Bending Beam Rheometer Research Articles

Effects of different penetration‐grade asphalt binders on the microstructure, mechanical, and aging properties of cold‐mixed epoxy asphalt binder

AbstractThe aim of this research was to investigate asphalt effects on the storage stability, mechanical properties and micro‐properties of cold‐mixed epoxy asphalt binder (CEAB). Firstly, four CEAB were prepared with four base asphalt types and storage stability, miscibility analyses were performed by fluorescence microscopy (FM). Then, cured CEAB and epoxy resin (ER) were treated by ultraviolet aging. Tensile test, dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy were applied to clarify the mechanical properties and micro‐properties of aged and unaged CEAB. Also, bending beam rheometer (BBR) tests were conducted to study low‐temperature performance of CEAB. The results revealed that the CEAB prepared with asphalt with penetration grade 60 ~ 80 presented superior storage stability, miscibility, mechanical properties and that prepared with penetration graded 80 ~ 100 showed slightly better low‐temperature performance. Moreover, asphalt properties were found to have little impacts while epoxy resin played a key role in the mechanical properties of CEAB. Glass transition temperature () of the CEAB containing penetration‐graded asphalt 80 ~ 100 decreased more significantly than that with penetration‐graded asphalt 60 ~ 80, and it was also found that the CEAB prepared with base asphalt with higher molecular weight polydispersity index had better ductility performance.

Investigating the properties of a novel organic composite warm mix additive on SBS modified asphalt binder

This study investigated the effects of new organic composite warm mix additive on the performance and microstructure of SBS modified asphalt binder. Acmp, as an organic composite warm mix additive, was used to prepare warm mix SBS modified asphalt binders with different contents, and compared and analyzed with Sasobit and Evotherm warm mix additives. The rheological properties of asphalt binders were evaluated by rotational viscometer, dynamic shear rheometer and bending beam rheometer. The effects of the warm mix additives on chemical composition and microstructure of binders were analyzed by fourier transform infrared spectroscopy, thermogravimetric analysis and fluorescence microscope. The results showed that, Acmp had significant viscosity reducing effect, and 6 % Acmp reduced the rotational viscosity of binder by approximately 50 %. Acmp warm mix modified asphalt binder exhibited better low temperature performance compared to Sasobit and Evotherm, but Acmp had negative impact on the high temperature performance. Acmp was mainly composed of light components produced by the cracking of rubber powder and plastic powder, which were mainly short chain alkanes and did not affect the distribution of SBS in binder. These light components were well soluble in asphalt binder to improve its fluidity and were the main components that affected the performance of binders and achieved warm mix effects. Considering the performance of asphalt binder and mixture, Acmp is more suitable for pavements in cold regions, with a recommended dosage of 5 % of asphalt mass. The findings validate the effectiveness of organic composite warm mix additives and contribute to the exploration of more efficient new warm mix technologies.

Effect of nano-modified EVA on the physical and rheological characteristics of SBR modified asphalt binder

The effects of nanoclay-modified ethylene-vinyl acetate (MEVA) on the physical and rheological properties of styrene–butadiene–rubber (SBR)-modified asphalt binder were investigated. MEVA/SBR composite-modified asphalt binders (MESBR) were prepared with 4 % SBR and varying MEVA content. The effect of MEVA on the properties of SBR-modified asphalt binder (SBRMA) was investigated through penetration, softening point, ductility, viscosity, temperature sweep, and frequency sweep tests. Furthermore, multiple stress creep recovery and bending beam rheometer tests were performed to analyse the deformation resistance and low-temperature performance of MESBR. Additionally, the storage stability of MESBR was evaluated through separation tests and fluorescence microscopy. The results indicated that MEVA addition significantly enhanced the physical and rheological properties of SBRMA both before and after ageing. Compared with SBRMA, MESBR exhibited improved deformation and ageing resistance, making it suitable for use under standard traffic loads at temperatures up to 76℃. However, MEVA exhibited a slightly negative impact on the low-temperature performance and storage stability of MESBR. With the addition of 5 % MEVA, MESBR exhibited favourable comprehensive performance and good storage stability.

