Dynamic Shear Rheometer Test Research Articles

Low-temperature rheological properties and micro-mechanism of DIBCH plasticizer modified bitumen

ABSTRACT In this study, a diisobutyl cyclohexane dicarboxylate (DIBCH) plasticizer was used to modify bitumen for preventing cracking and improving the performance of bitumen pavements. The low-temperature rheological properties of the DIBCH plasticizer–incorporated bitumen were studied via bending beam rheometer (BBR) and dynamic shear rheometer (DSR) tests. Fourier transform infrared spectroscopy (FTIR) and saturate, aromatic, resin, and asphaltene (SARA) fraction tests were performed to investigate the mechanism of the modification of bitumen by the DIBCH plasticizer. The results indicated that the incorporation of DIBCH could enhance the low-temperature deformation ability and stress-relaxation ability of bitumen, and the higher the DIBCH content, the greater the improvement in the low-temperature performance of the bitumen. Furthermore, a microscopic analysis revealed that the modification mechanism of bitumen by the DIBCH plasticizer was that of physical blending, and they did not react chemically. Moreover, the incorporation of DIBCH increased the proportion of light components in the bitumen, thereby improving its low-temperature properties.

Evaluation and optimization of asphalt binder and mixture modified with high activated crumb rubber content

High-content rubberized asphalt (HCRA) is a road engineering material with favorable economic and environmental benefits. However, HCRA is still not widely used due to concerns of workability and storage stability. To improve rubber content and maintain rubberized asphalt (RA) performance, five RAs with different activated powder contents were prepared by wet process. Firstly, composite viscosity and softening point difference were used to optimize the preparation process of activated powder and RA. The dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests were carried out and the stability index was proposed to evaluate performance of HCRA. Finally, the mixture performances of HCRA, base asphalt and SBS modified asphalt were compared. The results show that the 60-mesh rubber powder with 20% waste oil is beneficial to reduce viscosity and improve compatibility of HCRA when treated by microwave for 2 mins and sheared for 5 h. As the powder content increases, RAs have excellent high and low temperature performances. Overall, the performance of HCRA binder and mixture with 60% content of rubber powder possess optimal comprehensive properties in terms of high temperature rutting resistance, cracking resistance, and moisture resistance. This study helps facilitate the incorporation of high content rubber in RA and promote its potential application in road engineering.

Effects of Alkylamines-Based and Polyalkylene Glycol-Based Bonding Enhancers on the Performance of Asphalt Binders

The premature deterioration of asphalt pavements usually occurs due to different moisture damage mechanisms resulting in stripping, ravelling, potholes, and disintegration without proper treatment. Numerous efforts have been taken into consideration to improve the bonding between materials, hence prolonging the pavement life. This study evaluates the performance of asphalt binders incorporating Alkylamines-based (ALM) and Polyalkylene Glycol-based (PLG) bonding enhancers. Each bonding enhancer at 0.5% and 1.0% based on the weight of asphalt binder was separately blended with the conventional asphalt binder 60/70 penetration grade using a high shear mixer at 1000 rpm for 30 minutes at 160°C. The physical and rheological properties of modified binders were evaluated through penetration value, softening point, ductility, elastic recovery, rotational viscosity (RV), and dynamic shear rheometer (DSR) tests. Overall, additions of ALM and PLG show identical penetration grade compared to the control sample. Both ALM and PLG showcase a higher ductility and elastic recovery than the neat binder. The DSR test indicates the incorporation of bonding enhancers improves the modified binders’ rutting performance. While the application of ALM at 0.5% dosage increased the binder failure temperature out of all the tested samples, where the failure temperature is at 70°C, compared to others at 64°C. Studies at mastics and mixture levels should be conducted to appropriately understand the effect of bonding enhancer on the bituminous materials.

