Frequency Sweep Tests Research Articles

Enhanced Induction Heating and Self-Healing Properties of Steel Slag Powder Based Asphalt and Asphalt Mixture under Microwave Irradiation.

This paper aims to study the application feasibility of steel slag powder (SSP) in replacing limestone powder (LP) to enhance the heat release and self-healing properties of asphalt and an asphalt mixture. First, the microwave-heating characteristics of SSP and LP asphalt mortar were analyzed, and the differences in the microstructure and chemical composition between SSP and LP were compared. Secondly, through the DSR frequency sweep test, the optimal healing temperature of the two asphalt mortars was determined. Finally, asphalt mixtures with different SSP contents were prepared by replacing part of LP in the mixture in a gradation with SSP. Under microwave radiation, the temperature distribution of the mixture was explored, and the self-healing properties and factors affecting the healing were analyzed. Results demonstrated that there are metal oxides with high electromagnetic parameters such as Fe2O3 and CaO in SSP, therefore, asphalt and a mixture containing SSP were seen to have excellent microwave absorption capacity. The healing temperature of the two kinds of asphalt mortar was between ~50 °C and 60 °C. Under microwave radiation, the temperature of the asphalt mixture increased with the increase in SSP content, and the temperature difference decreased with the increase in SSP content. Asphalt mixtures with an LP content of 30%, 40%, 50%, 60%, and 70% replaced by SSP increased the healing index by 8.7%, 17.3%, 22.1%, 26.9%, and 27.7% compared with conventional asphalt mixtures. Temperature is the most important factor affecting the healing behavior of the asphalt mixture. With the increase in the damage times of the asphalt mixture, the overall healing index of the asphalt mixture showed a downward trend. However, the healing index of an asphalt mixture containing SSP can still be maintained at more than 50% after repeated mechanical damage.

Interaction, rheological and physicochemical properties of emulsified asphalt binders with direct coal liquefaction residue based geopolymers

The use of solid waste and low-cost gel materials to replace or reduce the use of ordinary Portl and cement (OPC) in emulsified asphalt (EA) binder has positive significance for the comprehensive energy consumption and economic cost of cold mix asphalt (CMA) pavement. The proposed study investigates the interaction, rheological and physicochemical properties of emulsified asphalt (EA) with direct coal liquefaction residue based geopolymers (DG) by fluorescence microscopy tests, the pH test, asphalt conventional tests, dynamic shear rheological test (DSR), and Fourier transform infrared spectroscopy test (FTIR). The test results show that the reaction between DG mortar and EA particles was faster and more violent than that of OPC mortar, resulting in faster demulsification of EA. The added DG mortar increased the pH of the EA binder. Similar to OPC, DG decreased the penetration and ductility of EA evaporation residues, but increased its softening point. The addition of DG to EA changed the rheological properties of its evaporation residue, including complex modulus (G*) and phase angle (δ). Temperature sweep and frequency sweep test results show that DG was comparable to OPC in efficacy against EA residues, improving rutting resistance at the expense of fatigue performance. Complex modulus coefficient (ΔG∗) and complex viscosity coefficient (Δη∗) indicate that the interaction of EA-DG is stronger than that of EA-OPC. FTIR analysis showed that the interaction between DG and EA is linked as a chemical bond.

Rheological Characteristics of Starch-Based Biodegradable Blends.

Thermoplastic starch was blended with commercially available biodegradable polyesters of poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) for its improved performance and processability. The morphology and elemental composition of these biodegradable polymer blends were observed by scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively, while their thermal properties were analyzed using thermogravimetric analysis and differential thermal calorimetry. For rheological analysis, the steady shear and dynamic oscillation tests of three samples at various temperatures were investigated using a rotational rheometer. All three samples exhibited significant shear thinning at all measured temperatures, and their shear viscosity behavior was plotted using the Carreau model. The frequency sweep tests showed that the thermoplastic starch sample exhibited a solid state at all temperatures tested, whereas both starch/PBAT and starch/PBAT/PLA blend samples exhibited viscoelastic liquid behavior after the melting temperature such that their loss modulus at low frequencies was greater than the storage modulus, and inversion occurred at high frequencies (storage modulus > loss modulus).

