtain the models of E(t) and J(t) containing all viscoelastic information. Also, the accuracy of the models of E(t) and J(t) was evaluated. The results show that the addition of basalt fibers improves the strength, stress relaxation and deformation resistance of asphalt mixtures. It is worth noting that basalt fibers achieve the improvement of asphalt mixtures by changing their internal structure. Considering the different viscoelastic master curves at four dosages, the optimum fiber dosage was 0.2%. In addition, both discrete and continuous model conversion methods can obtain high accuracy conversion results.

Experimentally informed modeling of the early‐age stress evolution in cementitious materials using exponential conversion from creep to relaxation

AbstractThis study presents comprehensive numerical modeling methods for simulating early‐age stress (EAS) relaxation in cementitious materials, based on the autogenous deformation (AD), elastic modulus, creep, and stress continuously tested by a mini temperature stress testing machine (Mini‐TSTM) and a mini AD testing machine from a very early age (i.e., from a few hours to a week). Four methods for converting creep compliance to relaxation modulus were discussed in detail and used for the one‐dimensional (1D) and three‐dimensional (3D) simulation of stress evolution in the Mini‐TSTM test. Furthermore, virtual creep and relaxation tests were conducted using an exponential algorithm with either the Kelvin or Maxwell chains to show their applicability in simulating the viscoelastic behavior of early‐age cementitious materials. The results showed that the exponential algorithm with the Maxwell chain using an exponential conversion function from creep to relaxation obtains good prediction accuracy of EAS in 3D analysis. The numerical solutions of the Volterra integral of creep compliance can lead to a negative relaxation modulus, thus introducing stress calculation errors in both 1D and 3D analysis.

Modelling nonlinear shear creep behaviour of a structural adhesive using deep neural networks (DNN)

Structural adhesives have seen a surge in applications for bonding Fibre reinforced polymers to strengthen structures. However, being polymeric materials, they can exhibit viscoelasticity, leading to creep, which can adversely affect bonded strengthening systems. This paper delves into the nonlinear shear creep behaviour of a typical structural adhesive using a machine learning approach. A deep neural networks (DNN) model was trained using a dataset of 7176 data points obtained from 25 sets of butt joint shear creep tests performed at various stress levels and temperatures. The DNN model successfully captures the complex relationship between temperature, stress, time, and shear creep with a performance value of R2 larger than 0.99. The creep compliance curves predicted by the model are in close agreement with the experimental results, highlighting the ability of the DNN model to effectively model the complex nonlinear shear creep behaviour, which is difficult to achieve with traditional physics-based viscoelastic models. The SHapley Additive exPlanations analysis further identified temperature as the most significant factor influencing the creep, followed by stress and time. The constructed DNN model and its corresponding analyses can provide a valuable reference for the structural adhesive to limit the negative effects of creep in practical applications.

Lowering added sugar and increasing fibre in croissants using short-chain fructooligosaccharides (sc-FOS)

This work explores the potential of short-chain fructooligosaccharides (sc-FOS) as a sugar replacer in bakery products, particularly croissants. The effects of sucrose replacement with sc-FOS on croissant dough properties, as well as the quality of baked croissants, are studied. It was found that the changes in croissant on inclusion of sc-FOS are primarily related to changes in water redistribution and the binding state of water in the dough, with minimal role of change in secondary structure of proteins. Rheological properties of sugar-reduced croissant dough were characterized. The use of sc-FOS as a sucrose replacement increased storage and loss moduli, indicating enhanced interactions and a firmer dough. Creep compliance revealed less deformation and improved elastic recovery, suggesting strengthened bonding, especially in the gluten network. The upper crust of croissants showed no significant differences in colour, but the lower crust darkened slightly with sc-FOS. Texture analysis revealed a firmer texture with complete sucrose replacement, while the porosity remained consistent. Sensory evaluation indicated changes in hardness and overall acceptability with sc-FOS, emphasizing the need for reformulation and consideration of the impacts on starch gelatinization.

Evaluation of Mechanical Performance of Asphalt Emulsion Stabilized Base Course Composed of Reclaimed Asphalt Pavement and Asphaltenes

Abstract Reclaimed asphalt pavement (RAP) is a material that is produced by milling old asphalt pavement that can be mixed with virgin asphalt binder and aggregates to fabricate a recycled asphalt mixture. Using RAP in pavement structure can promote sustainability and reduce construction costs. In this study, asphaltenes, which is a waste material derived from oil sands deasphalting operation, was added as a modifier to recycled mixtures composed of different contents of RAP. A proctor test was conducted to determine the optimum fluid contents. Mix designs were performed for mixtures with 50 %, 75 %, and 100 % RAP with asphalt emulsion and different asphaltenes contents. Mechanical properties of the modified mixtures were evaluated by conducting the indirect tensile strength (ITS) test, creep compliance and strength test, indirect tensile asphalt cracking test (IDEAL-CT), and Hamburg wheel tracking test. The optimum emulsion content was determined to be 1.5 % based on sample performance using the ITS test. The results indicate that asphaltenes improves the strength up to the design-specified limits. The asphaltenes-modified samples show lower creep compliance and fracture energy (FE) values than the unmodified sample, indicating these samples are potentially more prone to cracking. Further, statistical analysis shows the difference in FE is significant at the lowest testing temperatures (−20°C). Asphaltenes-modified mixtures have greater cracking resistance at the intermediate temperature (25°C) and rutting performance at high temperature (40°C) than the unmodified mixture. However, based on FE and rutting resistance index, the improvements are not significant. Overall, the 100 % RAP mix with 1 % asphaltenes had the best tensile strength, cracking resistance, rutting resistance, and low temperature properties compared to other modified mixes.