Dynamic Shear Rheometer Test Research Articles

Use of Hydrated Ladle Furnace Slag as a filler substitute in asphalt mastics: Rheological analysis of filler/bitumen interaction

The increase in industrial activity and societal demand has made the reuse and recovery of industrial waste and by-products a topic of global importance. New technologies focused on the reuse of these materials open up the possibility of promoting a sustainable circular economy in the industrial sector. Ladle furnace slag (LFS) is an industrial waste generated during steel refining, through a process of deoxidation and desulfurization of the material while it is in a liquid state in its second refining stage. This process generates large quantities of LFS without being used on a large scale, and most of it is destined for stockpile fields, producing an environmental and economic impact. The present research is based on the incorporation of Hydrated Ladle Furnace Slag (LFSh) into asphalt mastics to evaluate its viscoelastic behaviour using the Dynamic Shear Rheometer test (DSR-test). The incorporation of this industrial by-product generates an increased stiffness of the asphalt mastic, compared to a conventional mastic made with limestone. This increase in stiffness is greater in large dosages of LFSh filler, causing an inferior performance to limestone mastic at low temperatures in relation to what was demonstrated in the Linear Amplitude Sweep test (LAS) and Binder Yield Energy Test (BYET). The results obtained in the Multiple Stress Creep Recovery test (MSCR) show that the incorporation of LFSh filler is appropriate for warm conditions. Furthermore, the filler/bitumen ratio of 0,75 provides an increase in recoverability (R) of 24.17% over limestone mastic asphalt at a temperature of 70 °C and a load of 3.2 kPa, and a significant loss of lower integrity at low temperatures (25 °C).

Experimental Investigation of High Temperature Behaviour of an Asphalt Binder Modified with Laval University Silica Based on Multiple Stress Creep and Recovery Test

For experimental investigation of the high temperature behaviour of an asphalt binder modified with Laval university silica (LUS-1) nanostructured particle, four different asphalt binders were produced using a mixture of 2, 4, 6 and 8 wt% of this additive and a neat bitumen at 170 °C. The neat bitumen was yielded from crude oil refining and had a penetration grade of 85–100. After a 20 min vibration, the produced mixtures were mechanically mixed for 30 min in a high-shear homogenizer mixer with an angular velocity of 4500 rpm. Then, the modified binders and neat bitumen were subjected to multiple stress creep and recovery (MSCR) test, after the aging process in rolling thin film oven (RTFOT) test. The results of this study, which were in agreement with the results of the dynamic shear rheometer (DSR) test, indicated that LUS-1 could improve the high temperature behaviour of binders. The greatest improvement occurred using 4 wt% of LUS-1, where this improvement was more pronounced at high stress levels. Elevating the levels of stress and temperature led to diminished traffic grade and more viscous behaviour in asphalt binders modified with LUS-1.

Preparation and characterization of lignin grafted layered double hydroxides for sustainable service of bitumen under ultraviolet light

Bitumen could emerge the degradation of performance under ultraviolet (UV) light easily, then the bituminous pavement would have to be repaired and even reconstructed for safety, causing environmental pollution and energy consumption. Therefore, it is crucial to raise bituminous anti-UV aging property so that the service life of bitumen could be increased memorably, which is beneficial to environmental protection and sustainable development. Lignin grafted layered double hydroxides (LG-g-LDHs) were prepared successfully through covalent bonding with diphenyl-methane-diisocyanate (MDI), and were characterized by Fourier transform infrared (FTIR) spectrometer, scanning electron microscopy (SEM) contact angle tester and ultraviolet and visible (UV–vis) spectroscopy. Then LG-g-LDHs were used for modifying bitumen, the effects on anti-UV aging properties were researched by physical properties, four components analysis, FTIR and dynamic shear rheometer (DSR) test. The results showed that LG-g-LDHs were prepared and represented a stable cross-linked structure, then they had a combined effect of chemically absorbing and physically reflecting UV light owing to the multi-layered and benzene ring structure. Due to the introduction of lignin, the compatibility between LDHs and bitumen could be improved. After aging, the properties including physical properties and rheological behaviors of bitumen decreased and colloidal stability declined. Compared with LDH, LG-g-LDHs represented better inhibitory action in performance deterioration and colloidal stability of bitumen, which indicated that LG-g-LDHs could strengthen bituminous anti-UV aging properties for sustainable service of bitumen.