Investigating the Performance of Co [AM-AMPS-MALEIC-AAC]/ PEI-MBA Nanocomposite Hydrogel in Sand Control from Oil Reservoirs

Sand production is one of the major challenges in oil and gas production from sandstone reservoirs. Production losses, formation damage, corrosion, and equipment failure are all consequences of sand production. Various mechanical and chemical methods are used to control sand production. One of the most efficient chemical methods is the injection of hydrogels, but its application has been constrained by the hydrogels' weak stability in the harsh conditions of the reservoir. A Co [AMAMPS-MALEIC-AAC]/PEI-MBA nanocomposite hydrogel with superior viscoelastic properties and double crosslinking was developed and synthesized to overcome these restrictions. Swelling, rheology, and morphology tests were utilized to predict the produced nanocomposite's effectiveness and performance in the harsh Iranian reservoirs. According to the obtained results, at ambient temperature (25°C, during injection) and reservoir temperature (90°C, placed in a porous medium), in distilled water, the maximum swelling ratio was 8.5 and 94, and in formation water, the maximum swelling ratio was 5.4 and 10.8, respectively. The X-ray diffraction test findings show that the nanoparticles are uniformly distributed throughout the structure. Also, according to the results of the thermal strength test, the sample’s thermal stability up to 90°C was confirmed with less than 0.6 wt% degradation. The results of the strain sweep, frequency sweep and stress-strain tests demonstrate the existence of a robust, three-dimensional, and viscoelastic structure up to a strain of 100% and a frequency of 100 Hz. In the strain sweep test with a constant frequency of 1 Hz, the maximum storage modulus was reported as 27,000 Pa, and in the frequency sweep test with a constant strain of 1%, 18,000 Pascals were reported. The stress-strain test revealed that the ultimate tensile strength of the synthesized material was 4630 pascals. These characteristics make the aforementioned nanocomposite hydrogel ideal for usage in porous media.

Characterisation of Acrylonitrile Styrene Acrylate Modified Asphalt Cement with Nano Iron Oxide and Nano Silica Particles

The current study investigated the physical properties and rheological characteristics of asphalt cement (AC) modified by nano ironoxide (Fe3O4) and nano silica (SiO2) particles. Seven different blends including base AC, Acrylete-StyreneAcrylonitrile (ASA)/ Nanosilica (Si) and ASA/ Nanoironoxide (Fe) were the subject of experimental investigations. ASA was used at 5% for all modified blends while the nanomaterials were blended in 3, 5 and 7% concentrations by the weight of AC. Temperature susceptibility, rotational viscosity (RV) and storage stability for the base and polymer nanocomposite modified asphalt cement (PNCAC) were evaluated by the physical testing procedures while the frequency sweep test and the multiple stress creep recovery (MSCR) tests were conducted using a dynamic shear rheometer. The results showed that, the viscoelastic properties of the ASA/Si and ASA/Fe modified binders were improved when subjected to a range of temperatures and loading conditions. ASA/Fe composite modified AC demonstrated superior high temperature performance characteristics while ASA/Si composite modified AC although presented less significant improvement at the high temperature conditions, it was also able to improve the intermediate temperature fatigue resistance of asphalt more than the ASA/Fe composite modified AC. The optimum concentration of additives were found to be 3 and 5% for the ASA/Fe and ASA/Si modified AC respectively. Further addition of nanomaterials beyond the abovementioned concentrations resulted in degradation of the enhancement in physical and rheological properties of PNCAC, which was associated to the occurrence of agglomeration of nanoparticles and phase separation between the polymer-nanomaterial-asphalt matrix.

Sandwich meta-panels for vibration and explosion attenuation: Manufacturing, testing, and analyzing

In this research, composite sandwich meta-panels were designed, made and tested. The vibration and explosion attenuation effects of the meta-panel were revealed by frequency sweep tests, in-field explosion experiments, and finite element modeling (FEM). Meta-panel theory was also applied to predict the dynamic behavior. The local resonance metamaterial panel shows extraordinary vibration attenuation and explosion mitigation effects. The bandwidth of the meta-panel can reach 300 Hz, and the peak displacement can be reduced to 70% or less of that of the ordinary sandwich panel. The peak strain of the facesheet is reduced as well. The research provides an experimental basis for the application of metamaterials in protective buildings.