Effect of microwave and deodorant treatments on long-term aging characteristics of crumb rubber modified asphalt

This research examined and compared the effect of microwave and deodorant treatments on the rheological and microscopic characteristics of crumb rubber modified asphalt (CRMA) after long-term aging. Although the emissions from the asphalt modified by microwave treatment of crumb rubber (CR-micr) or high-alkane alcohol deodorant treatment of crumb rubber (CR-de) are reduced significantly compared with the ordinary CRMA, the research on their rheological and microscopic properties after aging is insufficient (especially for the CRMA with CR-de), which may pose a potential risk to their application in road engineering. To address this issue, this paper first used the rolling thin film oven and pressure aging vessel test to imitate the long-term aging of CRMAs. Then, the rheological properties of aged CRMA samples were evaluated using a dynamic shear rheometer and a bending beam rheometer. Meanwhile, the surface micromorphology, micromechanical characteristics and the chemical functional groups of CRMA samples before and after long-term aging were characterized by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). The results demonstrated that the microwave treatment can enhance the fatigue life of the long-term aged CRMA by approximately 29 % under 8 % CR content and 3 % strain level, while effectively improve the resistance to low-temperature cracking. Meanwhile, after long-term aging, the carbonyl index of CRMA with CR-micr is 36 % lower than that of CRMA with CR-de and 50 % lower than that of ordinary CRMA. The micromechanical modulus of CRMA with CR-micr is also lower than that of CRMA with CR-de and ordinary CRMA. These findings manifest that the microwave treatment can improve the ability of CRMA to resist long-term aging, and the deodorant treatment does not have an adverse effect on this ability.

Evaluating thermal activated coal gangue as alternative filler in asphalt binder using rheological experiments and molecular dynamic simulation

Asphalt mastic, an important raw material in asphalt pavement, is a mixture of asphalt binder and mineral filler. This study utilized coal gangue (CG) as alternative of natural filler in asphalt mastic, which has benefits to recycling solid waste and saving non-renewable resource. In order to achieve performance improvement of CG asphalt mastic (CGAM), thermal activation approach was applied to treat CG particles from 450 ℃ to 900 ℃. Before and after treatment, the surface morphology, mineral components and size distribution were characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and laser particle size analyzer. Meanwhile, the dynamic shear rheometer (DSR) and bending beam rheometer (BBR) experiments were conducted to compare the rheological responses of CGAM at high and low temperatures. Further, the interfacial behavior between asphalt binder and CG filler is simulated by molecular dynamic (MD) method, aiming to explore the interaction mechanism at atomistic scale. Results show that the activated CG possesses a smaller particle size and a rougher surface by comparison in virgin one (i.e., unactivated CG). And the calcination process results in the crystal phase transition of CG and the proportion increase of alkali minerals, contributing to the stronger interaction ability and higher adhesion energy with asphalt binder. Owing to the positive changes of CG during calcination process, the corresponding CGAM exhibits superior deformation resistance property under recycling loads at high temperature and flexural creep ability at low temperature, especially when the calcination temperature rises to 750 ℃.

Tracing the odor source of crumb rubber modified asphalt emissions and evaluating the deodorization effect of attapulgite