Pseudo energy-based crack initiation criterion for asphalt-filler composite system under a fatigue shear load

Fatigue crack initiation is the precondition of fatigue crack propagation and failure of asphalt materials. To trace the fatigue crack initiation of asphalt-filler composite system (AFCS) under a fatigue shear load, a pseudo energy-based crack initiation criterion is established by Griffith’ theory and validated by surface energy tests and molecular dynamics simulation in this study. Nondestructive and destructive dynamic shear rheometer tests are performed on the AFCSs with two different volumetric contents of limestone filler (10% and 27%) at different temperatures (15 °C, 20 °C and 25 °C) and one frequency (10 Hz). Surface energy tests of the asphalt binder and molecular dynamics simulations of interface debonding between the asphalt binder and limestone mineral at 15 °C, 20 °C and 25 °C are carried out. Results show that the pseudo energy-based crack initiation criterion of the AFCS can be modeled by dissipated pseudo strain energy, recoverable pseudo strain energy, initial crack size and total surface energy of the material. The interface debonding process between the asphalt binder and filler involves a large proportion of cohesive debonding (68.093%, 71.733%, 84.288% at 15 °C, 20 °C, 25 °C, respectively), and the proportion increases with temperature. The total surface energies of AFCS predicted by the pseudo energy-based crack initiation criterion match with that obtained from the surface energy testing results and the molecular dynamics simulations.

Research on Performance of SBS-PPA and SBR-PPA Compound Modified Asphalts.

Although several studies indicated that the addition of Styrene-Butadiene-Styrene (SBS) and Styrene-Butadiene Rubber (SBR) bring a lot of benefits on properties of asphalt binders, high production costs and poor storage stability confine the manufacture of better modified asphalt. To reduce the production costs, polyphosphoric acid (PPA) was applied to prepare better compound modified asphalt binders. In this research, five PPA (0.5%, 0.75%, 1.0%, 1.25% and 1.5%) and two SBR/SBS (4% and 6%) concentrations were selected. Dynamic shear rheometer (DSR) and Bending Beam Rheometer (BBR) tests were performed to evaluate the rheological properties of the compound modified asphalt. Rolling Thin Film Oven (RTFO) test was performed to evaluate the aging properties of the compound modified asphalts. The results indicate that SBS/SBR modified asphalts with the addition of PPA show better high-temperature properties significantly, the ability of asphalt to resist rutting is improved, and the elastic recovery is increased. However, the low-temperature properties of the compound modified asphalts are degraded by increasing the creep stiffness (S) and decreasing the creep rate (m). At the same time, RTFO tests results show that PPA was less prone to oxidation to improve the anti-aging ability of modified asphalts. Overall, the combination of 4% SBS and 0.75–1.0% PPA, the combination of 4% SBR and 0.5–0.75% PPA is recommended based on a comprehensive analysis of the performance of compound modified asphalt, respectively, which can be equivalent to 6% SBS/SBR modified asphalt with high-temperature properties, low-temperature properties, temperature sensitivity and aging properties.

