Asphalt Rubber Research Articles

Research on Low-Cost High-Viscosity Asphalt and Its Performance for Porous Asphalt Pavement.

To develop a cost-effective, high-viscosity asphalt for porous asphalt pavement, we utilized SBS, tackifier, and solubilizer as the main raw materials, identified the optimal composition through an orthogonal experiment of three factors and three levels, and prepared a low-cost high-viscosity asphalt. We compared its conventional and rheological properties against those of rubber asphalt, SBS modified asphalt, and matrix asphalt, employing fluorescence microscopy and Fourier transform infrared spectroscopy for microstructural analysis. The results indicate that the optimal formula composition for high-viscosity asphalt was 4-5% styrene-butadiene-styrene (SBS) + 1-2% tackifier +0-3% solubilizer +0.15% stabilizer. The components evenly dispersed and the performances were enhanced with chemical and physical modification. Compared with SBS modified asphalt, rubber asphalt, and matrix asphalt, the softening point, 5 °C ductility, and 60 °C dynamic viscosity of high-viscosity asphalt were significantly improved, while the 175 °C Brookfield viscosity was equivalent to SBS modified asphalt. In particular, the 60 °C dynamic viscosity reaches 383,180 Pa·s. Rheological tests indicate that the high- and low-temperature grade of high-viscosity asphalt reaches 88-18 °C, and that high-viscosity asphalt has the best high-temperature resistance to permanent deformation and low-temperature resistance to cracking. It can save about 30% cost compared to commercially available high-viscosity asphalt, which is conducive to the promotion and application of porous asphalt pavement.

Multiscale enhancement mechanism of low-temperature performance for degraded recycled waste rubber asphalt binders: MD simulation and microscopic investigation

Desulfurization and degradation are important processes to facilitate the storage of waste rubber asphalt and improve its utilization. However, this process is extremely complex and the mechanisms underlying the resulting performance enhancement remain unclear. This study aims to investigate the multiscale mechanism of rubber degradation and its impact on the low-temperature performance of degraded rubber modified asphalt (DRMA) binder through differential scanning calorimetry (DSC), bending beam rheometer (BBR), fluorescence microscopy (FM) and Fourier transform infrared spectroscopy (FTIR) tests and molecular dynamics (MD) simulations. The results showed that as the degradation of rubber powder deepens, lightweight components decomposed from the rubber are more easily dissolved into the virgin asphalt, thus improving its dispersion. In addition, the small molecular structure after rubber degradation penetrates and fills the aggregation space between asphalt molecules, effectively increasing the molecular activity of asphalt, thus enhancing the low-temperature performance of asphalt.

Application of fume silica nanoparticles to improve high-temperature rheological performance of terminal blend rubberized asphalt

This study aims to evaluate the impact of fume silica nanoparticles (FSNPs) on the high-temperature rheological properties of terminal blend rubberized asphalt (TBRA). In this study, FSNPs were utilized to modify TBRA asphalt with three different CR contents (30%, 40%, 50%). The micro-morphology of FSNPs was observed through Scanning Electron Microscopy (SEM) experiments. The effects of FSNPs on the high-temperature rheological properties of TBRA were assessed using temperature sweep tests, Multiple Stress Creep Recovery (MSCR), and rotational viscosity tests. Furthermore, the influence of FSNPs on the chemical and thermal properties of TBRA was analyzed through Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) tests. Rheological tests and SEM results indicate that FSNPs can effectively enhance the high-temperature elasticity, fatigue resistance, and deformation resistance of TBRA binders. This improvement is attributed to the unique branched network structure of FSNPs, which plays a pivotal role in enhancing the elasticity within the TBRA asphalt matrix. Additionally, the degradation of TBRA's low-temperature performance due to FSNPs is minimal. Considering the optimal viscosity for FSPN-modified TBRA, recommended ratios are: TB30/6%, TB40/4%, and TB50/2%. FTIR and TGA results demonstrate that the modification of TBRA by FSNPs is primarily physical blending, and the addition of FSNPs enhances the thermal stability of TBRA.