Investigation of the Rheological Properties of Asphalt Binders Modified with Nanomaterial

This study examined the effects of the Aerosil 150 addition on the rheological characteristics of bituminous binders at various temperatures. In the study, a frequency sweep test was applied to determine the rheological properties of pure binders and binders with 2%, 4% and 6% Aerosil 150 additives. Unaged binders were subjected to the frequency sweep test using a Bohlin DSR rheometer at test temperatures ranging from 40°C to 80°C (increasing by 10°C). The results showed that adding Aerosil 150 additive to the pure binder raised the binder's complex modulus (G*) values while decreasing the phase angle (δ) values. At 40 °C 0.1 Hz frequency, 2%, 4% and 6% Aerosil 150 doped binders gave G* values 1.52, 2.02 and 3 times higher than pure binder, respectively. The same ratio is 1.31, 1.54 and 1.99 times at 5 Hz frequency and 1.28, 1.47 and 1.82 times at 10 Hz frequency. At the same temperature, as the frequency value increases, the binders' complex modulus values approach each other. When the phase angle values at 40°C were examined, the 2%, 4%, and 6% Aerosil 150 modified binders, when compared to pure binder at 0.1 Hz frequency, yielded 2.75°C, 5.56°C, and 9.17°C lower phase angle values, respectively. This decrease is 3.19, 5.04 and 7.33 °C at 5 Hz frequency and 3.09, 4.84 and 6.76 °C at 10 Hz frequency. This shows that at various frequencies, the modified binder behaves more adaptably than the pure binder. The fact that the binder has a low δ value against a high G* value indicates that it will exhibit more flexible behavior. It was discovered as a result that Aeresil 150 modified binders performed better in terms of rheological qualities than pure binders.

Chitosan Hydrogels Cross-Linked with Trimesic Acid for the Delivery of 5-Fluorouracil in Cancer Therapy.

Chitosan exhibits unique properties making it a suitable material for drug delivery. Considering the rising popularity of hydrogels in this field, this work offers a comprehensive study of hydrogels constituted by chitosan and cross-linked with 1,3,5-benzene tricarboxylic acid (BTC; also known as trimesic acid). Hydrogels were prepared by cross-linking chitosan with BTC in different concentrations. The nature of the gels was studied through oscillatory amplitude strain and frequency sweep tests within the linear viscoelastic region (LVE) limit. The flow curves of the gels revealed shear thinning behavior. High G' values imply strong cross-linking with improved stability. The rheological tests revealed that the strength of the hydrogel network increased with the cross-linking degree. Hardness, cohesiveness, adhesiveness, compressibility, and elasticity of the gels were determined using a texture analyzer. The scanning electron microscopy (SEM) data of the cross-linked hydrogels showed distinctive pores with a pore size increasing according to increasing concentrations (pore size range between 3-18 µm). Computational analysis was performed by docking simulations between chitosan and BTC. Drug release studies employing 5-fluorouracil (5-FU) yielded a more sustained release profile with 35 to 50% release among the formulations studied in a 3 h period. Overall, this work demonstrated that the presence of BTC as cross-linker leads to satisfactory mechanical properties of the chitosan hydrogel, suggesting potential applications in the sustained release of cancer therapeutics.

Evaluation of the effects of asphalt binder aging degree on the curing, compatibility, and mechanical behaviors of epoxy asphalt binders

