•Fumed silica nanoparticles (FSNs) readily form a network structure within the bitumen matrix, thereby enhancing its elasticity.•The nanoscale characteristic and branched chain-like structure of FSNs ...improve the rheological properties of bitumen.•FNSs tend to reduce the effects of thermo-oxidative and UV aging on binder properties.•Fumed silica has a better price and modification effect than nano silica.
Inorganic nanofillers such as nano silica (nano-SiO2) modifiers can enhance the rheological and anti-aging performance of bitumen. However, nanoparticles are susceptible to aggregation and are considered costly for modifying a bituminous pavement. In this study, fumed silica nanoparticles (FSNs) are proposed as a novel bitumen modifier, which is only 1/10 the price of conventional nano-SiO2. The properties of FSNs are compared with those of organically modified nano-SiO2 (MNS) and ordinary SiO2 (OS) particles. Firstly, the surface morphology of OS, MNS, and FSNs is examined through field emission scanning electron microscopy (FESEM). The rheological, chemical, and thermal properties of base and silica-modified bitumen are investigated before and after different aging methods. The results reveal that FSNs readily form a network structure in the bitumen matrix, which effectively enhances the bitumen's elasticity and deformation resistance at high temperatures. Furthermore, regardless of the aging method used, FSNs dramatically reduce the complex modulus aging index of bitumen, demonstrating their resistance to thermo-oxidative degradation and ultraviolet radiation aging. The Fourier transform infrared (FTIR) spectra indicate that FSNs effectively reduce the carbonyl index of bitumen due to their chemical stability and barrier properties. The differential scanning calorimetry (DSC) results show that the glass transition temperature (Tg) of FSN-modified bitumen does not change much after aging, which is due to the inhibition of the conversion of light components into asphaltene during the aging process. Therefore, the FSNs can be considered as a cost-effective and promising modifier for increasing the durability of bitumen.
Magnetorheological elastomers (MREs) are a group of smart composite materials which are composed of magnetic particles dispersed in an elastomeric matrix. The controllable dynamic properties of these ...materials rely on many factors, in which temperature is a significant influencing factor requiring further investigations. In this paper, the dynamic mechanical analysis (DMA) tests have been performed to determine the viscoelastic properties of MREs with different test conditions. Based on the experiment results, the dynamic properties of MREs is modelled respectively by fractional Maxwell model (FMM) and generalized Maxwell model (GMM), and then the master curve of complex modulus is constructed using the time–temperature superposition (TTS) principle. The results show that the transition behavior of the silicon rubber based MRE samples under uniaxial compression occurs at about 50 °C. The storage modulus exhibits two different trends with the temperature variation: It first decreases rapidly and then increases slightly or maintains a stable value with increasing temperature.
The need for a viscoelastic characterisation of hot mix asphalt is increasing as advanced testing and modelling is incorporated through mechanistic-empirical pavement design and performance-based ...specifications. Viscoelastic characterisation includes measurement of the mixture stiffness and relative proportion of elastic and viscous response. The most common method is to measure the complex modulus, where dynamic modulus represents the stiffness and the phase angle represents the relative extent of elastic and viscous response. Determination of phase angle from temperature and frequency sweep tests has been challenging, unreliable and prone to error due to a high degree of variability and sensitivity to signal noise. There are also large amounts of historical dynamic modulus data that are either missing phase angle measurements or have poorly measured phase angle data that inhibit their use in further evaluation. This paper evaluates the robustness of phase angle estimation from stiffness data for asphalt mixtures. The objectives of the study are to: (1) evaluate the procedure of estimating phase angle from the slope of log-log stiffness master curve fitted with a generalised logistic sigmoidal curve and compare it with lab measurements and the Hirsch model; (2) assess the effect of measured and predicted phase angles on a mixture Black Space diagram; (3) evaluate the effect of using predicted phase angles on SVECD fatigue analysis particularly regarding damage characteristics curves and fatigue coefficients and (4) evaluate the impact on layered viscoelastic pavement analysis for critical distresses (LVECD) pavement fatigue performance evaluation due to the use of predicted phase angles. Three sets of independent mixtures were evaluated in this study comprising a wide range of mixture conditions. The results indicate good agreement between measured and predicted phase angle values in terms of shape and peak master curve values. In terms of magnitude, the values from both matched very well for certain sets of mixtures and subsequently manifested in similar performance predictions. However, for other sets of mixtures, a considerable difference was observed between measured and predicted phase angle values as well as SVECD and LVECD results. The differences may be attributed to the use of different types of linear variable displacement transducers (loose core versus spring loaded). Another possible explanation for the difference could be the contribution of plastic strain, which may create a difference in phase angles of 1-2°.