Study on preparation and properties of new thermosetting epoxy asphalt

Epoxy asphalt is not widely used because of its high price and miscibility problems of the epoxy resin and asphalt. Herein, a new thermosetting epoxy asphalt (NEA) was prepared with oleylamine as a curing agent. The tensile test showed that NEA has high tensile strength (4.4 MPa) and fracture strain (594%). Fourier transform infrared analysis of the NEA showed that the unsaturated double bond in oleylamine reacted with the active group in asphalt, which effectively introduced asphalt into the network structure formed by curing epoxy resin. The non-polar long chain on oleylamine awarded the NEA with excellent toughness and effective miscibility with non-polar asphalt, which can be confirmed by tensile test and fluorescence microanalysis. The temperature scanning results and the master curve obtained by dynamic shear rheometer test revealed that NEA is an excellent damping material with excellent low-frequency and high-frequency performance. The reaction mechanism of NEA was proposed based on the macro and micro analysis results. This study provided a facile approach for preparing a low-cost NEA modified asphalt by oleylamine curing agent having good miscibility with asphalt and enhanced mechanical properties, and hence can be counted as an alternative contender for applications in pavement, construction, and engineering industries.

Synergies on rheology and structural build-up of fresh cement pastes with nanoclays, nanosilica and viscosity modifying admixtures

Nanoclays, nanosilica and viscosity modifying admixtures can be used to tune rheological properties of cement pastes, in order to fulfill the requirements for non-conventional cast-in-place techniques. An experimental study on cement paste rheology was carried out to evaluate their combined effects on fluid cement pastes’ properties. A reference paste with cement blended with limestone filler and a low water to binder ratio was designed. A high range water reducing admixture (HRWRA), three types of viscosity modifying admixtures (VMA), and five nanocomponents (nanosilica and four different nanoclays) were added. Flowability, initial rheological properties and structural build-up of cement pastes were assessed with mini-cone slump test and dynamic shear rheometer test (DSR). The synergies between nanoclays, nanosilica and VMAs were evaluated. It was observed that an adequate combination of admixtures and nanoclays reduced the amount of HRWRA required to achieve target flowability, regarding the same components uncombined. The type and amount of VMAs and nanocomponents also produced changes on yield stress, viscosity and structural build-up. Their effect on structural build-up of fresh paste was related to reversible and non-reversible mechanisms, comparing the reduction of spread diameter of fresh samples stirred and left at rest over time measured with the mini-cone.

Evaluating the Rheological, Chemical and Morphological Properties of SBS Modified Asphalt-Binder under Multiple Aging and Rejuvenation Cycles

To investigate the influence of multiple cycles of aging and rejuvenation on the rheological, chemical, and morphological properties of styrene–butadiene–styrene (SBS)-modified asphalt-binders, the asphalt-binders were aged using two laboratory simulation methods, namely a rolling thin film oven (RTFO) test for short-term aging and pressure aging vessel (PAV) for long-term aging. The asphalt-binders were then rejuvenated with three types of rejuvenators (Type I, II, and III) with different dosages (i.e., 6%, 10%, and 14% for the first, second, and third rejuvenation, respectively). A dynamic shear rheometer (DSR) was then used to analyze the effect of rejuvenators on the rheological properties of all the asphalt-binders. The changes in the functional groups and microscopic morphology in the process of multiple aging and rejuvenation cycles were studied using Fourier transform infrared (FTIR) and atomic force microscopy (AFM). The results indicated that the three rejuvenators could soften the stiffness and restore the microstructures of the aged asphalt-binders in the process of repeated aging and rejuvenation from DSR and AFM testing. Considering the rutting and fatigue properties, the Type I rejuvenator exhibited the potential to achieve the desired rejuvenation effects under multiple rejuvenation cycles. During the multiple aging and rejuvenation cycles, the aging resistance of SBSMA decreased gradually from the FTIR results. This inherently limited the number of repeated rejuvenation cycles. This research is conducive to promoting the application of repeated penetrating rejuvenation.

Evaluation of the Aging of Styrene-Butadiene-Styrene Modified Asphalt Binder with Different Polymer Additives.

A wide variety of polymer additives have been widely used in recent years. However, the effect of different polymer additives on the durability of asphalt binders has not been investigated thoroughly. To evaluate the aging property of styrene-butadiene-styrene (SBS) asphalt binder with different polymer additives, three polymer modifiers, namely high modulus modifier (HMM), anti-rutting agent (ARA), and high viscosity modifier (HVM), were added to it. First, the Thin Film Over Test (TFOT) and Pressure Aging Vessel (PAV) was performed on the asphalt binders. The rheological properties of the four asphalt binders before and after aging were then checked by the Dynamic Shear Rheometer Test (DSR). The chemical compositions of the asphalt binders were determined by the Fourier Transform Infrared Spectrometer (FTIR) test. Several aging indicators were adopted to reflect the aging degree of the asphalt binders. The results show that when polymer additives are added to the SBS asphalt binder, the complex modulus, storage modulus, loss modulus, and rutting factor substantially increase and the phase angle decreases. All the test parameters become higher after aging. The phase angle of the SBS asphalt binder is the highest at both unaged and aged states, while its other parameters values are the smallest. Moreover, the Carbonyl Aging Indicator (CAI) of SBS with polymer additives becomes lower under both TFOT and PAV conditions, indicating that polymer additives can improve the aging resistance of SBS asphalt, of which HVM modifies the aging resistance best. Complex Modulus Aging Indicator (CMAI) and Storage Modulus Aging Indicator (SMAI) have the best correlation coefficients with CAI, and the two aging indicators can be used to predict the aging degree of polymer modified asphalt binders.