Crumb rubber modified asphalt (CRMA) is widely used in road construction due to its excellent performance. However, it generates significant odorous gases during paving. To analyze the odor contribution, both untreated crumb rubber and desulfurized rubber were involved in this study to prepare CRMA and desulfurized rubber modified asphalt (DRMA). Attapulgite was selected as an emission reduction agent to reduce the odorous emissions released from CRMA and DRMA. An indoor fume collection system and gas chromatography-mass spectrometry (GC-MS) analysis were used to trace the odor source and quantify the odorous emissions. A comprehensive olfactory thresholds database for CRMA emissions was further established to evaluate the odor level of various rubberized asphalt binders by using three-point comparative odor bag method, along with known olfactory thresholds of certain compounds reported in the literature. Dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), bending beam rheometer (BBR) and Brookfield viscosity tests were used to analyze the effect of attapulgite on rheological properties of CRMA and DRMA. Results indicated that odor emission rate of CRMA containing 1 %, 3 %, and 5 % attapulgite was decreased by 42.62 %, 63.29 %, and 71.06 %, respectively. Benzothiazole, derived from tire rubber vulcanization accelerator, can be reduced by 60.25 % with 1 % attapulgite, demonstrating excellent performance in terms of reducing target odor emissions. Although DRMA has a lower emission rate than that of conventional CRMA, the addition of 1 % attapulgite can further reduce the odor emission rate of DRMA by 37.92 %. The addition of attapulgite has less impact on the overall performance of CRMA and DRMA. Besides, it was found that attapulgite can reduce the viscosity of rubberized asphalt binders, which is beneficial for rubberized asphalt mixture paving and compaction. Considering odor reduction, performance, and economic factors, the optimal attapulgite content was determined to be 5 % for CRMA and 1 % for DRMA. This approach successfully reduces odorous emissions while maintaining the desirable properties of CRMA, making it a viable solution for environmentally friendly road construction.

Laboratory evaluation of synergistic blending with SBS-modified bitumen and rejuvenator to enhance the performance of recycled bitumen with a high content of RAP materials

Reclaimed asphalt pavement (RAP) stands as a pivotal construction material widely used in asphalt pavement rehabilitation. The prevailing focus and trajectory revolve around increasing the proportion and utility of RAP materials. However, the potential for temperature and fatigue cracking increases with the dosage of RAP materials. In this study, SBS modified bitumen (SBSMB) and four rejuvenators were combined synergistically with aged asphalt to enhance the performances of the recycled bitumen with high RAP content and consequently augment the value of the RAP material, all while ensuring compatibility between the SBSMB and aged base bitumen. Initially, the base bitumen was aged using a pressure aging vessel (PAV) test. Subsequently, a selection of virgin bitumen (VB), SBSMB, and four rejuvenators were utilized to revitalize the aged bitumen. A comprehensive battery of tests, encompassing conventional tests, temperature sweep, frequency sweep, multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and linear amplitude sweep (LAS), were carried out to characterize the rheological properties. Finally, Fourier transform infrared spectroscopy (FTIR) was employed, along with the determination of polystyrene index (IPS) and polybutadiene index (IPB), to evaluate the compatibility between SBSMB and aged base bitumen. The results underscore that the incorporation of SBSMB and rejuvenator comprehensively enhances high-temperature performance and fatigue cracking resistance while effectively reinstating low-temperature cracking resistance. Furthermore, the values of IPS, IPB, and IPS/IPB exhibit an increase with the addition of a rejuvenator, indicating its potential to improve the compatibility between SBSMB and aged base bitumen. Thus, this research proposes a more cost-effective and environmentally sustainable approach to bolstering conventional asphalt pavement performance and grade.

Performance assessment of composite modified bitumen integrated with desulfurized crumb rubber and SBS modifier as waterproofing adhesive layer

Performance of the waterproofing adhesive layer played a critical role for governing duration of bridge deck paving system due to harsh service conditions. To develop a new type of modified bitumen suitable for the layer between bridge deck and overlaid asphalt, this study investigated the performance of composite modified bitumen (CMB) integrated with desulfurized crumb rubber (DCR) and SBS modifier. The influence of DCR and SBS additive on rheological behavior, high-temperature performance, low-temperature cracking resistance, and adhesive performance of CMB was investigated by adopting various experimental tests, which including penetration, ductility, softening point, Brookfield viscosity, dynamic shear rheometer (DSR), bending beam rheometer (BBR), and bonding strength. The high-temperature stiffness and low-temperature flexibility of CMB was improved after composite modification, which in turn contributed to the shear and cracking resistance. The black diagram indicated that the formation of polymer network in the CMB improved the viscous flow resistance and maintained elastic response at high in-service temperature. The bonding strength and moisture stability of the composite bitumen-concrete interface were enhanced, with the properties exceeded the commercial SBS modified bitumen. The CMB binders R18S2 and R18S3 presented good performance and can be used for waterproofing adhesive layer as a substitute of the commercial SBS modified bitumen.