Performance evaluation of SBS-modified asphalt mixtures incorporating waste tire rubber and HDPE

Based on the functional complementarity of waste tire rubber (WTR) and waste high-density polyethylene (HDPE) in asphalt, this study presents a novel approach that simultaneously utilizes WTR and HDPE for modification and substitution of styrene-butadiene-styrene (SBS) modified asphalt. Through experiments on three major indicators, the dosage ratios of the three polymers are scientifically designed using the response surface methodology, and four different ratios of SBS-HDPE-WTR are selected to prepare modified asphalt mixtures. Performance evaluations are conducted on various pavement properties, including high-temperature stability, low-temperature crack resistance, water stability, fatigue resistance, and aging resistance, by comparing them to the reference 4% SBS-modified asphalt mixture. The results demonstrate that the addition of WTR significantly improves the elastic properties and fatigue resistance of the mixture, while the addition of HDPE enhances its high-temperature stability and aging resistance. The SBS-HDPE-WTR asphalt mixtures, designed with appropriate ratios, exhibit superior high-temperature stability, low-temperature crack resistance, and fatigue resistance. Therefore, the use of these waste materials in asphalt mixtures offers a sustainable and environmentally friendly solution for the construction industry.

Secondary degradation of bio-oil degraded crumb rubber and preparation of stable degraded crumb rubber modified asphalt

Using bio-oil to desulfurize and degrade crumb rubber (CR) significantly enhances the compatibility between CR and asphalt, improving the workability of CR-modified asphalt and providing environmental and economic benefits. However, the secondary degradation of bio-oil degraded crumb rubber (ODR) in asphalt hinders the stability of ODR-modified asphalt. To optimize the mechanical performance of ODR-modified asphalt, the secondary degradation behaviors of ODR were investigated. The degree of CR degradation was determined by solubility testing, while the rheological properties and chemical structures of ODR-modified asphalt were characterized through rotational viscometer, dynamic shear rheometer, bending beam rheometer, and Fourier transform infrared spectrometer. The processes for preparing stable ODR modifier and ODR-modified asphalt were proposed to mitigate the damage caused by bio-oil and degraded CR to the high temperature mechanical properties of asphalt. The results show that at lower processing temperatures for ODR-modified asphalt, the volatilization of light components is predominant, while higher processing temperatures prompt secondary degradation of ODR. By stirring at 280°C for 2 hours to acquire moderately degraded CR, and then concentrating it at 220°C for 2 hours, a stable ODR less susceptible to secondary degradation can be obtained. The workability, temperature sensitivity, and low temperature cracking resistance of stable ODR-modified asphalt improve significantly. The reduction of ester group and increase in aromaticity restore the high temperature deformation resistance of ODR-modified asphalt. Further, the inclusion of composite SBS extends the range of rheological properties in ODR-modified asphalt, bolstering the application potential of ODR in asphalt pavement.

Analysis of potential incorporation of waste into asphalt pavements

The incorporation of waste materials into asphalt pavements has gained increasing attention as a sustainable and environmentally responsible approach to road construction and maintenance. This study examines the performance of asphalt mixtures incorporating foliated quartzite waste and rubber asphalt for road pavements. Despite deviations in certain parameters from recommended standards, such as sand equivalent and Los Angeles abrasion, alternative materials like quartzite waste can still be viable for asphalt mixtures if they ensure structural integrity. Mechanical tests reveal that the asphalt rubber and quartzite waste mixture exhibit superior tensile strength and resilience modulus compared to reference mixtures, suggesting enhanced load-bearing capacity and resistance to deformation. This study underscores the versatility of utilizing materials like quartzite waste and rubber from scrap tires in road pavement applications, advocating for further exploration of their suitability, particularly in regions with extensive road networks and diverse environmental conditions. Furthermore, the adoption of these materials promotes environmental sustainability by mitigating environmental damage and reducing the consumption of conventional aggregates in pavement construction, thereby fostering a more sustainable approach to infrastructure development.

Experimental Research on the Anti-Reflection Crack Performance of Basalt Fiber Modified Rubber Asphalt Stress-Absorbing Layer.