Evaluation of Rheological Characteristics of Graphite Modified Bitumen

The level of performance of asphalt concrete has a close relationship with the properties of bitumen used. This research evaluates the rheological parameters of graphite modified bitumen. Index properties tests were conducted on bitumen and graphite to determine their suitability. Dynamic viscosity and dynamic shear rheometer were conducted on bituminous binder modified with four different proportion of graphite ranging from 2% to 10% by bitumen weight. Dynamic viscosity test was conducted on bitumen and graphite modified bitumen at temperature of 1350C and 1650C using Brookfield Viscometer. The rheological properties are centered on phase angle (δ) and complex shear modulus (G*) which were determined on bitumen and graphite modified bitumen at temperature ranging from 520C – 700C at 10 rad/s frequency using Dynamic Shear Rheometer in accordance with ASTM D7175-15. The storage modulus (G'), loss modulus (G") and rutting parameters were then evaluated from phase angle and complex shear modulus. The bitumen and graphite modified bitumen showed that graphite modified bitumen has the highest complex shear modulus and rutting parameter of 8984 (kPa) and 33387 (kPa) at 10% graphite content. The results of viscosity helped to determine the mixing and compaction temperatures. Dynamic shear rheometer test results determined the elastic and viscous behaviour at various temperature. The higher the complex shear modulus and rutting parameter the stiffer the binder will resist deformation and rutting.

Evaluation for Low Temperature Performance of SBS Modified Asphalt by Dynamic Shear Rheometer Method

Finding an alternative or supplementary test method to evaluating the low temperature performance of asphalt is an area of considerable interest. This paper tries to explore the possibility of using the dynamic shear rheometer (DSR) method for assessing the low temperature properties of styrenebutadienestyrene (SBS) modified asphalt. In the study, 60/80 and 80/100 pen grade asphalt binders, named binder A-70, binder B-70 and binder C-90, are used to produce the SBS modified asphalt samples. After that, the low temperature performance of the asphalt binders is characterized by using bending beam rheometer (BBR) test. The results indicate that the low temperature performance of the different binders is related to the source of the binder. The low temperature performance of asphalt could be improved with the addition of the SBS. The DSR test is used to develop the complex modulus master curves for binders. Based on the principle of time–temperature conversion, the glass transition temperature of asphalt is calculated by the Williams–Landel–Ferry (WLF) equation. The glass transition temperatures (Tg) of base asphalt and the SBS modified asphalt are determined by the viscoelastic parameters of the master curve and the WLF equation coefficients based on the time–temperature superposition principle. By establishing the relationship between the critical temperature and the Tg of the asphalt binder, the effectiveness of the method established in this paper is verified. The advantage of this method is the ability to use the DSR test for the rapid evaluation of the low temperature performance of asphalt, which is able to reduce testing materials and save testing time as well. The glass transition temperature of the SBS modified asphalt is closely associated with aging degree, asphalt source and the SBS content.

Thermochemical liquefaction of wheat straw and its effectiveness as an extender for asphalt binders: Characterization of liquefied products and potential opportunities

