SBS Modifier Research Articles

Anti-ageing properties of styrene–butadiene–styrene copolymer-modified asphalt combined with multi-walled carbon nanotubes

This paper presents the findings from a study conducted to evaluate the potential impact of Carbon Nanotubes (CNTs) on the anti-ageing properties of styrene–butadiene–styrene copolymer-modified asphalt (SBS PMA). Ageing Indexes (AIs) of conventional parameters, rheological parameters, and structural changes were employed to capture the changes in asphalt samples before and after ageing. For conventional parameters, AIs of viscosity at 60°C, penetration, and ductility were significantly decreased by the addition of CNTs. Rheological parameters were performed by Master curves and Han curves, including complex modulus (G*), elastic modulus (G′), viscous modulus (G″), and phase angle (δ). When the amount of CNTs below 0.5 wt.%, the AIs of G* in the low-frequency zone of mater curves for SBS PMA was smaller than the one without CNTs. On the other hand, when the amount of CNTs surpass 0.5 wt.%, the AIs of G* in high-frequency zone of mater curves for SBS PMA was large. CNTs provided unaged SBS PMA with lower slopes of log (G′) versus log (G″) plots and higher elastic modulus in the terminal region of the plot attributable to the deformation and relaxation of SBS and CNT particles. For structural changes, AI of carbonyl functions and butadiene functions for SBS PMA were larger than that of samples with CNTs; thus, SBS degradation was decreased by adding CNTs. Furthermore, the oxygen-uptake amount of blends combined with SBS and CNTs was lower than that of neat SBS modifiers, demonstrating its important effect on the anti-ageing properties of SBS-modified asphalt.

EVALUATION OF NORMAL AND MODIFIED ASPHALT ACCORDING TO CONVENTIONAL AND MODERN GRADING SYSTEMS

Asphalt plays a significant role in pavement quality. The need for high-performance pavements with long service life and low maintenance requirements is the motive behind thorough research and studies of asphalt characteristics. This research focuses on studying all sources of Egyptian asphalt over a span of time using both conventional and Superpave grading techniques in order to characterize asphalt performance and also to answer the question whether the Egyptian asphalts need modification. The results of this research indicate that all Egyptian normal (virgin) 60/70 asphalt samples from different sources failed to meet penetration grading requirements, viscosity grading standards AC-20 (high quality); with minor exceptions, viscosity grading system AC-20 (low quality), and both AR-8000 and AR-1000 Aged Residue grading systems. When Superpave grading system was employed, results indicate that all normal asphalt samples failed to meet the basic requirements (without traffic adjustment) according to the Egyptian climatic requirements for high reliability projects (PG70-10 and PG76-10). The testing results accommodate Superpave requirements for lower levels of reliability and/or lower level of conservativeness. This emphasizes the flexibility and reliability of Superpave grading system as compared to conventional grading systems. On the other hand all modified asphalt samples, using an SBS modifier, passed according to the base high reliability projects and/or high level of conservativeness requirements of the Superpave grading system. Finally it is concluded that Egyptian asphalt should be modified in order to provide satisfactory performance especially for high reliability projects in hot regions with high and/or slow traffic.

Low temperature properties of UV aged asphalts containing layered double hydroxides modifier.

In recent years, ultraviolet (UV) ageing of asphalt has attracted worldwide attention from researchers in the asphalt field. The UV radiation can result in the ageing of asphalt and thus influence its performance. So far, a variety of UV blocking materials have been investigated. In this paper, layered double hydroxides (LDHs) were introduced as the UV blocking materials into three different asphalts (S70, S90 and SBS modified asphalt). The low temperature properties, such as equivalent breaking point (EBP) and fatigue factor were tested and applied to estimate the UV blocking effects of LDHs on asphalts. The experimental results demonstrated that LDHs could effectively reduce the ageing index of S70 and S90, and lower the degradation rate of SBS modifier.

Effect of styrene–butadiene–styrene copolymer modification on properties of Saudi bitumen

ABSTRACTThis research investigates the effects of styrene-butadiene-styrene (SBS) copolymer and other plastomers on the behavior of Saudi bitumen. Three bitumen samples, extracted from three Saudi oil refineries, namely Ras Tanura, Riyadh, and Yanbu, were used in this study. The bitumen samples were mixed with different modifiers in various compositions, forming polymer modified bitumens (PMBs). Elasticity parameters, such as ductility and elastic recovery were measured and evaluated. Characteristics of raw bitumen were analyzed to observe the compatibility of bitumen with SBS and plastomers. Bitumen samples were suitable for SBS modification and SBS PMBs showed superior elasticity behaviors compared to plastomer blends.