Reflection cracks are one of the most common problems in semi-rigid base pavement. Setting a stress absorption layer can effectively delay the occurrence of reflection cracks, but further improvement is still needed in its interlayer bonding performance and anti-reflection crack performance. Considering the excellent crack resistance of basalt fibers and the good elastic recovery ability of rubber asphalt, it is considered worthwhile to incorporate them into traditional stress absorption layers to improve performance. To simulate the actual pavement layer effect, composite specimens consisting of a cement-stabilized macadam base + basalt fiber rubber asphalt stress-absorbing layer + AC-20 asphalt mixture surface layer were prepared to evaluate their performance through interlayer direct shear tests, interlayer tensile tests, three-point bending tests, and overlay tests (OTs). To determine the optimal fiber blending combination, four fiber lengths (3 cm, 6 cm, 9 cm, 12 cm) and four fiber proportions (120 g/m2, 140 g/m2, 160 g/m2, 180 g/m2) were selected respectively. The specific effects of basalt fibers with different lengths and dosages were analyzed. The results show that compared with the absence of fibers, the improvement of interlayer bonding performance of rubber asphalt with basalt fibers is not significant, and it has certain limitations; however, the improvement of anti-reflective crack performance is significant, with an increase of up to 305.5%. This indicates that the network structure formed by basalt fibers and rubber asphalt stress absorption layer can effectively absorb and disperse external loads, causing an excellent crack resistance effect. Meanwhile, the results indicate that the main factor affecting its interlayer bonding strength and anti-reflective crack performance is the fiber content. Based on the comprehensive analysis of the performance and economy of the stress absorption layer of basalt fiber rubber asphalt, the optimal fiber parameter combination recommended is as fiber length 9 cm and fiber content 160 g/m2. These results can provide a reference for the design and performance evaluation of basalt fiber rubber asphalt stress absorption layer, and have certain application value.

Ultrasound-assisted preparation of crumb rubber modified asphalt: Characterization and molecular dynamics simulation

The traditional method of crumb rubber modified asphalt (CRMA) preparation can improve the stability but is not conducive to cleaner production. From the perspective of process optimization, ultrasound is introduced into the crumb rubber modified asphalt preparation process, and the high temperature, high pressure and high energy accompanied by the cavitation effect are used to generate free radical triggering chemical effects at the two-phase interface between crumb rubber and asphalt. In this paper, the influence of ultrasound on the compatibility and stability of crumb rubber modified asphalt system was evaluated by combining experiment and molecular dynamics simulation. An experimental platform for ultrasound-assisted preparation of crumb rubber modified asphalt was established. The effects of ultrasonic on the physical properties of asphalt and crumb rubber modified asphalt were studied through Brookfield viscosity test, thin film oven aging test and Fourier infrared spectroscopy. The base, aged, and ultrasonically treated asphalt samples were simulated using molecular dynamics, and various parameters such as Cohesive Energy Density (CED), Mean Square Displacement (MSD), and Free Volume Fraction (FFV) of asphalt and its components were calculated and analyzed. The results showed that under the ultrasonic-assisted preparation, the agglomeration phenomenon of rubber particles is weakened, the particle size is reduced, the penetration degree is reduced, and the compatibility between rubber and asphalt is improved. Under the action of ultrasonic, the MSD and diffusion coefficient of crumb rubber modified asphalt are much higher than other kinds of asphalt, the dipole moment is increased, and the molecular motion range is wider. This indicates that the diffusion ability of crumb rubber modified asphalt is significantly enhanced under the external force of ultrasonic simulation. The molecular bonds of crumb rubber modified asphalt changes greatly, the energy decreases obviously, and the system stability increases. In conclusion, ultrasonic action on crumb rubber modified asphalt preparation is a green and effective way to improve system stability and compatibility.

Automating the determination of low-temperature fracture resistance curves of normal and rubberized asphalt concrete in single-edge notched beam tests using convolutional neural networks

As materials undergo large-scale yielding or exhibit large sizes of fracture process zone in the crack tip region, multi-parameter fracture concepts should be employed to describe the complex crack-tip stress-strain fields. Fracture resistance curves (R-curves) are an established tool in characterizing the entire fracture process of such materials. However, for complex materials such as bituminous mixtures, the development of these curves is subject to experimental and computational intricacies. In this research, a framework is developed to automate the construction of R-curves for normal and rubberized asphalt concrete (AC) mixtures. AC mixtures are produced using PG58–22 and PG58–28 binders. Limestone and siliceous aggregates are used, and three binder contents are considered for the mixtures. Single-edge notched beam (SE(B)) fracture testing is conducted on AC beams with two different notch patterns. A convolutional neural network (CNN) model is developed and trained over 1260 test images with varying temperatures, notch geometries, and setups. The CNN model was used to detect the growing crack on the beam surface and each crack-detected image was sent to an image processing framework to measure the crack length. Crack extension increments were calculated and synchronized with test time and magnitude of load, load-line displacement, and cumulative fracture energy, and the R-curve could be constructed. A training accuracy of 0.91 was obtained for the model and a loss of below 0.10 as a result of a hyperparameter tuning indicating reliable classifications by the CNN architecture. The R-curves showed desirable agreement for control mixtures at temperatures of 0 °C and −15 °C. As the mixtures are rubberized, the R-curves showed favorable agreement in the crack blunting phase, transition zone, as well as the unstable propagation phase at −20 °C. Cohesive energy magnitudes were compared for the two methods with a Pearson coefficient of 0.81 while fracture rate and fracture energy magnitudes showed favorably close magnitudes with coefficients of 0.89 and 0.98 respectively.