Numerous attempts have been carried out to develop potential substitutes for petroleum asphalt binders from various biomass resources. This research aims to investigate the effectiveness of partially replacing asphalt binders with thermochemical liquefied products (LPs) of wheat straw. The LPs were obtained by acid-catalyzed liquefaction in organic solvents, based on which nine kinds of bio-asphalt binders distinguished by the type and content of LPs were prepared by mechanical stirring. To evaluate the physicochemical properties of the LPs, the Fourier transform infrared (FTIR) spectroscopy test, gel permeation chromatography (GPC) test, thermogravimetric (TG) test and rotational viscosity (RV) test were conducted. The potential advantages of bio-asphalt binders were explored by the RV test, dynamic shear rheometer (DSR) test, scanning electronic microscopy (SEM) test and FTIR test. The results demonstrate that LPs consist of 79%–88% bio-oils with low molecular weight and a small amount of solid residues. Compared with asphalt binders, more polar groups (e.g. hydroxyl, carbonyl and alcohol, etc.) with low boiling points are found in LPs, resulting in a lower volatilization and degradation temperature. There is a high chance for the fusion of LPs and asphalt binders to be physical integration. Further, the non-Newtonian flow behavior of asphalt binders is deepened by LPs. Nevertheless, better low-temperature cracking resistance and high-temperature performance are found from different types of bio-asphalt binders. It should be noted that the relationship between performances of bio-asphalt binders and the content of LPs needs more attention in further researches.

Micro- and Meso-scale homogeneity of asphalt mixtures with RAP in thermal-non-equilibrium condition

Reclaimed asphalt pavement (RAP) is a promising material that can be partially substituted into the newly constructed pavement. An appropriate production procedure is of great significance to produce high-quality recycled asphalt mixtures. This study performed an investigation on the micro and mesoscale homogeneity of asphalt mixtures produced by different mixing conditions. To this end, 36 mixing combinations, including three preheated RAP temperatures, three mixing times, and two aggregate types, were considered in this study. The diffusion sample composed of new and aged bitumen was obtained non-destructively using the aggregate tracking method (ATM). In what follows, the Fourier Transform Infrared Spectroscopy (FTIR) and Dynamic Shear Rheometer (DSR) tests were conducted to quantify the diffusion sample from the mechanical and chemical aspects, respectively. Accordingly, the homogeneity of asphalt mixtures containing RAP was analysed at the micro and mesoscales. The results indicated that mixing temperature dominantly controlled the migration behavior of binders, further determining the diffusion behavior between new bitumen and aged bitumen. Notably, the estimation of homogeneity of asphalt mixtures was found to be indicator-dependent. Using different indicators could induce distinct evaluation results or even opposite results. In general, the increase of mixing time would improve the complex modulus of the diffusion sample. The worst homogeneity was observed when the mixing temperature was around 110℃. Due to the variation in adhering to the bitumen binder, the aggregate type also influenced the micro and mesoscale homogeneity of asphalt mixtures.

Study of the self‐healing properties of aged asphalt‐binder regenerated using residual soybean‐oil

AbstractTo improve the self‐healing properties and reduce the reaction energy barrier during the self‐healing process of aged asphalt‐binders, this study utilized residual oil extracted from soybean to regenerate the aged asphalt‐binder and enhance its rheological properties including the self‐recovery potential. The self‐healing properties from the reaction energy barrier and chemical structure were characterized using molecular dynamic simulations. In addition, the rheological properties were measured and quantified using the dynamic shear rheometer test device. From the study results, the least reaction energy (30.16 kcal·mol−1) barrier registered during the self‐healing process of the regenerated asphalt‐binder occurred at 5.8 wt% residual Soybean‐oil, and was thus, deemed as the optimum oil content. The results further indicated that the residual soybean‐oil had a significant influence on the spatial configuration of the molecules in the aged asphalt‐binder, particularly on the saturates and aromatics components. Overall, the study findings indicated that residual Soybean‐oil can potentially reduce the reaction energy barrier of aged asphalt‐binders and enhance the self‐healing properties including fatigue life.

Predicting the low-temperature performance of asphalt binder based on rheological model

At present, the test methods to evaluate the low-temperature performance of asphalt binder focus on bending beam rheometer (BBR), and dynamic shear rheometer (DSR) is mainly used for high-temperature and medium-temperature tests. The reason is that when the test is in the low-temperature range, the instrument compliance errors are an unavoidable problem in DSR test. To solve this, based on the frequency sweep test of DSR, the modified Havriliak-Negami (MHN) model was employed to deduce the temperature at which asphalt binder undergoing the glass transition, and the torsion cylinder (TC) test and differential scanning calorimeter (DSC) were conducted to verify its correctness. Furthermore, the relationship between this approach and the low-temperature performance of asphalt binder is established by nonlinear fitting and linear regression analysis. This study presented an approach to predict the low-temperature performance of asphalt binder based on rheological model, which provides a solution to the difficulty of evaluating the low-temperature performance of asphalt binder using DSR.