A Comparison on Physical and Rheological Properties of Three Different Waste Plastic-Modified Bitumen

This study aims to investigate the effect and the possibility of using waste plastic as a sustainable cost-effective polymer to modify bitumen binders. Different types of waste plastic have been used in this modification, including polyethylene terephthalate (PET), high-density polyethylene (HDPE), and low-density polyethylene (LDPE). The modification targets the physical characteristics, rheological properties, and binders’ resistance to ageing. Both long- and short-term ageing are investigated to determine the durability and ageing resistance of the modified binder using rolling thin film oven tests (RTFOT) and pressure ageing vessels (PAVs). Penetration tests and dynamic shear rheometer (DSR) tests were conducted to investigate and evaluate the complex shear modulus, stiffness, elasticity, and viscous properties. The results show that 2% and 4% of HDPE and LDPE are recommended as ideal contents for good performance, as reflected by the penetration tests before and after ageing. However, higher contents, such as 6% and 8% HDPE and LDPE, are not significant in improving the stiffness, elasticity, and ageing resistance. Therefore, samples of 6–8% HDPE and LDPE are more vulnerable to permanent deformation. Furthermore, using waste PET exhibits obvious improvements in terms of the physical characteristics, rheological properties, stiffness, elasticity, and ageing resistance with up to 8% PET-modified bitumen. Based on the results, the ideal type and content is 6–8% PET waste plastic.

Synergistic effect of SBS copolymers and aromatic oil on the characteristics of asphalt binders and mixtures containing reclaimed asphalt pavement

Rejuvenators have been utilized to restore the physical and rheological properties of aged asphalt binders found in the reclaimed asphalt pavement (RAP). Also, the rejuvenators are utilized to enhance the cracking resistance of asphalt containing RAP. In addition, polymers have been efficiently applied to enhance the rutting performance of rejuvenated mixtures. The purpose of this study was to assess the influence of combining SBS copolymers and aromatic oil (AO) at the same time as a hybrid rejuvenator (HR) on the performance of high RAP asphalt binders and mixtures. HR is a mixture of 25% SBS and 75% AO. The properties of the rejuvenated binders were assessed by SARA (Saturates, Asphaltene, Resin, and Aromatics) fractions analysis, Fourier Transform Infrared Spectrum (FTIR), physical tests, high-temperature storage stability test, Dynamic Shear Rheometer (DSR) test, and Bending Beam Rheological (BBR) test. In addition, the mechanical behaviour of the rejuvenated mixtures was assessed using the Indirect Tensile Strength (ITS) test, moisture susceptibility test, resilient modulus test, and wheel tracking rutting test. The results showed that appropriate adjustment of the SARA fractions and SBS copolymer could improve the overall performance of mixtures and binders with high RAP content. However, it is asserted that a field investigation of this compound rejuvenator should be done to further analyze its influence on the long-term field behavior of high RAP mixtures.

Unlocking the Hidden Potential of Cosmetics Waste for Building Sustainable Green Pavements in the Future: A Case Study of Discarded Lipsticks.

This investigation is dedicated to unlocking the hidden potential of discarded cosmetics towards building green sustainable road pavements in the future. It is particularly aiming at exploring waste lipstick (WLS) as a high-quality functional additive for advanced asphalt mix technologies. To fuel this novel innovation, the effect of various WLS doses (e.g., 5, 10, and 15 wt.%) on the performance of base AP-5 asphalt cement was studied in detail. A wide array of cutting-edge analytical lab techniques was employed to inspect in-depth the physicochemical, microstructural, thermo-morphological, and rheological properties of resultant admixtures including: elemental analysis, Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thin-layer chromatography-flame ionization detection (TLC-FID), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), needle penetration, ring and ball softening point, Brookfield viscometer, ductility, and dynamic shear rheometer (DSR) tests. Unlike the unstable response of asphaltenes, the additive/artificial aging treatments increased the fraction of resins the most, and decreased that of aromatics; however, asphaltenes did not impair the saturates portion, according to Iatroscan research. FT-IR scan divulged that the WLS-asphalt interaction was physical rather than chemical. XRD diagnosis not only revealed an obvious correlation between the asphaltenes content and the fresh-binder crystallinity but also revealed the presence of fillers in the WLS, which may generate outstanding technical qualities to bituminous mixes. According to AFM/SEM analyses, the stepwise incorporation of WLS grew the magnitude of the “bee-shaped” microstructures and extended the roughness rate of unaged/aged binders. The prolonged consumption of the high thermal-stable additive caused a remarkable drop in the onset degradation and glass transition temperature of mixtures, thus enhancing their workability and low-temperature performance, according to TGA/DTGA/DSC data. The DSR and empirical rheological experiments demonstrated that the WLS could effectively lower the manufacturing and compaction temperatures of asphalt mixes and impart them with valuable anti-aging/fatigue-cracking assets. In a nutshell, the use of waste lipstick as an asphalt modifier is viable and cost-effective and could attenuate the pollution arisen from the beauty sector, while improving the performance of hot/warm asphalt mixes (HAM/WAM) and extending the service life of roadways.