Mechanistic-empirical pavement design to include mechanical performance of rubberized asphalt pavements in the use stage of life cycle assessment

The use phase of road pavements includes fuel consumption, urban heat island, and leaching. Life cycle assessment (LCA) often omits the use phase for its complexity. The use phase should also consider the durability of the asphalt mixtures. This study used the Mechanistic-Empirical Pavement Design to include the durability of five asphalt mixtures (control, styrene-butadiene-styrene - SBS, polymer coated rubber - PCR dry and wet, and devulcanized rubber - DVR) in the LCA of 1-mile road pavement over 50 years. Considering only the impact of the mixture production, the control mix had a carbon footprint 12.9 % lower than the other mixtures. When including the durability, the control mixture's carbon footprint was 69 % and 84 % higher than SBS and PCR dry mix, respectively. This study showed the importance of including the mechanical performance of the asphalt mixtures to better evaluate the environmental impact of road pavements over the service life.

Thermal effects on rheological characteristics and its evolution mechanism of bio-modified rubberized asphalt for sustainable road system: A focus on rubber particle size

Bio-modified rubberized asphalt (BMR) has been acclaimed for its superior pavement performance and eco-friendliness, which can promote the sustainability of road systems. However, its rheological properties, intimately tied to crumb rubber (CR) particle size, display variability during thermal storage. This study probed the effect of CR particle size on BMR's rheological attributes under thermal conditions. BMRs were prepared using varied CR particle sizes, thermally conditioned over a span of up to 10 h, and then tested for rheological properties. Our findings illustrate particle size's pivotal role in CR swelling, degradation, and asphalt aging mechanisms during thermal conditioning, consequently affecting various BMR characteristics. Large CR particles displayed slower swelling rates, with secondary swelling observed. The CR's micro-skeleton within asphalt phase amplified asphalt's elasticity recovery, causing an increased rutting factor and complex viscosity. In contrast, stress concentration due to CR particles curtailed the fatigue life of BMR. With smaller CR particles, both elastic response and viscosity of BMR diminished due to CR's devulcanization and depolymerization during thermal conditioning. However, substances released during CR degradation altered the asphalt composition, bolstering BMR's fatigue resistance. During thermal process, asphalt oxidation resulted in increased stiffness, thereby degrading BMR's rheological properties. It is beneficial for CR of 40 mesh or coarser to extend the breeding time to stabilize its performance, whereas for asphalt prepared with 60 mesh or finer CR, it should be used as soon as possible after preparation to prevent a significant performance degradation. In summary, managing particle size and thermal conditioning time is crucial in preserving BMR's optimal rheological properties.

The Influence of Immertion on Marshall Parameters and Residual Strength Index of Rubber Asphalt Mixture

The bad drainage system in the road pavement area also causes the road body to be submerged in water for quite a long time, causing the bond between the asphalt and aggregate to loosen, resulting in decreased service life. Developments in the field of road construction have now implemented many innovative ideas, one of which is namely the use of rubber asphalt with asphalt containing natural rubber which has 1.5 to 2 times the strength compared to conventional asphalt. In evaluating the performance of an asphalt mixture, especially the AC-WC Wear layer mixture, it can be analyzed using the Marshall test method by taking into account the conditions being tested, namely the test object being immersion in water or continuously flooded with water. The method used in this research is an experiment with treatment conditions for AC-WC rubber asphalt mixture specimens which are continuously immersion in water for 1 day, 2 days and 3 days. The research results showed that there was an increase in the VMA, VIM, and flow parameters, while the VFB, stability, and Residual Strength Index parameters decreased with increasing soaking time. Based on the research results, it can be concluded that although there is an influence on the performance of the asphalt mixture with the use of rubber asphalt, the decrease that occurs is not too large and is still within the required specifications.