Predicting a Model for Modified Asphalt Cement Rutting Parameters

This paper aims to investigate the relationship between the Superpave rutting parameter of asphalt (G﹡/sin δ) by conducting Dynamic Shear Rheometer (DSR) tests with the rut depth values obtained by the wheel track device. The twenty asphalt mixtures have been prepared with twenty types of unmodified asphalts and Polymer-Modified Binders (PMBs). SBS was used to produce PMBs. The twenty base and modified asphalts have been used to prepare asphalt paving mixtures required to conduct wheel track tests. The predicted model of asphalt mixtures rut depth related to asphalt rutting parameter (G﹡/sin δ) values has been founded. Besides, the minimum limits of (G﹡/sin δ) of aged asphalt have been gotten as 3.25 kPa for Iraqi asphalt cement.

Study on Pitch Performance Deterioration in Chemical Mechanical Polishing of Fused Silica

Fused silica (FS) has been widely applied in astronomical telescopes, laser systems, and optical communication. The excellent fabrication of a fused silica surface requires high efficiency and high smoothness. Here, based on the ceria slurry and the pitch lap, the study of chemical mechanical polishing (CMP) of FS surface was carried out. The variations of the polishing removal rate (RR) and polished surface roughness Rq of FS with the polishing time were investigated. Meanwhile, the variations of the pitch performance during the CMP process were analyzed. Compared with the original pitch, the Rq of the used pitch presented an obvious decrement and the thickness of the used pitch was reduced. Scanning electronic microscopy was used to observe the morphologic change of the pitch. Attenuated total reflection-Fourier transform infrared spectroscopy was used to evaluate the chemical change of the pitch. The surface roughness Rq of the pitch was characterized. The viscoelastic characteristics of the pitch were investigated by dynamic shear rheometer tests. The relative mechanism of the pitch performance deterioration was discussed.

Micromechanical simulation of porous asphalt mixture compaction using discrete element method (DEM)

The paper aims to simulate the micromechanical behavior of asphalt mixtures during the compaction process using the Discrete Element Method (DEM). The interactions between the components of a Porous Asphalt (PA) mixture were represented using an Elastic Viscoelastic Contact Model (EVCM), which is a user-defined model implemented in EDEM software, developed based on linear elastic and Burger’s viscoelastic constitutive equations. The macroscale parameters of asphalt mortar were characterized using the nonlinear regression analysis of master curves obtained from Dynamic Shear Rheometer (DSR) tests. The verification process of EVCM successfully indicated that the computations trends fall within the range of expected values for the typical asphalt mixture material. Further, a Superpave Gyratory Compaction (SGC) test was carried out and the obtained sample was scanned using X-ray Computed Tomography (X-ray CT) to capture the air void distributions. The DEM was utilized where digital samples were established to simulate the overall process of laboratory and field compaction. The simulation results showed that the model provided a comparable prediction of responses and demonstrated the capability of SGC to fabricate a representative sample. The influence of temperature on the asphalt compaction process was explored and the results implied that temperature decreasing adversely affects the compactability and dramatically increases the demanded compaction efforts which are consistent with the law of viscoelasticity. On the contrary, when the temperature is high, the asphalt binder becomes too fluid and roller loads will simply displace, or “shove” the mat rather than compact it. Tracking the change in the air voids proportion indicates that the motion of aggregates is rather compound. The aggregates flowed vertically downwards in line with the compacting orientation while moved horizontally outwards away from the center. All in all, the findings confirm that the concept is technically practicable, affording the model great potential to help researchers understand the microstructural phases of asphalt mixture during the compaction.

Study on the modified fiber with nacre layer structure based on bionic coating and molybdenum disulfide co‐construction incorporated asphalt

AbstractA green and efficient two‐step method was used to modify the surface of aramid fiber with a double shell structure by compounding MoS2 with dopamine and tannic acid to develop nacre fiber with enhanced interfacial effect, which was in turn applied to prepare nacre fiber incorporated modified asphalt. The nacre fiber and its incorporated modified asphalt were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), fluorescence microscopy (FM), and dynamic shear rheometer (DSR). FTIR results indicated that the nacre fiber was highly dispersed in the matrix asphalt while it was highly thermally stable (THRI of 207.4°C) as confirmed by thermogravimetric analysis. FM and SEM analyses confirmed that the nacre fiber formed a uniformly dispersed and well‐developed three‐dimensional network structure in the matrix asphalt, which endorsed the nacre fiber modified asphalt with enhanced mechanical and viscoelastic properties as confirmed by DSR tests.