Evaluation on the Performance of Hydraulic Bitumen Binders under High and Low Temperatures for Pumped Storage Power Station Projects.

The high and low-temperature performance of five hydraulic bitumen binders was evaluated using the dynamic shear rheometer (DSR) test, infrared spectrum test and direct tensile (DT) test. These hydraulic bitumen binders were respectively applied for several pumped storage power stations (PSPS) projects that were constructed or under construction. In order to relate the bitumen performance to the mixture performance, the slope flow test, three-point bending test and thermal stress restrained specimen test were carried out on hydraulic asphalt mixtures. The test results indicated the DSR rheological master curves can well distinguish the difference of each bitumen binder as well as the effect of polymer modification. Phase angle master curves, black diagrams and infrared spectra all indicated that several penetration-grade hydraulic bitumen binders were not virgin bitumen binders but were modified with relatively lower SBS polymer content when compared with traditional SBS-modified bitumen. When selecting the commonly used Karamay SG70 hydraulic bitumen as a reference, the normal SBS-modified bitumen was superior to other bitumen in terms of low- and high-temperature performance. Several slightly SBS-modified bitumen binders did not always show consistent results, which indicated that slightly modified bitumen may not really have the desired performance as expected. Therefore, SBS-modified bitumen will be more promising when dealing with extremely low or high temperatures. Bitumen performance was well compared with the mixture performance by using the bitumen creep, relaxation and tensile failure strain corresponding to the asphalt concrete slope flow, the maximum bending strain and the failure temperature, respectively. Compared with the traditional penetration, softening point and ductility test, it indicated that the DSR rheological test, creep test, direct tensile test and stress relaxation test can be used as more powerful tools for the characterization and optimization of hydraulic bitumen binders.

Coupled Effects of Gilsonite and Sasobit on Binder Properties: Rheological and Chemical Analysis

Experiences of highway agencies show that the costs of repairing rutting distresses are high. The common solution to overcome this issue is using a modified asphalt binder. The modifier enhances the asphalt binder’s rheological and physical properties but increases the production temperatures of asphalt pavement. Nevertheless, warm mix asphalt (WMA) production at temperatures lower than hot mix asphalt (HMA) could lead to lower aging of asphalt binders. In this study, the physical and rheological properties of modified asphalt binders with different contents of Gilsonite and their combination with Sasobit as a WMA agent were investigated. Accordingly, 5%, 9%, and 13% Gilsonite, as well as 3% Sasobit in combination with Gilsonite, were used to modify asphalt binders. Dynamic shear rheometer (DSR), rotational viscosity (RV), surface free energy (SFE), Fourier-transform infrared spectroscopy (FTIR), and some conventional tests (i.e., penetration grade, softening point, and storage stability) were conducted to evaluate the properties of the binders. The results of chemical analysis tests (i.e., SFE and FTIR) indicated that using Gilsonite and Sasobit as composite modifiers could further improve the thermomechanical properties. The DSR test results also showed that the Gilsonite and its combination with Sasobit improve the high-temperature performance of asphalt binders and, consequently, increase the rutting resistance. However, Gilsonite could raise the asphalt binder elasticity and showed better results when Sasobit was incorporated. In general, Gilsonite increased the asphalt binder stiffness, and consequently, it could reduce the workability and compactability of mixtures. Therefore, the use of Sasobit as a complement for Gilsonite reduces the viscosity of the asphalt binder and enhances the mixture workability. This could pave the way to use Gilsonite in WMA, resulting in more durable and sustainable asphalt mixtures.