Foamed waste oil-activated rubberized asphalt binder: A sustainable recycling approach for improving foaming effect and performance

This study prepared foamed waste oil-activated rubberized asphalt (ORA) by activating crumb rubber (CR) with waste vegetable oil (WVO) to address the issue of undesirable foaming effect. Optimal foaming parameters for different rubberized asphalt were determined based on foaming characteristic experiments. Furthermore, rheological properties, fatigue resistance, and adhesion performance of various unfoamed or foamed rubberized asphalt were evaluated through dynamic shear rheometer, bending beam rheometer, pull-out tests. Finally, the analytic hierarchy process was utilized to select the optimum foamed rubberized asphalt. The results show that foaming pressure has a great influence on rubberized asphalt foaming effect, and is recommended at 300 kPa. Compared to conventional rubberized asphalt whether foamed or not, with the increase of activation degree, low-temperature performance, and fatigue resistance of ORA are significantly ameliorated, and the adhesion property of ORA first increases and then decreases, but detrimental to high-temperature performance. The foaming process and foaming agent addition are conducive to low-temperature performance but unfavorable to fatigue resistance and high-temperature property, and have little effect on adhesion performance. ORA (mass ratio of WVO to CR is 1:5) with foaming agent is determined as the optimum selection.

Development of dynamic shear-rheology-based method to improve evaluation of swelling degree of recycled crumb rubber in asphalt rubber

Inappropriate disposal of substantial scrap tires has become an unavoidable and imminent environmental concern. Asphalt rubber (AR) facilitates the value-added recycling of scrap tires into eco-friendly and durable pavement, showcasing immense potential for pollution alleviation and resource conservation. In preparing AR, the swelling effect of rubber plays a dominant role in the gel-like network formation and performance enhancement of the modified asphalt. Accordingly, it is crucial to accurately evaluate the rubber swelling degree for guiding AR preparation and mixture design. Existing research mainly relies on measuring the volume of expanded rubber particles to assess the rubber swelling degree, which requires sophisticated instruments or a cumbersome process of extracting the crumb rubber. In this study, a method was proposed to conveniently evaluate the swelling degree of crumb rubber based on the dynamic shear rheological indicators. Firstly, the base asphalt was mixed with crumb rubber at different levels of time to prepare AR binders with varying swelling degrees. The mechanical properties (i.e., elastic recovery) and physical properties (i.e., volume expansion) were measured and analyzed to investigate the impacts of swelling time on AR properties. Secondly, the rheological properties of AR with different swelling degrees were measured via temperature sweep (TS) test, multiple stress creep recovery (MSCR) test, and linear amplitude sweep (LAS) test. Thirdly, the particle effect (PE) and interaction effect (IE) values were calculated, and the swelling degrees were determined based on the variations of PE values. Relationships between swelling degrees and PE-related indicators were established to facilitate the development of the new evaluation method. Finally, the swelling degrees evaluated by the newly developed method were compared with volume expansion to validate its reliability. The results from different rheology tests were also used to verify the feasibility of the proposed method, and the prediction of swelling degree against the swelling time was established. The findings of this research provide references for evaluating the swelling degree of crumb rubber conveniently and accurately.

A new method and first results for comparing emissions of fumes during construction of asphalt surfaces

A novel laboratory methodology for analysing hot asphalt fumes from various paving materials is presented and evaluated. This method facilitates comparative assessments, aiming to enhance occupational safety for asphalt workers and ensure safe implementation of new paving materials. Comparative analyses of emissions to air were conducted on standard asphalt and rubber-modified asphalt at different temperatures. The temperature significantly influences PAH emissions. Rubber-modified asphalt demonstrated higher PAH emissions at equivalent temperatures compared to standard asphalt, predominantly naphthalene. Even heavier PAHs as benzo(a)pyrene were occasionally high. Notably, at recommended working temperatures the standard asphalt resulted in higher emissions, comprising heavier PAHs compared to rubber asphalt.

Mechanical, economic, and environmental assessment of recycling reclaimed asphalt rubber pavement using different rejuvenation schemes

Asphalt rubber (AR) is a prevailing sustainable paving material, but the recycling of reclaimed asphalt rubber pavement (RARP) faces the lack of proper rejuvenation strategies and the uncertainties in its economic and environmental values. To fill these gaps, this study assesses the comprehensive performance of RARP-included mixtures using different rejuvenation schemes through mechanical tests, life cycle cost analysis (LCCA), and life cycle assessment. The addition of rejuvenators increased the rutting depth of RARP mixture but their effects on the cracking resistance varied from different types of rejuvenators. The supplement of swollen rubber content was more effective in improving the cracking and aging resistances. Recycling 40 % of RARP into new AR mixture can save 24.5 % of greenhouse gas (GHG) emissions and 35 % of cost within the geographic scope of Hong Kong. The use of rejuvenator increased the GHG emission and cost, while incorporating extra rubber could further reduce the cost.