Low-temperature performance and micro-structure of warm mix recycled composite aged asphalt

Given the cold winters in Inner Mongolia, the low-temperature performance of asphalt pavement is one of the key factors affecting the service life of roads. This study focuses on commonly used SBS modified asphalt and investigates the coupling effect of adverse factors such as solar radiation, high temperature, and precipitation on road surface asphalt. The objective is offer insights for improving the applicability and service life of warm mix recycled asphalt in cold regions. By using indoor simulation aging equipment, asphalt subjected to hot oxygen aging, composite water aging, and composite ultraviolet aging was prepared to investigate the low-temperature performance of warm mix recycled asphalt. Additionally, to explore the synergistic effect of new asphalt, regenerant, and warm mix agent on the regeneration of aged asphalt, this study analyzes the low-temperature performance and microstructure changes of recycled asphalt through bending beam rheometer (BBR) test, atomic force microscopy (AFM) test, and infrared spectroscopy (FTIR) test. The results show that as the degree of aging increases, the low-temperature crack resistance performance of asphalt deteriorates. Additionally, after the regeneration of aged asphalt, the damping ratio and dissipation energy ratio of warm mix recycled asphalt slightly enhances compared to hot mix recycled asphalt. Furthermore, the incorporation of a warm mix agent enhances the asphalt’s fluidity, viscosity, surface toughness, and further its low-temperature performance. The AFM test results show that the synergistic effect of warm mix agents and regeneration effectively restores the microstructure and surface roughness of asphalt. Moreover, the warm mix agent improves the dispersion uniformity of the SBS modifier in asphalt, helping prevent the agglomeration of asphalt slurry. Qualitative and quantitative analysis of asphalt through FTIR test demonstrates that the mechanisms of warm mix agents and regeneration on new and aged asphalt are a physical process. New asphalt and regeneration supplement the internal lightweight components of aged asphalt, enabling the restoration of most asphalt without affecting the structure of SBS modified asphalt. This project provides a theoretical basis for the engineering applicability of high content warm mix recycled asphalt (composed of 50 % aged asphalt) in large temperature range areas.

Effects of Impurities and Ageing on the Functional and Rheological Properties of Asphalts with Additives from Recovered and Pyrolysis-Processed Plastics.

This article is a continuation of work on the use of plastic waste (such as PP, PS, LDPE, HDPE, and their mixtures) processed in the proprietary pyrolysis process as asphalt additives. The article carried out detailed tests of the mixes of selected additives with pen-graded bitumen 50/70, taking into account, among others, the influence of impurities and the ratio of PE to PP in the additives as well as short- (RTFOT) and long-term (RTFOT + PAV) ageing. An extensive research program was carried out, including functional and rheological tests in a wide range of temperatures. First, tests of stability and adhesion to various types of aggregates were carried out, demonstrating the usefulness of the proposed additives. Then, the elastic recovery and the impact of technological ageing on penetration, Fraass breaking temperature, and plasticity range were assessed. The same binder mixes were subjected to rheological tests in a wide range of technological and operational temperatures, assessing, among others, viscosity, the norm of the complex shear modulus, elastic recovery and compliance in the MSCR test, and stiffness in the bending beam rheometer. This entire class of tests was carried out for clean samples and those containing impurities, indicating their impact on individual material parameters.

Identification of asphalt binder tests for detecting variations in binder cracking performance