Preparation and performance evaluation of surface-modified polyacrylonitrile fiber and SBS composite modified asphalt binder based on bionic hierarchy

In this study, polydopamine/polyethyleneimine (PDA/PEI) bionic coating and nano-silica were self-assembled on the surface of polyacrylonitrile (PAN) fiber to construct bionic multilevel hierarchical structures. The fiber composites were in turn used as secondary modifiers to prepare fiber reinforced styrene butadiene styrene modified asphalt binder (SBS@M-AB). Field emission scanning electron microscopy, energy dispersive spectroscopy, and atomic force microscopy analyses revealed rough surface of the modified fiber and successfully constructed a biomimetic multi-level hierarchical structure. These intriguing aspects are conducive to mitigating the local high stress of SBS@M-AB and achieving multi-scale mitigation of stress concentration, which in turn improves the performance of Mud-brick PAN fiber (MB-PAN) incorporated SBS@M-AB. Dynamic shear rheometer test showed that MB-PAN/SBS@M-AB exhibited better viscoelastic properties and deformation resistance than the pristine PAN/SBS@M-AB. TG test showed that the bionic multi-level hierarchical structure enhanced the interfacial properties of fiber materials which in turn boosted the thermal stability of MB-PAN/SBS@M-AB. The cone penetration analysis showed the much higher shear strength of MB-PAN/SBS@M-AB than the pristime SBS@M-AB. The results of this study are promising and challenging for designing modified asphalts with better thermal and mechanical performance for practical applications in construction and highway industries.

Asphalt Binder Testing at Low Temperature: Three-Point Bending Beam Test in Dynamic Shear Rheometer

A novel Three-Point Bending Beam Test (3-PBT) using a Dynamic Shear Rheometer (DSR) with linear drive motor is introduced for testing asphalt binder at low temperature conditions. This 3-PBT in DSR can be used as surrogate for Bending Beam Rheometer (BBR) tests. Advantages in comparison to BBR are that (i) 3-PBT works without harmful cooling medium ethanol, (ii) the amount of asphalt binder for testing is significantly lower (using material equivalent of 10% of BBR tests), (iii) a silicone rubber mold is used for specimen preparation instead of standard aluminum mold for BBR tests, which makes handling easier, and (iv) the loading protocol is more practical without applying contact load manually. The novel 3-PBT in DSR is presented with respect to preparation, installation, and conditioning of specimens, as well as to the loading protocol. Tests were conducted at temperatures of −10, −16, and −20°C. For the purpose of comparison to BBR tests, and of identifying most suitable testing conditions from alternative setups, a test series was run including 9 different asphalt binders. As to BBR tests, two different cooling media were used, i.e., ethanol and air. Finally, all test results obtained from DSR and BBR tests were analyzed in view of precision and correlation. DSR results correlated well with BBR results, while precision of 3-PBT in DSR was found to be satisfying.

High-Temperature Rheology Characteristics of Hard Petroleum Asphalt Used in China