The application of epoxy asphalt binder in hot mix plant recycling for reclaimed asphalt pavement (RAP) can significantly increase the utilization rate of waste material on the premise of ensuring the service quality of the asphalt pavement. However, the development of epoxy asphalt binder modified RAP is hindered by the limited understanding of the effect of aging degree and types variability of asphalt binder in RAP on the properties of epoxy asphalt binder. Therefore, short-, long- and ultra-long- term aging tests of base asphalt and SBS modified asphalt binder were conducted through rolling thin film oven (RTFO), pressure aging vessel (20 h and 40 h) tests to obtain the asphalt binders with different aging extent, and then the binders were mixed with two epoxy systems to prepare epoxy asphalt binders, respectively. Next, the effects of asphalt binders aging degree on curing, compatibility, and mechanical behaviors characteristics of epoxy asphalt binders were investigated from chemical, microscopic, mechanical, and rheological perspectives based on Brookfield viscosity, Fourier transform infrared (FTIR), laser confocal fluorescence microscopy (LSCM), Shore hardness, direct tensile, strain sweep, and frequency sweep tests. The viscosity results indicated that a higher asphalt binder aging degree brought about a faster increase in the viscosity of epoxy asphalt binders. The construction allowable time of type-A epoxy asphalt binder of at least 3.5 h was higher than that of type-B. The conversion degree model constructed with the 917 cm−1 peak area as a parameter showed that the epoxy asphalt binder prepared by the asphalt binder with a more severe aging degree presented a higher conversion degree within the same curing time since the reaction space between epoxy and curing agent reactive groups was compressed by aggregated aged asphalt binder. The LSCM and Shore hardness results suggested that the aging asphalt binders induced the phase separation between asphalt and epoxy resin. With the asphalt binders aging, the distribution of asphalt phase in the epoxy system changed from black dots (12–15 um) to island-shaped structures (50–98 um), and eventually transferred a neuron-shaped network structure to connect island-shaped synaptosomes to block the continuity of three-dimensional network structure of epoxy resin. The rheological tests showed that the linear viscoelastic (LEV) region of the epoxy asphalt binders changed with the asphalt binders aging degree, and a shear strain of 0.01% ensured that specimens was within the LEV region. The effects of asphalt binders aging degree on the complex modulus and phase angle master curves of type-A epoxy asphalt binders mainly reflected the low frequency region (10−4 to 10−1 Hz), while the effects on type-B epoxy asphalt binders were in the whole frequency range (10−4 to 103 Hz).

Ethyl cellulose/hydroxypropyl methyl cellulose‐based oleogel shortening: Effect on batter rheology and physical properties of sponge cake

AbstractThis study attempts to fill the gap in ongoing research on the design, optimization, and characterization of ethyl cellulose/hydroxypropyl methyl cellulose‐based (EC/HPMC‐based) low‐saturated oleogel‐shortenings by examining their functional effects on physicochemical, and rheological properties in the cupcake and its batter. Thus, the commercial shortening was completely replaced with the oleogel‐shortenings in the cake formulation and, then, characteristics of the batter (including specific gravity, emulsion stability, and rheological properties), and cake samples (specific volume, moisture content, and texture properties) were evaluated and compared with each other and the control samples (containing commercial‐shortening). In short, the EC‐based‐ and EC/HPMC‐based‐oleogel‐shortenings‐batters had more specific gravity and emulsion stability than the control‐batter. Liner viscoelastic rang in EC/HPMC‐based‐oleogel‐shortenings‐batter, EC‐based‐oleogel‐shortenings‐batter, and control‐batter was 0.212%, 0.159%, and 0.195%, respectively. EC/HPMC‐based‐oleogel‐shortenings‐batter had a more viscoelastic behavior than EC‐based‐oleogel‐shortening‐batter after the control‐batter (p < 0.05). The results of frequency sweep and dynamic shear tests indicated a higher similarity of the rheological behavior of the EC/HPMC‐based‐oleogel‐shortening‐batter with the control‐batter. The results of moisture content and texture profile analysis of the cake samples indicated a slower staling in the oleogel‐shortenings containing samples, especially EC/HPMC‐based‐oleogel‐shortening type.

Restoration of physical properties on an aged crumb rubber modified bitumen adding a bio-based recycling agent

Reclaimed asphalt pavement (RAP) is a popular practice in the pavement industry due to environmental and economic benefits. But, RAP must be processed and treated before being reused in new pavements for preventing premature failures. A widely adopted strategy consists of adding recycling agents, and specifically rejuvenators, to mitigate the aging of the RAP binder. From the circular economy perspective, also crumb rubber (CR) from end-of-life tyres have been used to prepare binders with enhanced properties. The actual possibility of using the RAP derived from removed and/or reprocessed pavements containing CR particles (CR-RAP) for the formulation of new suitable mixtures is still a little-explored topic. Moreover, the available rejuvenators tailored on RAP have not yet evidence of effectiveness in producing asphalt mixtures containing CR-RAP. For this purpose, unaged, aged and rejuvenated blends with and without CR were studied through a rheological characterisation to evaluate the potential restoration of their physical properties when a bio-based recycling agent is added. The results of viscosity, frequency sweep, creep-recovery and multiple stress creep recovery (MSCR) tests have highlighted on the one hand the significant contribution of CR in reducing the accelerated aging effects of the binder, on the hand the effectiveness of the rejuvenator in restoring, more clearly at low temperatures, the rheological behaviour of the binders (above all for CRMB) similar to the unaged condition.