Asphalt binders are vital components in the construction of roadways, and their quality significantly impacts the performance and durability of asphalt mixtures. However, it is possible for binders to exhibit different performance with identical Performance Grade (PG) due to variations in source, refining processes, and modifiers (if any). This paper presents a comprehensive study aimed at identifying candidate tests to detect variances in the quality of the binders in terms of cracking resistance. Eight PG 64–22 asphalt binders were selected and subjected to multiple laboratory tests, including X-ray fluorescence (XRF), Dynamic Shear Rheometer (DSR), Poker chip, and Bending Beam Rheometer (BBR) tests. The binders were then incorporated into asphalt mixtures, and their cracking resistance was evaluated using the IDEAL cracking test (IDEAL-CT) and Overlay test (OT). The study findings revealed that phase angle test, poker chip test, and Glover–Rowe (G–R) parameter test emerged as promising candidates to detect variations in the quality of binders of the same grade based on their cracking resistance. Notably, phase angle and G-R tests, both utilizing DSR, offered valuable supplementary assessments to the traditional PG grading system, proving crucial in evaluating cracking resistance. Furthermore, the poker chip test, an affordable alternative to DSR, demonstrated its effectiveness in evaluating binder quality for cracking performance. In conclusion, the identified candidate tests provide valuable insights into evaluating the quality of asphalt binders. By incorporating these tests into mix design and evaluation processes, engineers can make informed decisions to optimize the performance and durability of asphalt pavements.

Study on the Performance of Asphalt Modified with Bio-Oil, SBS and the Crumb Rubber Particle Size Ratio.

To enhance the properties of SBS and crumb rubber-modified asphalts, four different amounts (5%, 10%, 15%, and 20%) of castor oil were added to crumb rubber-modified asphalts to mitigate the adverse effects of high levels of fine crumb rubber particles on the aging resistance of SBS and crumb rubber-modified asphalt. Initially, a conventional test was conducted to assess the preliminary effects of bio-oil on the high-temperature and anti-aging properties of SBS and crumb rubber-modified asphalt. Subsequently, dynamic shear rheometer and bending beam rheometer tests were employed to evaluate the impact of bio-oil on the high- and low-temperature and anti-fatigue properties of SBS and crumb rubber-modified asphalt. Finally, fluorescence microscopy and Fourier transform infrared spectroscopy were used to examine the micro-dispersion state of the modifier and functional groups in bio-oil, SBS and crumb rubber composite-modified asphalts. The experimental results indicated that bio-oil increased the penetration of SBS and crumb rubber-modified asphalt, decreased the softening point and viscosity, and significantly improved its aging resistance. The addition of bio-oil enhanced the anti-fatigue properties of SBS and crumb rubber-modified asphalt. The optimal amount of added bio-oil was identified. Bio-oil also positively influenced the low-temperature properties of SBS and crumb rubber-modified asphalt. Although the addition of bio-oil had some adverse effects on the asphalt's high-temperature properties, the asphalt mixture modified with bio-oil, SBS, and crumb rubber still exhibited superior high-temperature properties compared to unmodified asphalt. Furthermore, fluorescence microscopy and Fourier transform infrared spectroscopy results demonstrated that bio-oil can be uniformly dispersed in asphalt, forming a more uniform cross-linked structure and thereby enhancing the aging resistance of SBS and crumb rubber-modified asphalt. The modification process involved the physical blending of bio-oil, SBS, and crumb rubber within the asphalt. Comprehensive research confirmed that the addition of bio-oil has a significant and positive role in enhancing the properties of SBS and crumb rubber-modified asphalt with different composite crumb rubber particle size ratios.

Critical analysis of using recycled wax oils in asphalt binder considering exudation effects

The tendency of asphalt to exude oil under certain conditions is often overlooked as a form of aging in asphalt pavement. To better understand the issue of oil exudation in asphalt during long term cold storage, two different oil sources of asphalt binders with recycled wax oils were investigated using the extended bending beam rheometer test (Ex-BBR), double edge notched tension test (DENT), extended Hansen solubility model, and fluorescence and polarizing microscopy. The results of the Ex-BBR and DENT tests demonstrate that the addition of recycled wax oils significantly enhances the low-temperature performance of asphalt. However, the use of fluorescing markers in cooling media indicates that recycled wax oil exudation can lead to ethanol diffusion in the asphalt binder. To further elucidate the factors influencing exudation, a device for accelerating the exudation of asphalt was developed. The research results show that, in addition to the intrinsic properties of asphalt and recycled wax oils, pressure, time, and temperature significantly influence the acceleration of exudation. The primary changes in recycled wax oil exudation occur early on, with the exudation rate decreasing over time. The fluorescent microscope reveals the separation of recycled wax oils as a fluorescent ring. Recycled wax oils alter the internal stability of asphalt, as evidenced by an increase in polarity and hydrogen bonding. This change is expected to impact the compatibility of asphalt binders. The mechanism of these interactions varies significantly depending on the source of the asphalt binder. After accelerated exudation, the three interaction forces representing sensitivity to chemical environments are further reduced.