Hard petroleum asphalt, which is a high modulus asphalt binder material, is used for improving asphalt pavement rutting distress. This property is attributed to the good high-temperature rheological characteristics of hard petroleum asphalt. The study investigates the performance of hard petroleum asphalt and Styrene-Butadiene-Styrene polymer modified asphalt (SBSPMA) based on three aspects: asphalt oil source, asphalt grade, and aging degree. The short-term and long-term aging of four hard petroleum asphalts and SBSPMA of comparative samples were measured using the rolling thin film oven test (RTFOT) and the pressure aging test (PAV). Firstly, the viscosity-temperature curve of hard petroleum asphalt was obtained using the Brookfield viscosity test at different temperatures combined with the improved REFUTAS formula. The complex shear modulus ( G ∗ ), phase angle (δ), and rutting factor ( G ∗ / sin δ ) of each asphalt sample were then measured by the dynamic shear rheometer test (DSR). Furthermore, the temperature sensitivity of each asphalt sample was calculated using the complex modulus index method (GTS). The compaction and paving temperature ranges of each asphalt were then confirmed. The results showed that the high-temperature rheological characteristics of hard petroleum asphalt were similar to those of SBSPMA. The temperature sensitivity of hard petroleum asphalt was basically the same as that of SBSPMA, while the influence of aging on the G ∗ of hard petroleum asphalt was greater than that of SBSPMA. In addition, the hard petroleum asphalt construction temperature was lower than that of SBSPMA.

Mechanical properties of asphalt concrete modified with carbon nanotubes (CNTs)

Three different percentages of carbon nanotubes (CNTs) (0.1%, 0.5%, and 1% by mass of asphalt cement) were used to modify conventional asphalt cement (60/70) in this study. Mechanical properties of modified asphalt cement and mixture were evaluated. Penetration grade, kinematic viscosity, softening point and dynamic shear rheometer test were measured to evaluate physical properties of modified asphalt cement. The results exhibited that modifying asphalt cement with CNTs decreased its penetration and increased its kinematic viscosity and softening point. Rutting parameter increased with CNTs at the given temperature for both unaged and RTFOT-aged samples. Marshall stability tests, low temperature cracking tests, indirect tensile tests and wheel tracking tests were conducted to assess the mechanical performance of modified hot asphalt mixture. The Marshall stability increased with CNTs but no significant difference at 0.5 and 1.0 wt%, while Marshall flow decreased with CNTs. The results of wheel tracking test showed that rut depth decreased by 45% upon adding 0.5% CNTs by weight of asphalt cement; also, this percentage of CNTs endowed improvement in low temperature cracking and indirect tensile strength of the asphalt concrete. This study underlines that adding CNTs into asphalt cement enhances the performance of asphalt concrete pavement in both hot and cold weather, which in turn prolongs the pavement’s service life and saves maintenance expenses.

Waste engine oil and polyphosphoric acid enhanced the sustainable self-healing of asphalt binder and its fatigue behavior

Asphalt self-healing capability is critical to the asphalt industry's sustainable development. The paper attempts to explore the feasibility of waste engine oil (WEO) and polyphosphoric acid (PPA) to enhance self-healing of asphalt binder and its fatigue behavior. The different proportion of WEO and PPA were mixed with asphalt to modify asphalt initially. Dynamic shear rheometer (DSR) test and linear amplitude sweep (LAS) test were adopted to establish the modulus master curve and evaluate fatigue behavior. With the aim of estimating the healing degree of asphalt binders, evaluating indicators consist of fatigue life recovery, modulus recovery and dissipated energy recovery were adopted based on fatigue-healing test. The phase state transition of asphalt binders related to temperature was determined by differential scanning calorimetry (DSC) test. Ultimately, to evaluate modification effect of different additives on asphalt binder comprehensively, radar chart method is employed. It can be concluded that the addition of PPA and WEO improves fatigue performance and self-healing of asphalt binder. As for additives with 2% PPA and 2% WEO, 1% PPA and 4% WEO, fatigue life in LAS predicted model presents extreme value, increasing by 1000% and 1150% than original asphalt respectively. The raise of anti-permanent deformation for asphalt modified by WEO/PPA can be attributed to the presence of PPA. Compared with original asphalt, a significant increase of fatigue life recovery, modulus recovery and dissipated energy recovery is observed at asphalt modified with 6% WEO regardless of PPA content. Additionally, the healing indicators increment of the original asphalt is larger than modified asphalt with the extension of the healing time. This is because most of damage of modified asphalt could recover at a relatively short time. Analysis of the DSC indicates that the two peak temperatures of original asphalt are lower than that of modified asphalt. It helps to improve self-healing and fatigue behavior of asphalt binder. Overall, a promising way to promote the sustainable development of asphalt industry is put forward.