Preparation and properties of high viscosity modified asphalt

High viscosity modified (HVM) asphalt was prepared by the addition of styrene–butadiene–styrene (SBS), plasticizer, crosslinker. The effect and proportion of each modifier in the preparation of HVM asphalt were studied. SBS was the major modifier and determined the basic properties of HVM asphalt. Plasticizer (furfural exact oil) and crosslinker (sulfur) as additional modifiers were necessary in improving the workability, stability, and aging resistance of modifier. The effect of aging and additional modifiers on the structure and rheological behavior of SBS modified (SM) asphalt was displayed by adopting various rheological tests. Plasticizer declined the rutting resistance of SM asphalt and increased the viscous behavior of SM asphalt after aging. The use of crosslinker led to the formation of polymer network and improved the aging resistance of SM asphalt. The morphology observation shows crosslinker led to the formation of polymer network and improved the compatibility between SBS and asphalt. Plasticizer prompted the swelling and dispersion of SBS in asphalt and improved the effect of crosslinker further. Aging destroyed the polymer phase seriously and there was still residual polymer phase in asphalt. POLYM. COMPOS., 38:936–946, 2017. © 2015 Society of Plastics Engineers

The temperature effects in aging index of asphalt during UV aging process

With increasing global warming and the corresponding increase in the emissions of Ultra Violet radiations, the effect of UV radiations on the aging of asphalt gained more attention from researchers. However, the Ultra Violet (UV) aging methods used by different researchers are quite different. And even the UV aging working temperatures were not the same. Most researchers simulated the UV aging at temperature ranging from 30°C to 80°C. So temperature (from 30°C to 80°C) effects in UV aging were investigated to find out whether the temperature effects can be ignored. Three temperatures (30°C, 50°C and 70°C) were carried out during UV aging procedure with other UV aging conditions kept the same. The softening point and penetration results indicate that temperature could only slightly influence the UV aging under 50°C condition. The aging index of asphalt and deterioration of SBS modified asphalt increase dramatically at UV aging temperature condition of 70°C. The temperature sweep tests performed by Dynamic Shear Rheometer (DSR) show the same tendency as softening point and penetration results. Fourier Transform infrared spectroscopy (FTIR) and mass change tests were carried out as well in this research. Oxidation degree of asphalt and deterioration degree of SBS modifier both increase at 70°C UV aging temperature according to FTIR results. The mass changes results show that mass reducing ratios under UV condition are almost four times higher than heating condition for base asphalt and thirteen times for SBS modified asphalt. So the temperature effects on UV aging cannot be ignored and the suggesting UV aging temperature is under 50°C.

Aging mechanism of SBS modified asphalt based on chemical reaction kinetics

Research on aging mechanism of SBS modified asphalt can provide theoretical and technical support not only for the choice of asphalt pavement materials but also for recycling of SBS modified asphalt pavement. Dynamic equations of asphalt under different aging conditions were respectively established according to chemical reaction kinetics. And two kinds of micro analysis methods, component analysis and GPC (gel permeation chromatography), were used to analyze the change of asphalt composition and asphalt molecular structure during the aging process. In addition, the correlation between activation energy and asphalt microscopic components, asphalt molecular structure was analyzed through grey entropy theory analysis method. Different from previous research, the results demonstrate that the activation energy of asphalt is not a constant index. SBS network structure loses gradually due to the degradation of SBS modifier during the aging process. SBS modified asphalt after short-term aging degrades to more medium molecular size structure, which makes the activation energy become lower and improves asphalt temperature sensitivity. However, the SBS modifier after long-term aging has almost degraded completely, which increases the activation energy and makes asphalt temperature sensitivity approximate to base asphalt. The results of grey entropy theory analysis show that the activation energy will be reduced with the decrease of saturate content, the increase of medium molecular size structure content and resins content.