Effects of TLA on rheological, aging, and chemical performance of SBS modified asphalt

The durability and stability of Styrene-Butadiene-Styrene (SBS) modified asphalt in practical applications have garnered significant attention, with resistance to aging emerging as a pivotal indicator for evaluating performance. This study focuses on the composite modification of SBS-modified asphalt (SBS-MA) using Trinidad Lake asphalt (TLA), resulting in the creation of SBS-MA and three types of SBS/TLA composite modified asphalt (with TLA content at 10 %, 20 % and 30 % of the mass of SBS-MA). To assess the aging resistance, the four modified asphalts underwent prolonged aging for 10 h, 20 h, 30 h and 40 h using the Pressurized Aging Vessel (PAV) test. The macroscopic performance and microscopic characteristics of differently aged modified asphalts were then analyzed through methods such as Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR) and Fourier Transform Infrared Spectroscopy (FTIR). From the perspective of high-temperature performance, the asphalt modified with 10 % SBS exhibits optimal performance indicators during long-term aging processes, with a correlation coefficient reaching up to 99 % in relation to aging time. When the asphalt content exceeds 30 %, it adversely affects the stress sensitivity of SBS-modified asphalt. In terms of fatigue performance analysis, under a 5 % strain condition, the fatigue life of S-30 composite modified asphalt only decreases by 8 %, and TLA mitigates fatigue damage during the aging process of SBS-modified asphalt. Regarding low-temperature performance analysis, when the TLA content surpasses 20 %, it only manifests negative effects on SBS-modified asphalt. From a microscopic perspective, TLA introduces more sulfonyl and carbonyl groups, increasing by 3.6 times and 11 times respectively at a 30 % concentration, thus retarding the oxidation aging reaction of ST-CMA. In summary, this study provides valuable insights and methods for improving the aging resistance of SBS-MA, offering guidance for the application of Trinidad Lake asphalt in road engineering.

Correlation analysis of evaluation methods and indicators for low-temperature performance of epoxy asphalt

Selecting an epoxy asphalt (EA) material with excellent low-temperature performance is a challenging task due to that the traditional test methods and indicators for thermoplastic asphalt may not be appropriate for thermosetting EA, and the binders’ low-temperature performance does not always match that of mixtures. The primary purpose of this study is to determine the appropriate low-temperature evaluation methods and indexes of EA materials and the correlation between the low-temperature performance of EA binder and EA mixture (EAM). First, the low-temperature performance of four EA binders was analyzed using tensile, bending beam rheometer (BBR), and dynamic mechanical analysis (DMA) tests. Then, the low-temperature cracking resistance of the EAMs was evaluated through beam bending and semi-circular bend (SCB) tests. Finally, Pearson correlation analysis was performed separately on the low-temperature indicators of EA binders and EAMs. Moreover, the Grey correlation analysis was employed to determine the correlation between the low-temperature properties of the two. The results showed that the correlation between fracture elongation (ε) and other test indicators was not significant. The multiple indicators of the BBR, such as viscoelastic parameters, viscous deformation ratio (JR), along with the glass transition temperature (Tg) of the DMA, showed consistent evaluation results for the low-temperature performance of the four EA binders. However, the correlation of these indicators with the cracking resistance of the EAM was notably different. The flexural strain energy density of the beam bending test and SCB fracture energies demonstrated excellent correlation. The grey correlation analysis results of these two indicators as reference series were highly similar. Specifically, the novel JR in this study and the Tg exhibited a better correlation with the low-temperature cracking resistance of EAM. These two indicators were preferentially recommended for the evaluation of the low-temperature performance of EA and the prediction of the low-temperature cracking resistance of EAM.