Facile synthesis of polyethylene-modified asphalt by chain end-functionalization

Polyethylene (PE) is an inexpensive asphalt additive, the application of which provides a cost-effective way to improve the performance of asphalt pavements. However, the poor storage stability of PE-modified asphalt limits its large-scale application. The effective synthesis of stable PE-modified asphalt remains challenging. Here, we report the synthesis of storage-stable PE-modified asphalt using end-group functionalized PE. The low molecular weight NH2-terminated-PE (NPE) was synthesized and dispersed into asphalt, as confirmed by fluorescence microscopy. After 48 h in an oven at 163 °C, the modified asphalt sampled from top and bottom showed similar softening points, demonstrating great storage stability. Specifically, the difference of softening points is 1.1 °C and 0.4 °C for asphalt with 3 wt% and 5 wt% NPE addition, which exceeded most PE-modified asphalt in previous reports. The addition of NPE to asphalt also reduced the penetration and increased the low temperature ductility. Improved rheology of NPE-modified asphalt was illustrated by dynamic shear rheometer and stress creep recovery test. Our work has demonstrated that storage stability of PE-modified asphalt successfully enhanced by end-group functionalization of PE. With good storage stability, the NPE-modified asphalt would have potential application as pavements.

Effect of styrene-butadiene-styrene (SBS) on laboratory properties of low-density polyethylene (LDPE)/ethylene-vinyl acetate (EVA) compound modified asphalt

Waste plastic composed of polyethylene is one of the main factors of environmental pollution due to the slow degradation in nature, reuse waste materials to improve asphalt properties and relieve environmental pollution has more social and economic benefits. The main objective of this research was to assess the influence of styrene-butadiene-styrene (SBS) on the properties of low-density polyethylene (LDPE)/ethylene-vinyl acetate (EVA) modified asphalt, which aims to explore a feasible way to broaden the application of plastic in pavement engineering. Dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests were employed to evaluate the rheological behaviors of asphalt, and the temperature sensitivity explored by rotation viscosity. Furthermore, fluorescence microscopy (FM) and Flourier transform infrared (FTIR) spectroscopy tests were employed for microcosmic analysis. Test results indicated that SBS could increase rutting factor and reduce temperature sensitivity of LDPE/EVA compound modified asphalt. What's more, BBR test results suggested that SBS has positive effect on the low-temperature cracking resistance. Additionally, based on FM and FTIR tests, the cross-linking between polymer with asphalt further strengthened which may be due to some chemical reactions occurring. In the above consideration, SBS has positive effect on the properties of asphalt, especially the thermal cracking resistance. It is a feasible way to broaden the application of plastic in pavement engineering and beneficial for environmental protection that modification asphalt by SBS, LDPE and EVA.

Towards the low-energy usage of high viscosity asphalt in porous asphalt pavements: A case study of warm-mix asphalt additives

The problems of energy waste and pollutant gas emissions caused by the high-temperature construction of high viscosity asphalt (HVA) for porous pavements may be effectively solved by the warm-mix asphalt (WMA) additives. In this paper, the rheological properties of HVA with WMA additives were investigated considering the application in porous pavement. First, the influences of different dosages of Sasobit, EC120, Evotherm, foaming water on the conventional properties of HVA were investigated by rotational viscosity, absolute viscosity (60 °C), toughness and tenacity, penetration, softening point, and ductility (5 °C). The four optimum dosages of Sasobit (3%), EC120 (3%), Evotherm (1%), and foaming water (4%) were determined. Second, the rheological properties at the high-temperature, intermediate-temperature, and low-temperature of HVA with the four optimum dosages of WMA additives were studied by dynamic shear rheometer (DSR) test and bending beam rheometer (BBR) test. The result showed that the rotational viscosity (135 °C) of HVA was significantly reduced by the WMA additives, thereby improving the workability of the HVA. Meanwhile, the WMA additives at optimum dosage can improve the high-temperature rheological properties of HVA except for foaming water. However, Sasobit, EC120, and foaming water have adverse effects on the intermediate-temperature fatigue performance and low-temperature crack resistance of HVA. By comprehensive comparison, it is suggested that HVA with 1% Evotherm is more suitable for the construction in porous asphalt pavements.