Mitigation of moisture damage in asphalt concrete: Testing techniques and additives/modifiers effectiveness

Moisture damage is a serious pavement distress that most transportation agencies face. It’s complicated mechanisms are dependent on several factors in asphalt pavement. This phenomenon triggers several pavement distresses, thus costing the country billions of dollars in pavement maintenance and rehabilitation. The most traditional technique adopted to mitigate moisture damage is adding selected additives or modifiers to asphalt mixtures. The additives and modifiers are used during construction to improve water resistance in asphalt pavement. However, each additive or modifier performs differently. This study evaluates the effects of two additives and two modifiers on the moisture susceptibility of two asphalt mixes. The additives include a liquid anti-stripping agent and hydrated lime while the modifiers include styrene butadiene styrene (SBS) and polyphosphoric acid (PPA). The effectiveness of the additives and modifiers was evaluated by conducting three mixture tests, including the Lottman AASHTO T283-02 test with five freezing and thawing (FT) cycles, the wheel-tracking test, and a fracture test using semicircular bending (SCB) specimens. The Lottman AASHTO T283-02 showed that adding liquid anti-strip to asphalt binder produced the best moisture resistance for both mixes followed by hydrated lime. The wheel track test showed that hydrated lime and SBS modifiers resulted in the least rut depth when used in both mixes. The results of the fracture test showed that liquid anti-strip and hydrated lime produced the highest fracture resistance. On the other hand, the three above test results indicated that PPA may not control asphalt mixers’ moisture susceptibility.

The research for thermal behaviour, creep properties and morphology of SBS-modified asphalt

Crosslinker and plasticizer were used to prepare Styrene-butadiene-styrene (SBS) compound-modified asphalt. The physical and rheological properties of modified asphalt were tested, and the morphology observation and thermal analysis were used to study the structural characteristics of modified asphalt further. The physical tests showed that plasticizer (dioctyl phthalate) improved the low-temperature properties of SBS-modified (SM) asphalt and crosslinker (sulphur) improved the stability and elastic recovery of SBS/plasticizer-modified (SPM) asphalt. The SBS/plasticizer/crosslinker-modified (SPCM) asphalt owns better physical properties before and after ageing. The rheological properties were studied by using creep tests. Creep tests indicated that plasticizer declined the deformation resistance of SM asphalt and crosslinker increased the recoverable deformation of SPM asphalt. Morphology observation showed that crosslinker improved the compatibility between SBS and asphalt greatly and ageing prompted the degradation of SBS to a great extent. Thermal analysis showed the effect of plasticizer and crosslinker on the thermal behaviour of SM asphalt, and the calculation for E a and endothermic peak area showed the structural characteristics of modified asphalt before and after ageing.

Effects of Using Sasobit and SBS on the Engineering Properties of Bitumen and Stone Mastic Asphalt

AbstractUsing hard and polymer-modified binders in stone mastic asphalt mixtures reduces workability considerably. In this study, Sasobit (Sasolwax, Worthdamm, Hamburg) is used in bitumen to increase the workability and efficiency of styrene-butadiene-styrene (SBS)–modified binders. The properties of SBS-modified and Sasobit-modified binders and mixtures were evaluated for their rheological and mechanical performances using different experimental techniques such as rheological bitumen tests—i.e., dynamic shear rheometer (DSR), bending beam rheometer (BBR), and hot-mixture performance tests; i.e., dynamic creep, fatigue, and toughness index tests. Sasobit improves the effectiveness of SBS modification, especially at medium to high temperatures, although it is not as flexible as SBS at low temperatures. In some cases, SBS modification is more effective than Sasobit modification when used alone. However, a better performance is achieved when 3% SBS plus 3% Sasobit is used when the two modifiers are mixed in ...

Mechanism of fume suppression and performance on asphalt of expanded graphite for pavement under high temperature condition

Fume suppression mechanisms and the effect of expanded graphite on the performance of asphalt were studied by applying infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and comprehensive thermal analysis (TG, DSC). The experimental results confirm that asphalt which is mixed with expandable graphite will expand in the process of hot mix, and the expanded graphite layer will swell by the light component in the asphalt. The light component in the asphalt and PAHs adsorption on expanded graphite surface or part of the plug in the expanded graphite layer between plates made nucleation crystallization growth. And the Van der Waals force and the bonding of the lattice can effectively restrain the asphalt fume release. Meanwhile, the expanding agent with oxidative can spread into the asphalt, leading to asphalt oxygenated and plastic abate, while the ductility decreases. Expanded graphite, SBS modifier and environment-friendly plasticizers are used to composite modified asphalt. According to asphalt fume release experiment, normal test of asphalt performance, Brookfield viscosity test, RTFOT test and asphalt mixture tests (high temperature stability, low temperature stability, water stability), it has been proven that the modified asphalt’s performance is better than that of matrix asphalt and equivalent to that of SBS modified asphalt. Furthermore, it has good fume suppression effect.