Investigation of Rutting and Low Temperature Cracking Behavior of Reactive Ethylene Terpolymer and Waste Cooking Oil Modified Bitumen

With sustainability being the most crucial issue of recent years, the use of waste materials in bitumen modification is increasing and becoming widespread. In this experimental study, it was aimed to investigate the high- and low-temperature behavior of bitumen samples modified with waste cooking oil (WCO), reactive ethylene terpolymer (RET), and polyphosphoric acid (PPA). Accordingly, the multiple stress creep and recovery (MSCR) test and the bending beam rheometer (BBR) test were conducted. Depending on the increasing WCO ratio, the Jnr,R%,∆T_c,and λ parameters of modified bitumens were examined in detail. It was observed that with increasing WCO ratio,the Jnr value increased, and elastic recovery and stiffness decreased. In addition, it has been determined that this composite-modified bitumen is resistant to heavy traffic loads and has sufficient flexibility at low temperatures.

The influence of rice bran oil and nano-calcium oxide into bitumen as sustainable modifiers

Bio-oils are increasingly used to enhance petroleum bitumen’s intermediate and low-temperature characteristics regarding their economic and environmental benefits. Research has shown a beneficial impact of nanomaterials on altering bitumen’s high-temperature characteristics. The present study uses a mixture of rice bran oil and nano-calcium oxide to improve the performance of bitumen in all three temperature conditions. Rice bran oil was added to pure bitumen at doses of 3, 5, and 7 % relative to the weight of bitumen. The rheological tests (dynamic shear rheometer, multiple stress creep recovery, linear amplitude sweep, and bending beam rheometer) demonstrated that using rice bran oil in bitumen enhanced its performance at intermediate and low-temperatures but declined its performance at high-temperatures. Therefore, to improve the performance at high-temperatures, the bituminous sample containing 5 % rice bran oil was combined with 1, 3, and 5 % nano-calcium oxide, followed by repeating the rheological tests on them. The samples modified with nano-calcium oxide showed increased friction and shear stress, viscosity, and rutting parameters. Besides, the samples exhibited reduced sensitivity to aging compared to the bio-oil samples. However, the non-recoverable creep compliance and percentage of recovery showed improvements. The fatigue life of bio-oil samples decreased after adding nano-calcium oxide. However, the fatigue life remained higher than the base bitumen sample when adding 1 % nano-calcium oxide. Fourier-transform infrared spectroscopy analysis showed that a new chemical reaction occurred due to adding nano-calcium oxide to bitumen containing rice bran oil. Besides, the scanning electron microscope image revealed that the nano-calcium oxide particles are uniformly and homogeneously distributed within the bitumen sample containing 5 % rice bran oil. Consequently, the mix containing 5 % rice bran oil and 3 % nano-calcium oxide increases the resistance against high-temperature failures and improves the low-temperature performance compared to the base bitumen sample.

Morphology characteristics of filler particles and their effects on the low–temperature cracking behavior of asphalt mastics

The article concerned on particle morphology of mineral filler and its impact on mastic cracking property at low temperatures. Limestone and granite fillers with four-sized groups were prepared and further investigated using a simplex-centroid experimental design. The particle morphologies of each filler were captured using a digital image processing. By applying bending beam rheometer tests, mastic cracking behavior was investigated at low temperatures. Results show that compared with granite filler, each limestone filler shows less regular contour shape (except l1), less abundant angularity (except l1, l2, l5 and l17) and surface texture when performed by a simplex-centroid experimental design. The established fractional derivative Burgers model considering creep damage can effectively describe mastic cracking behavior at low temperatures. Composite fractal dimension is the decisively relevant factor with mastic relaxation behavior. Moreover, mastic creep damage is obviously affected by composite morphology characteristics and filler lithology with increasing loading time. All the results are instructive to inform researches of the selection of mineral filler with appropriate particle morphology that will produce asphalt materials with desired performance.