Micromechanics modeling of viscoelastic asphalt-filler composite system with and without fatigue cracks

Fatigue cracking of viscoelastic asphalt composite materials is one of the major distresses in asphalt pavements. To quantify the weakening effect of the fatigue cracks on the mechanical properties of the viscoelastic asphalt composite materials, this study takes an asphalt-filler composite system as an example, and micromechanics models are proposed by combining Eshbely’s equivalent inclusion theory and Mori-Tanaka approach. Dynamic shear rheometer (DSR) tests are performed on the viscoelastic asphalt-filler composite systems with two volumetric contents of inclusion (10% and 27%) at different frequencies (0.1–100 Hz), temperatures (15℃, 20℃, 25℃) and strain levels (0.01%-0.1% for nondestructive DSR tests; 5%, 6%, 7% for destructive DSR tests). Results show that the predicted shear modulus results by a modified viscoelastic strengthening coefficient (VSC) model match with the test results at both low and high filler contents. Then a viscoelastic strengthening coefficient with fatigue cracks (VSC-f) model is proved being capable of accurately predicting the shear modulus for the viscoelastic asphalt-filler composite systems at different strain levels, temperatures, filler contents and damage levels. Both the VSC and the VSC-f model are derived to be dependent of loading frequency, temperature and filler content, but independent of strain level.

Laboratory Properties of Waste PET Plastic-Modified Asphalt Mixes

Commercial polymers have been used in pavement modification for decades; however, a major drawback of these polymers is their high cost. Waste plastic polymers could be used as a sustainable and cost-effective additive for improving asphalt properties, attaining combined environmental–economic benefits. Since 2019, in Australia, trial segments of roads have been built using waste materials, including plastic, requiring that laboratory evaluations first be carried out. This study aims to examine and evaluate the effect of using a domestic waste plastic, polyethylene terephthalate (PET), in modifying C320 bitumen. The assessment of several contents of PET-modified bitumen is carried out in two phases: modified bitumen binders and modified asphalt mixtures. Dynamic shear rheometer (DSR) and rolling thin film oven tests (RTFOT) were utilised to investigate the engineering properties and visco-elastic behaviour of plastic-modified bitumen binders. For evaluating the engineering properties of the plastic-modified asphalt mixtures, the Marshall stability, Marshall flow, Marshall quotient and rutting tests were conducted. The results demonstrated that 6–8% is the ideal percentage of waste plastic proposed to amend and enhance the stiffness and elasticity behaviour of asphalt binders. Furthermore, the 8% waste PET-modified asphalt mixture showed the most improvement in stability and rutting resistance, as indicated by increased Marshal stability, increased Marshall quotient and decreased rut depth. Future fatigue and modulus stiffness tests on waste plastic-modified asphalt mixtures are suggested to further investigate the mechanical properties.

Evaluation of Properties and Micro-Characteristics of Waste Polyurethane/Styrene-Butadiene-Styrene Composite Modified Asphalt.

In order to solve the problems caused by asphalt diseases and prolong the life cycle of asphalt pavement, many studies on the properties of modified asphalt have been conducted, especially polyurethane (PU) modified asphalt. This study is to replace part of the styrene-butadiene-styrene (SBS) modifier with waste polyurethane (WP), for preparing WP/SBS composite modified asphalt, as well as exploring its properties and microstructure. On this basis, this paper studied the basic performance of WP/SBS composite modified asphalt with a conventional performance test, to analyze the high- and low-temperature rheological properties, permanent deformation resistance and storage stability of WP/SBS composite modified asphalt by dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. The microstructure of WP/SBS composite modified asphalt was also observed by fluorescence microscope (FM) and Fourier transform infrared spectroscopy (FTIR), as well as the reaction between WP and asphalt. According to the results of this study, WP can replace SBS as a modifier to prepare WP/SBS composite modified asphalt with good low-temperature resistance, whose high-temperature performance will be lower than that of SBS modified asphalt. After comprehensive consideration, 4% SBS content and 15% WPU content (4 S/15 W) are determined as the suitable types of WPU/SBS composite modified asphalt.