A framework for the analysis of damage and healing viscoelastic behaviour of asphalt binders

This paper aims to develop a framework for characterizing damage and healing viscoelastic behaviour of asphalt binders. The framework is based on modifying the 2S2P1D (two springs, two parabolic elements, and one dashpot) viscoelastic model such that the evolution of the exponent ‘k’ of the parabolic creep function is associated with damage and healing behaviours. The model efficacy is corroborated through the analysis of viscoelastic response, damage, and healing of four asphalt binders (i.e. one unmodified asphalt and three other asphalts modified using low-density polyethylene and various additives.) These binders were subjected to strain sweep tests to determine their linear viscoelastic strain limit. In addition, frequency sweep tests at several temperatures were conducted to obtain binder linear viscoelastic parameters. Then, the binders were subjected to strain-controlled, cyclic progressive damage tests (continuous loading) as well as cyclic damage-healing tests (i.e. cyclic loading with rest periods). The test data were analysed to obtain the storage and loss moduli as functions of loading cycles, and they were modelled using the modified version of the 2S2P1D model. The exponent of the parabolic creep element ‘k’ was formulated using a hyperbolic cosine function that quantifies the deviation from the linear viscoelastic response during damage and healing. The results showed that the ‘k’ function was suitable to quantify the damage and healing responses of the asphalt binders at the test conditions. Furthermore, the parameters in the ‘k’ hyperbolic cosine function were used to create a plot for classifying binders based on their damage and healing characteristics.

Waste Silt as Filler in Hot Mix Asphalt: A Laboratory Characterization

Several studies aimed to improve both the performance and environmental impact of asphalt pavements using waste and recycled materials as fillers. This study focused on the effect of untreated and thermally treated silt as a filler in hot mix asphalt (HMA). The silt used in the study was a byproduct from a local aggregate production plant in Bologna, Italy. Mineral and chemical analyses revealed that the waste silt required thermal treatment at 750 °C for 2 h. The study compared the use of calcined silt, untreated silt, and a common limestone filler in the production of asphalt mastics and HMA specimens. The rheological properties of the mastics were analyzed using frequency sweep and multiple stress creep recovery tests. The physical and mechanical characteristics of the HMAs were evaluated through the air voids content, Marshall stability and indirect tensile strength tests. Additionally, the water susceptibility and thermal sensitivity of the HMAs were evaluated through the indirect tensile strength ratio and indirect tensile stiffness modulus at different testing temperatures. The results showed that the addition of calcined silt had no significant effect on the rheological properties of the mastic or the optimal binder content. However, the samples produced with thermally treated silt showed the highest stiffness and resistance to rutting compared with the other samples. On the other hand, the addition of untreated silt slightly decreased the stiffness value of the samples. In conclusion, the use of waste silt as a filler has potential as a sustainable and eco-friendly solution for HMAs.

Impact of Laboratory Long-Term Aging Procedures on Intermediate-Temperature Behavior of Asphalt Binders in Asphalt Fine Aggregate Matrix Mixtures

The durability of asphalt mixtures and flexible pavements are closely related to the properties of the asphalt fine aggregate matrix (FAM) with aging. However, there are still no uniform aging procedures specified for laboratory-prepared FAM. In this study, the intermediate-temperature behavior of FAM under various accelerated aging procedures was investigated at the binder scale to reveal the influence of the FAM aging. Three different long-term aging procedures were considered, including loose mixes aging (95°C and 135°C) and pressure aging vessel (PAV) protocols. Frequency sweep test and linear amplitude sweep (LAS) test were carried out on binders extracted from aged FAMs. Rheological tests were also performed on corresponding binders with standard PAV procedure to show the impact of FAM during the aging process. Moreover, an aging kinetics model was put forward to qualify the linear rheological property evolutions for fast and constant aging reaction stages under various aging conditions. The results show that 135°C loose FAM mixes aging significantly reduces the fatigue performance of styrene-butadiene-styrene (SBS) modified binder, and employing 95°C loose mixes aging and PAV aging procedures can avoid this adverse effect. Moreover, to match the aging degree of asphalt and FAM, an aging duration more than 40 h is recommended.