A sustainable rapeseed oil-based bio-additive designed for hard asphalt binders: Performance, environmental, and economic assessment

The inherent properties of hard asphalt binder give it both mechanical and economic benefits, rendering it a naturally advantageous material for preventing permanent deformation at higher temperatures. However, its poor resistance to thermal and fatigue cracking limits its application in the paving industry. This study aimed to improve the low-temperature and fatigue performance of hard asphalt binders by using the newly developed vegetable oil-based sub-epoxidized rapeseed oil (SERO). Two SEROs with epoxidation degree of 49.1% and 98.1% were synthesized through an oxidation reaction, respectively. Subsequently, the microstructural characteristics of SEROs were examined by Fourier transform infrared spectroscopy (FTIR) and Hydrogen nuclear magnetic resonance tests. The anti-oxidative aging properties of SERO modified hard asphalt binders were investigated through the utilization of mass loss and aging index. Additionally, the comprehensive rheological properties of SERO modified hard asphalt binders were explored via dynamic shear rheometer and bending beam rheometer tests. Furthermore, the modification mechanism of SERO on hard asphalt binders was confirmed through the quantitative analysis using the FTIR test. The findings suggested the improvement in anti-volatilization and anti-oxidative aging performance of bio-modified hard asphalt binders, which was positively related to the epoxidation degree of SERO. A notable softening effect of SERO on the hard asphalt binders was observed, which enhanced their resistance to thermal and fatigue cracking at lower and intermediate temperatures. The epoxy groups within SERO engaged in ring-opening reactions, forming a new oxygen bridge bond by combining with the unsaturated double bond presented in the asphalt. Consequently, this process resulted in the formation of cross-linked structures within bio-modified hard asphalt binders, thereby enhancing the elasticity. Notably, this phenomenon was most conspicuous in the SERO-H modified 50# binder. Finally, the environmental and economic assessment of SERO modified hard asphalt binders were conducted by the techno-economic method and the emission factors technique. The data revealed that the production of one ton of SERO modified hard asphalt binders could reduce the production costs by about 30%, energy consumption and CO2 emissions by around 20% in contrast to styrene–butadiene–styrene block copolymer modified asphalt binders. Hence, the substantial economic and environmental advantages make SERO an attractive bio-renewable additive for sustainable pavements.

Effect of waste engine oil and warm mix additive on the physical, rheological, and short-term aging attributes of Styrene–Butadiene Rubber-modified asphalt binders

Styrene-butadiene rubber (SBR) latex is used widely to increase the low-temperature resistance of asphalt binders. However, the high content of butadiene copolymer in SBR-treated asphalt causes oxidation and aging. Furthermore, following the SBR modification, the compatibility and thermal storage stability of SBR-modified asphalt is not satisfactory. Therefore, the best approach to improve the quality of short-term aged SBR-modified asphalt is to lower the manufacturing temperatures of the SBR-modified asphalt mixture. In this study, to reduce the preparation temperatures of SBR-modified asphalt mixes and improve their performance after short-term aging, several additives i.e., waste engine oil (WEO), warm mix agent i.e., ZycoTherm, and WEO/ZycoTherm combination (WEO+ ZycoTherm) were selected. The rheological properties and aging performance of binder samples were evaluated through the rational viscosity, dynamic shear rheometer, bending beam rheometer and Fourier transform infrared spectroscopy tests. The results showed that adding WEO together with ZycoTherm into an SBR-modified binder contributed to reducing the compaction and mixing temperatures. The chemical analysis showed that the three additives i.e., WEO, ZycoTherm, and ZycoTherm/WEO declined the aromaticity and chemical aging indicators of aged SBR-modified binders. Furthermore, it was demonstrated that both the ZycoTherm and WEO/ZycoTherm improved the asphalt resistance to rutting at elevated temperatures in both conditions i.e., before and after short-term aging. In addition, the findings revealed ZycoTherm /WEO compound yielded the best performance to improve the minimal-temperature cracking resistance of the SBR-modified binder, resulting in lower short-term aging temperatures. In summary, this study highlights the necessity of lowering preparation temperatures in asphalt mixes containing SBR to enhance binder resistance to rutting and cracking and reduce susceptibility to oxidation during short-term aging.