Preparation and experimental research on the properties of neodymium iron boron magnetic powder modified asphalt

Waterproof adhesive layer is an important part of the asphalt pavement system for steel bridge decks. To improve the strength and durability of the paving structure, it is necessary to focus on the high-temperature performance and bonding properties of the waterproof adhesive layer. In this paper, Neodymium iron boron magnetic powder (NP) mixed with SBS modified asphalt was used to prepare NP-SBS composite modified asphalt (NSA) for the waterproof adhesive layer material of the steel bridge deck pavement structure. The excellent mechanical and magnetic properties of NP are used to enhance the related properties of the waterproof adhesive layer. The dynamic shear rheometer (DSR) test, the bending beam rheometer (BBR) test, the direct-tensile-loading test, and the direct-shear-loading test with 6 NP contents (0%, 2%, 4%, 6%, 8%, 10%) were conducted to evaluate the high-temperature performance, the low-temperature performance, the tensile strength and the shear strength of the unmagnetized and magnetized NSA. Through these tests, the variation of rheological properties and bonding properties of NSA could be analyzed. The research results showed that the addition of NP improved the high-temperature performance of NSA, but the effect of the powder mortar had an adverse effect on the low-temperature performance. The tensile strength and shear strength of the NSA increased with the increase of the amount of NP, and the amount of 1.0 L/m2 and the NP content of 6% can achieve better bonding properties. After magnetization, the high-temperature performance and bonding properties of NSA will be further improved, but the low-temperature performance will also be further decreased. It reflects the effect of NP on powder modification, magnetic bonding, and magnetic hardening of NSA. The research results show that NSA has excellent high-temperature performance and bonding properties, which can provide a reference for the subsequent research and application of NSA.

Influence of zinc oxide/expanded vermiculite composite on the rheological and anti-aging properties of bitumen

The bitumen modifier, zinc oxide (ZnO)/expanded vermiculite (EVMT) composite (ZnO/EVMT), was introduced into the bitumen with a dosage of 4%, 5%, and 6%. The surface morphology of EVMT and ZnO/EVMT was characterized by a field emission scanning microscope (FESEM). Further, the Superpave continuous grade of bitumen containing different amounts of ZnO/EVMT was determined by the dynamic shear rheometer (DSR) test and bending beam rheometer (BBR) test. The bitumen samples were aged by thin film oven test (TFOT), pressure aging vessel (PAV) aging test and ultraviolet (UV) aging test, and the influence of different amounts of ZnO/EVMT on both physical and rheological properties of the bitumen before and after aging were investigated. Moreover, the influence of ZnO/EVMT on the molecular distribution during aging was investigated by analyzing the change in the proportion of large molecular size (LMS) obtained from gel permeation chromatography (GPC). The FESEM result shows the ZnO particles are uniformly supported on the EVMT surface. Moreover, ZnO/EVMT slightly influences the high-temperature performance and improves the low-temperature cracking resistance of bitumen. In addition, no matter what aging method is adopted, ZnO/EVMT effectively increases the retained penetration and phase angle aging index, and decreases the viscosity aging index and complex modulus aging index of the bitumen, demonstrating the effectiveness of ZnO/EVMT in both resisting the thermo- and photo-oxidative aging of bitumen. Meanwhile, 6% and 4% ZnO/EVMT exhibit the best inhibitory effect on thermo- and photo-oxidative aging of bitumen, respectively. According to the GPC results, the composite inhibits the transformation of small molecules to large molecules during aging, resulting in a lower LMS increment and better anti-aging properties of the modified bitumen.