Laboratory and Full-Scale Testbed Study in the Feasibility of Styrene-Butadiene-Styrene Asphalt Pavement Having Epoxy Resin and Crumb Rubber Powder

Conventional asphalt concrete pavements have deteriorated rapidly due to the current increased traffic and extreme climate impacts. In addition to the upgrading in the construction quality, there is an urgent need to expand the utilization of modified asphalt binders to improve road capacity and traffic safety. The proposed research aims to combine epoxy resin (ER) and crumb rubber powder (CRP) contents into conventional Styrene-butadiene-styrene (SBS)-modified asphalt binder to not only reduce the consumption of normal asphalt binder but also promote the usage of recycled waste material in practice. To cope with this research objective, the ER and CRP were designed at 3% and 5% by weight of asphalt binder, respectively. Various laboratory tests were performed to evaluate the performance of modified mixtures (ERCRP), including the Frequency Sweep Test, Multiple Stressed Creep and Recovery, Dynamic Modulus, Semi-Circular Bending (SCB), and Cantabro Durability Tests. Additionally, an assessment of the modified asphalt concrete pavement via field testbed was conducted through Falling Weight Deflectometer and Ground Penetrating Radar. Overall, by adding the ER and CRP, the strain value of the control reference mix can be reduced up to 31.8% and 28.3% at MSCR 0.1 and 3.1 kPa, respectively. Additionally, the dynamic modulus of the ERCRP-modified samples was approximately 32,267 and 189 MPa, while the value of the reference mixture was 28,730 and 105 MPa at the highest and lowest frequency, respectively, indicating an enhancement under repeated loads. Regarding the SCB test results at 0 °C, the peak stress of the ERCRP-modified mixture was 4.75 MPa, while the value of the reference specimens was only 4.2 MPa, noticing the improved stress-bearing capacity. Based on a full-scale testbed, the FLWD elastic modulus of reinforced pavement shows a novel improvement (6.75%) compared with the control pavement, suggesting a potential application of ERCRP-modified asphalt binder for sustainable development purposes.

Rheological evolution mechanisms of asphalt binder and mastic under freeze-thaw cycles

Perennial freeze-thaw cycles have caused plenty of defects on asphalt pavements. To analyze the effect on asphalt binder and mastic under freeze-thaw cycles, the multiple stress creep recovery (MSCR) tests, frequency sweep tests, linear amplitude sweep (LAS) tests, and bending beam rheological (BBR) tests were performed first. The rheological property of asphalt binder and mastic was evaluated through the Burgers model, 2S2P1D (two springs, two parabolic elements, and one dashpot) model, Sigmoidal model, and viscoelastic continuum damage (VECD) theory. The Einstein coefficient and K.D.Ziegel−B−G∗ (K−B−G∗) model were adopted to investigate the asphalt binder-filler interaction subsequently. Finally, Fourier transform infrared spectroscopy (FTIR) test was conducted to analyze the variation of chemical composition of asphalt binder before and after freeze-thaw cycles. The results showed that as freeze-thaw cycle increased, the percent recovery of asphalt binder increased, and the non-recoverable creep compliance of asphalt binder decreased and that of asphalt mastic increased first but decreased. The rutting factor and fatigue factor of asphalt binder and mastic increased after freeze-thaw cycles. The asphalt mastic showed poorer fatigue resistance than asphalt binder at a given freeze-thaw cycle. The low-temperature stiffness of asphalt binder and mastic increased as freeze-thaw cycle increased. K−B−G∗ value showed that the asphalt binder-filler interaction damaged seriously after fifteen freeze-thaw cycles, and the Einstein coefficient decreased by 52.73% after twenty freeze-thaw cycles. The IS and IC indexes increased, and the IB index decreased after twenty freeze-thaw cycles. The design and construction of asphalt pavement in seasonal frozen regions may benefit from this study.