Software development on SBS modified asphalt image processing and analysis

SBS modified asphalt is made of the base asphalt, adding a certain proportion of SBS modifier. To make SBS uniformly dispersed in asphalt, we can use some methods such as mixing. Meanwhile, in order to form SBS blends, we should add a certain proportion of exclusive stabilizer. We can take advantage of the good physical properties of SBS to modify base asphalt. Obtaining the numerical characteristics through the processing and analysis of the microscopic image has great significance forSBS modified asphalt production, performance test and improvement. This paper introduces SBS modified asphalt special image processing and analysis system based on MATLAB GUIDE. We used the GUIODE to design a friendly graphical user interface(GUI). The func- tions of processing include image cropping, image gray-level transform, DFT/DCT,image binarization, threshold segmentation, morphological operation and so on. The function of image analysis is implemented by morpholog- ical feature extraction.

Microstructure and Temperature Characterization of Compound Crumb Rubber Modified Asphalt

Compound Crumb Rubber Modified Asphalt (CCRMA) is a mixture of waste rubber tire powder, SBS modifier and asphalt in order to modify the characteristics of asphalt. The application of using crumb rubber powder in making CCRMA is important in improvement of working characteristics of asphalt as well as in pollution control and environment protection. CCRMA, crumb rubber particles, SBS modifier and base asphalt have been examined by Scanning Electron Microscope (SEM) to observe the microcosmic appearance and the characteristic distribution of crumb rubber particles and SBS modifier in asphalt. The rotary viscometer test and dynamic shear test of CCRMA were carried out by rotational viscometer and Dynamic Shear Rheology (DSR). The influences of rubber powder content and reaction time to viscosity of CCRMA have been studied. In the stage of current study, complex modulus and phase angle of CCRMA are parameters reflecting viscoelasticity, the relation between them and temperature are researched.

Experimental Research on Compatibility between SBS Modifier and Base Asphalt

Firstly we analyzed the effect of the type of matrix asphalt, the dosage of SBS modifier and shear time on the properties of SBS modified asphalt with the analysis method of Multi-factor, then we analyzed the mechanism of interaction between SBS modifier and matrix asphalt based on the four-component test analysis. The results showed that different types of matrix asphalt had different modification effect. Among them, the matrix asphalt A and SBS modifier had the best compatibility. The high content of asphaltene helped to improve the temperature properties of asphalt, the asphalt with high content of aromatic was much easier to be modified. As the dosage of SBS modifier reached 4.2%, the interconnected network had been formed, the modification effect achieved the optimal result, but the modification effect would be reduced with an additional contribution of SBS modifier. With the prolonged shear time, SBS modifier could be dispersed in the matrix asphalt more uniformly, however, the shear time should not be too long, the optimum shear time is 40min.

The Research of Shear Property of SBS Modified Asphalt and Aggregated Rock

In view of the limitation that happens when the adhesion between SBS modified asphalt and aggregated rock is evaluated by water-boiling method, on the basis of adhesion mechanism analysis of asphalt and aggregated rock, we design the evaluation method of the adhesion between asphalt and aggregated rock based on shear test, advance the quantitative index to evaluate the adhesion——shear strength, and validate the feasibility of shear strength index, analyze how the type and dosage of SBS modifier and the temperature of test influence the adhesive effect of SBS modified asphalt and aggregated rock. Result shows that The incorporation of SBS significantly improve the adhesion of asphalt and stone , especially the effect of star-modified asphalt and with the increase of dosage of SBS ,the adhension of asphalt and stone significantly increased, the shear strength of SBS modified asphalt and stone is increased about 100% than matrix asphalt when the dosage is 4%. It also describes that the shear strength index can quantitatively evaluate the effect of asphalt binder and aggregates to provide a reference for performance evaluation and quality control of modified asphalt .

Aging mechanism and effective recycling ratio of SBS modified asphalt

With the increase of road service life, SBS (styrene–butadiene–styrene block copolymers) modified asphalt waste materials are being discarded. Taking advantage of these waste pavement surfacing materials will not only reduce the pollution of the environment, but also save resources. This paper analyzes the aging mechanism of SBS modified asphalt through macroscopic examination and microcosmic analysis using conventional performance indicators: SHRP performance index, component analysis, Gel Permeation Chromatography (GPC), Infrared Spectrum Analysis (IR), etc. The recycling effectiveness was evaluated through the indicator of effective recycling ratio which is put forward by laboratory test. The results illustrated that the aging of SBS modified asphalt was formed by both aging of matrix asphalt and aging of SBS modifier. SBS modifier degradation could slow down the aging reaction of matrix asphalt because SBS modifier would degrade to small molecules in the process of aging. In addition, the matrix asphalt could also play a role in the protection of the SBS modifier. Therefore, the mutual protection of both makes the anti-aging performance of the modified asphalt significantly better than that of matrix asphalt. We also evaluated the recycling effectiveness of aged SBS modified asphalt under the presence or absence of rejuvenating agent, different mixing time and temperature. The presence of rejuvenating agent as well as appropriately increasing mixing temperature and time are proved to be able to improve the recycling effectiveness.