•Master Curve approach has been successfully employed with mini-C(T) specimens of four structural steels: S275JR, S355J2, S460M and S690Q.•Contribution to the validation of mini-C(T) specimens for ...the determination of T0. To the authors’ knowledge, very limited research has been conducted on non-nuclear steel grades.•Fractographical analysis of the fracture surfaces confirms cleavage fracture following the weakest link theory (i.e., one single initiation point), as required by the Master Curve.•T0 values obtained with mini-C(T) specimens were compared with conventional specimens. These values were also favorably compared to the results presented in literature for nuclear steels.
This work uses mini-C(T) specimens, validated on nuclear steel grades, to characterize the fracture behavior of structural steels. Mini-C(T) specimens are significantly smaller (4 mm thick) than conventional fracture specimens and allow testing a large number of specimens with limited material. The research involves four common structural steels (S275JR, S355J2, S460M and S690Q), and involves testing, ASTM E1921 application and fractographical analyses. Findings demonstrate that mini-C(T) specimens effectively capture the fracture behavior of structural steels, providing reasonable T0 values. Results show a difference of about ±30 °C comparing mini-C(T) and conventional specimens, suggesting the potential of mini-C(T) specimens for T0 characterization.
•The existing breakage models are found incompetent in oblique impact.•Literature impact breakage databases are collected for model assessment.•A proposed oblique impact model shows its novelty in ...unifying breakage curve.•The oblique impact model can be integrated with any normal impact breakage models.
Many experimental and numerical studies have been performed on the impact breakage of particulate solids, leading to a variety of impact breakage models developed to predict breakage probability. Ideally, impact breakage models would be mechanistic in nature, mathematically simple and inclusive of critical breakage parameters. In this paper, a critical review of the most widely used impact breakage models is presented, with the conclusion that the majority of existing breakage models inadequately predict breakage probability under oblique impact. In this work, a novel oblique impact model is proposed where the effect of impact angle is considered by the equivalent velocity. A breakage database compiled from the literature is deployed to interrogate the validity of the proposed model across a variety of oblique impact circumstances. In this way, the new oblique impact model is shown to provide excellent predictions of breakage probability, requiring only one set of fitting parameters under various impact angles. The unique feature of this oblique impact model is not necessarily required to be used with any specific normal impact breakage models, but can instead be universally applied with any of the assessed normal impact breakage models to establish unified breakage master curves for any oblique impact.
•A method for constructing the temperature master curve of asphalt is proposed.•Temperature frequency equation effectively achieves the conversion of two indicators.•Temperature master curve ...accurately predicts modulus variation with temperature.•Temperature master curve was applicable to asphalt with different aging extents.
Master curve is widely applied to assess the rheological properties of asphalt. The traditional master curve describes the variation of asphalt rheological properties with frequency. However, compared to frequency, the influence of temperature on asphalt properties is of greater concern. This study attempted to establish a method to transform the traditional master curve into temperature master curve. To this end, asphalt binder with different aging extents were prepared using aging simulation tests, and traditional complex shear modulus master curves of asphalt binder were established based on frequency sweep test. These were then transformed into temperature master curves using the established temperature-frequency equation. Furthermore, the accuracy of the temperature master curve was assessed through temperature sweep tests. The results showed that the temperature-frequency equation obtained based on Williams Landel Ferry equation effectively described the relationship between temperature and reduced frequency. The temperature master curve demonstrated good applicability for asphalt at different aging levels, with the differences between complex shear modulus values calculated by temperature master curve and the experimental values generally within 20%. The temperature master curve accurately characterized the trend of complex shear modulus with temperature. However, this accuracy and applicability were primarily focused on the mid-temperature and high-temperature ranges. The temperature master curve had obvious deficiency in predicting the complex shear modulus at low temperature. The findings provide new methods and insights into the relationship between asphalt rheological properties and temperature.
•Components distribution of SBS modified asphalt binder is presented.•Master curve of the complex modulus (|G∗|) and phase angle (δ) of SBS modified asphalt are depicted.•Phase angle (δ) is more ...sensitive to asphalt composition and aging.•Compared to complex modulus, the master curve of phase angle (δ) has more characteristics.
The simultaneous polymer degradation and asphalt oxidation of polymer modified asphalt (PMA) binder make it difficult to understand the rheological behavior of PMA in the aging process. The present study was meant to investigate the rheological behavior of various PMAs before and after aging (Rolling Thin Film Oven Test (RTFOT) and Pressure Aging Vessel (PAV)) by using rheological master curves in combination with Gel Permeation Chromatography (GPC). The GPC test was performed to obtain the average molecular weight (Mw) of the polymer and distribution of asphaltenes and maltenes.
The properties of chemical and rheological were analyzed comprehensively and the results indicated that the phase angle (δ) is more sensitive to asphalt composition (sulfur contents, polymer and base binder characteristic) than the complex shear modulus. Besides, the δ shape can strongly reflect the differences between the rheological responses of the modified asphalts under the different aging conditions. A plateau would occur if the SBS network was formed. Thus the δ shape of SBS modified asphalt will be closer to that of base binder when SBS structure was completely destroyed. Although the degradation of polymer became severer when sulfur was added, sulfur can promote the formation of three-dimensional structures of styrene–butadiene–styrene (SBS) and improve the rheological property of aged PMAs.