Application of high-intensity ultrasound to modify the rheological properties of a guamuchil Pithecellobium dulce (Roxb.) seed protein isolate

ABSTRACT In the present study, the application of high-intensity ultrasound (USon) on the rheological properties of guamuchil seed protein isolate (GPI) was evaluated. GPI dispersions (30% w/v) were subjected to USon treatments (20 kHz; 200, 400, and 600 W) for 15 and 30 min. Strain, frequency, and temperature sweep tests showed that the storage (G) and loss (G”) moduli increased, while loss tangent (Tan δ) decreased by USon. The results showed a dominance of G’ over G”, indicating the formation of a stronger and more elastic dispersion due to USon, especially at high power (600 W for 15 and 30 min). Compared to native GPI, the USon treatments that caused the largest decreases in apparent viscosity (ηapp ) and the most notable shear thinning behavior were at low (200 W) and high (600 W) power. The modification of the rheological characteristics of GPI by USon could be associated with structural changes, which modifies the inter and intramolecular interactions. The rheologically improved GPI by USon could represent an alternative to diversify its possible use as a new food ingredient.

Characterizing ZSV of SBS modified asphalt using shear rate sweep test and frequency sweep oscillation test

The Zero-shear viscosity (ZSV) of asphalt is frequently measured using shear rate sweep test (η) or frequency sweep test (η*), whose correlation is often established via the cox-merz rule. However, the applicability of cox-merz rule upon SBS modified asphalt (SBSMA) is still debatable. This study aims to characterize ZSV of SBSMA using both shear rate sweep test and frequency sweep test and examine the cox-merz rule for SBSMAs with different SBS contents. The testing temperature is fixed at 60 °C and to enlarge the η* testing frequency range, master curve is created based on a novel double sigmoidal model. Results indicate that cox-merz rule is valid for plain asphalt but not for SBSMA, and the deviation is more evident for highly modified SBSMA (the deviation increases from 0.8 % to 13.2 %). Based on Kramers-Kronig relations, SBSMA must be pure viscous (phase angle δ = 90°) to obtain a strict η* plateau for ZSV measurement, which is quite difficult because SBSMA can only be pure viscous above the SBS polymer glass transition temperature (100 °C). Therefore, it is theoretically impossible to obtain an SBSMA η* plateau at 60 °C that resembles the η plateau, hence the cox-merz rule fails. A η* Newtonian plateau was observed in the master curve, but it was obtained at temperatures higher than 100 °C and cannot be used for 60 °C ZSV measurement either. With reduced frequency, the η* master curve of SBSMA shows 4 stages including a “pseudo-plateau”. The pseudo-plateau should be treated with care and cannot be used for ZSV measurement.

Rheological Properties and Microscopic Characterization of Delayed Decay-Modified Asphalt Based on UV Ageing

For clarifying the applying feasibility of hindered amine light stabilizers in asphalt binder, two types of hindered amine light stabilizers were chosen as a UV ageing resistance modifier and the modified asphalt was prepared with a selected UV ageing resistance modifier. The ultraviolet aging testing method of asphalt materials was proposed for UV ageing behavior characterization. Under the condition of different frequencies, the impact of UV ageing resistance modifier on asphalt was investigated through using the frequency sweep test of DSR. Under the effect of ultraviolet aging, the variation of thermal properties of UV ageing resistance-modified asphalt was deeply analyzed by means of a temperature scanning test of DSR following the increase of temperature. The change law of the surface morphology of light stabilizer-modified asphalt was characterized by atomic force microscopy (AFM) dynamically with the UV aging time extension. The research results showed that the hindered amine light stabilizer could improve the high temperature performance of asphalt and achieve the UV aging behavior of asphalt materials effectively. Meanwhile, the corresponding reaction mechanism was explored at the microscopic level.

Design and test of a small high frequency ultrasonic cleaning transducer

In order to solve the problem of cleaning of complex surfaces and micro blind holes in industrial products, a small high frequency ultrasonic cleaning transducer was designed and tested. Firstly, the finite element model of the transducer was established, and the influence of structural parameters on the first order longitudinal vibration frequency was analyzed. By adjusting the structural parameters of the transducer, the first order longitudinal vibration frequency of the transducer was determined to be 58716hz.The harmonic response of the transducer was analyzed. The results showed that when the voltage amplitude applied on the piezoelectric ceramic sheet was 80V, the transducer produced resonance at 58716 Hz, and the end face of the front cover of the transducer produced an axial displacement of about 3.34 µm . The transducer was made according to the theoretical analysis results, and the frequency sweep test was carried out on the transducer. The theoretical analysis results were consistent with the test results, which showed that the designed small high frequency ultrasonic cleaning transducer could meet the requirements of high frequency cleaning.