Performance evaluation of WMA plant and field trial mixes

Warm mix asphalt (WMA) technology is still in its infancy, with significant scope for further exploration of the benefits of incorporation of higher percentages of recycled asphalt RA as well as modified binders for performance enhancement. The objective of this study was to evaluate three different WMA technologies, namely chemical and organic additives as well as foamed technology, within different mix compositions. The variables in mix composition included 10–20 % RA in surfacing mixes and 20–40 % RA in base layer mixes. The binder variables included two base binders, control mixes (no modifier) and ethylene vinyl acetate (EVA) or styrene butadiene styrene (SBS) with or without WMA technologies. A partial factorial experimental design based on the above variables was developed. Full-scale plant mixes and field (construction) mixes were produced and beams were prepared from compacted slabs and tested under 4 point loading to provide master curves and fatigue relations. Comparative results show inconsistent trends between different technologies. control mixes (HMA) can provide both higher and lower flexural stiffness than their WMA counterparts. EVA or SBS modification can provide either superior or inferior mixes to their WMA counterparts depending on the WMA technology. Generally the fatigue results of both the HMA surfacing and base layer mixes at both RA contents are superior to their equivalent WMA counterparts. The implications of these differences are explored in the publication.

Evaluation of the conventional and rheological properties of SBS + Sasobit modified binder

The effort of constructing durable roads with higher standards has required to research the usage of various additives in bituminous coating so far. Nowadays polymer modification is effectively applied, and additives, which can provide better compaction and less expense by improving workability features are considered. These additives contribute to performance as well as workability. In this study conventional and rheological properties of binders, which include styrene–butadiene–styrene (SBS) in various rates and an organic warm mixture additive (Sasobit®), are investigated. The effects of additives, which are used separately and together in the binder are examined. As a result, it was found out that warm-mix-additive modification has better performance than SBS modification in terms of temperature susceptibility and SBS modification has better than Sasobit modification in terms of rutting parameter especially in high temperatures. Also, Sasobit® modification significantly decreased the viscosity and increased the softening point compared to SBS modification. The results show that the properties of the bitumen modified with combined additives are significantly different from that of individually modified bitumen. If additives are used in the same mixture together, warm-mix-additive can be added in certain ratios into SBS modification in order to obtain same properties stated above.

Analysis on the Impact of the Type and Content of SBS on the Performance of the Modified Asphalt Mixture

The types and contents of styrene-butadiene-styrene (SBS) modifier are two important factors of SBS modified asphalt mixtures. Nowadays, SBS are extensively utilized to modified asphalt in order to improve the performance of the flexible pavement. The objective of this study is to determine a best selection of types and contents of SBS modifier, which can improve high-temperature stability; low-temperature anti-cracking performance and moisture susceptibility of SBS modified asphalt mixture. The mixtures with four types of SBS (Linear A, Linear B, Star A, Star B) and the different contents of each type SBS including Linear SBS of 0%, 3%, 4%, 4.5% and Star SBS of 0%, 3%, 3.5%, 4%, were evaluated for the pavement performance of them under laboratory conditions. Wheel tracking test, beam bending test and freeze-thaw tensile strength test were chosen and carried out to determine high-temperature stability, low-temperature anti-cracking performance and the moisture susceptibility respectively. The laboratory testing results indicate that Star SBS show the more effective effects than Linear SBS to improve the high-temperature stability, low-temperature anti-cracking performance and moisture susceptibility of SBS modified asphalt mixture, and the optimum content of SBS can also play a key role the improvement of the pavement performance.

The Regeneration of Aged SBS Modified Asphalt via Re-reticulating SBS Particles Under Gamma Irradiation

The damaged reticulation structure of SBS modifier was considered to be a main reason for the deterioration of pavement performances. The authors regenerated the damaged reticulation structure of aged SBS modified asphalt (SBS MA) by a gamma irradiation technology and assessed its potential applications. Changes of morphologies and chemical components in regenerated SBS MA were investigated by polarizing microscopy and Fourier transform infrared spectroscopy, respectively. Physical properties of regenerated SBS MA were measured to assess its potential applications. Results showed that reticulations were largely restored after 40 kGy irradiation and met the demand of pavement performances.