In this paper, fatigue progressive damage of fibre-reinforced composite is modelled by the present fatigue model, in which the fatigue damage incorporates two parts of the delamination and in-plane ...damage. The in-plane fatigue life is determined by the method of fatigue master curves. Further, Hashin and cohesive fatigue failure criteria are adopted for the determination of in-plane and delamination failure initiation, respectively. The fatigue master curve successfully predicts the fatigue life of fiber-reinforced composite with arbitrary layup sequence under fatigue loading of arbitrary stress ratio. Moreover, the delamination of interlayer subjected to arbitrary stress ratio is simulated based on the modified cohesive element. Finally, the proposed fatigue finite element model shows good agreements with the experimental data of notched glass fibre-reinforced plastic (GFRP) composite laminate and carbon fibre-reinforced plastic (CFRP) composite bolted joints.
•Fatigue life of composite is predicted by the master fatigue curves.•Interlayer damage under any stress ratios is modelled by modified cohesive law.•Progressive fatigue damage is modelled by the proposed model.
•An environmental friendly use of tung oil is introduced.•Physical, rheological properties, and functional groups of asphalt are conducted.•Tung oil could be a potential rejuvenating agent for aged ...asphalts.
One of the most effective measures to utilize abundant reclaimed asphalt pavement (RAP) materials, generated by the maintenance and reconstruction of asphalt pavements, is to employ rejuvenating agents. This study recognized tung oil as a rejuvenating agent and four different tung oils (2%, 4%, 6%, 8%, by weight.) blended with aged asphalts were carried out to assess the effect of tung oil on the performance and characteristic functional groups of Pen70 aged asphalt and SBS modified aged asphalt. Desired contents of tung oil were decided preliminarily by conventional property tests involving penetration, softening point, ductility, and rotational viscosity. Afterward, dynamic shear rheometer (DSR) tests including temperature sweep and frequency sweep and bending beam rheometer (BBR) tests were conducted, and Fourier transform infrared spectroscopy (FTIR) tests were implemented to analyze rheological properties and characteristic functional groups of original asphalt, aged asphalt and rejuvenated asphalt, respectively. Experimental results indicated that the addition of tung oil could enormously ameliorate the flexibility of aged asphalt, and suitable contents of tung oil can ensure the high-temperature performances of rejuvenated asphalts. Meanwhile, rejuvenated asphalt performed a better low-temperature cracking resistance than that of virgin asphalt from the test results of BBR. The stiffness of rejuvenated asphalts concluded by master curves is even higher than their corresponding virgin asphalts due to suffering aging, meaning they have lower temperature sensitivity. Also, Carbonyl and sulfoxide index of the Pen70 aged asphalt could be effectively abated by mixing with tung oil, but the existence of tung oil may interfere the test results of FTIR of SBS modified aged asphalt.
•Bio-asphalts prepared with different dosages of bio-oil extracted from sawdust were studied.•The influence of short-term aging condition on the rheological properties of bio-asphalt was ...analyzed.•The rutting factor master curves of bio-asphalt based binders were developed.•Incorporations of bio-oil into the SBS modified asphalt has greatly increased the rutting factor.
Bio-asphalt is a binding agent that is made of bio-oil and petroleum asphalt, or bio-oil modified with incorporations of some other additives under certain conditions. This study was carried out to evaluate the properties of bio-asphalt binder-based in terms of the value of complex shear modulus (G∗) and the phase angle (δ) tested by dynamic shear rheometer (DSR). Four bio-oil dosages of 5, 10, 15, and 20% based on the weight of asphalt (S100) were used to alter the SBS-modified binder. Whereby, the SBS content is approximately 1% of the weight of the virgin asphalt. The complex shear modulus and frequencies of virgin and short-term aged binders were tested. The master curves of rutting factor (G∗/sinδ) of different bio-asphalt were then generated to survey its rheological properties in a broad range of frequencies and temperatures. Based on the results, it was found that the addition of bio-oil extracted from sawdust has significantly increased the complex shear modulus of asphalt binder at the same frequency conditions after going through rolling thin film oven (RTFO), which is desirable for rutting prevention of asphalt mixtures. The rheological properties of bio-binders are more susceptible to the RTFO aging condition compared to the reference binder. The master curve of rutting factor of bio-binder indicated that the rutting factor of bio-asphalt increased with the increase of frequency before and after RTFO. Additionally, incorporations of bio-oil into the SBS modified asphalt, has greatly increased the rutting factor (G∗/sinδ) after RTFO, regardless of the loading frequency. However, the degree of enhancement was dominated by the percentage of bio-oil and aging condition.
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