Simulation of inhibition and targeted adsorption of rubberized asphalt VOCs by UiO-66 based on molecular dynamics

The adsorption kinetics and molecular dynamics were modeled based on the structure-assembled technique of MOFs, conjugate bonding and targeted adsorption of characteristic pollutants. The mechanism of interaction between UiO-66 and rubber-modified asphalt (RMA) was simulated. The adsorption characteristics between UiO-66 and five class I carcinogens, high concentration VOCs components were simulated by Sorption module. The conjugate bonding and targeting adsorption mechanism between UiO-66 on VOCs was elucidated by combining the GC-MS analysis data. The results were showed that the interaction between UiO-66 and rubberized asphalt was influenced by the number of molecules, contact area, spatial site resistance, and active groups. The content of UiO-66 should be controlled below 3.31 %. The small size of vinyl chloride molecules made it easier to enter the pore structure of UiO-66 with a maximum inhibition rate of 91.75 %. The 1,2-dichloropropane has a large molecular size, spatial site resistance, non-conjugation effect, and the smallest adsorption amount of 72.2 %. The total concentration of VOCs was decreased from 726.38 mg/cm3 to 166.12 mg/cm3, a reduction of 77.13 %. The adsorption of UiO-66 on VOCs molecules was affected by molecular size, carbon chain length, conjugation effect, polarity and other factors. VOCs and UiO-66 form a p-d, d-d π conjugation effect based on the conjugated structure, targeting adsorption within the benzene ring of the organic framework.

Effect of microwave pretreatment on characteristics of asphalt binders modified with scrap non-tire automotive rubber and waste derived pyrolytic oils after prolonged thermal storage

The use of waste automotive rubber and pyrolytic products has recently gained interest in asphalt binder modification, and it also presents an appealing solution towards waste re-utilization and sustainable asphalt binder modification. Further, composite modification of asphalt binders is now often attempted to achieve a wider range of benefits in the asphalt binder performance through the modifiers. For the petroleum crude-based asphalt binders after their modification with different additives, viz. polymers, rubbers, and oils, the phase separation behavior, usually assessed in terms of storage stability, plays a very important and crucial role in its long-term performance. A modified asphalt binder must possess adequate storage stability to assure homogeneity during storage and hauling at elevated temperatures to achieve the desired performance after construction. The present study firstly evaluated the long-term phase separation behavior/storage stability of asphalt binders modified with waste non-tire rubber granules (ethylene-propylene-diene monomer (EPDM) type) alone and then for composite rubberized asphalt binders formulated with EPDM rubber along with tire pyrolytic oil (TPO) and plastic pyrolytic oil (PPO) after microwave pretreatment. To assess the standard and the long-term phase separation behavior in terms of storage stability, formulated rubberized asphalt binders were subjected to thermal storage at two different scenarios: (a) for 2 and 4 days at163 °C, and (b) for 2, 4, 7, 10, and 14 days at 135 °C. The phase separation behavior and performance of rubberized asphalts post long-term storage were evaluated in terms of chemo-rheological, microstructural, and rubber dissolution tests. A total of 28 asphalt binders with variable modification and thermal storage periods were characterized and evaluated. Both storage temperature and duration were found to play a critical role in dictating the storage stability and chemo-rheological performance of the rubberized asphalts, and the prolonged storage stability of rubberized binders correlates well with their rutting and fatigue performance. The pretreatment of rubber granules with pyrolysis oils using microwave irradiation facilitated the achievement of a composite modified asphalt binder with good storage stability and rheological performance.

Effect of Latex Rubber as Asphalt Additive to the Characteristics of AC-WC Mixture

Quality improvement can be achieved by making innovations in the development of rubber asphalt material. This research was conducted to determine the effect of adding natural rubber as an additive to the wear-resistant Laston mixture (AC-WC). This study made 33 total samples, which were divided into 18 conventional asphalt mixtures and 15 rubber asphalt mixtures, with normal asphalt variations ranging from 5.5% - 8% and for rubber with variations of 5% - 7% of optimum asphalt weight, respectively each with an interval (0.5 %). It was mixed using a wet process. Based on the 2018 General Highways Specifications, Optimum Asphalt Content (OAC) was obtained at 7.5% and Optimum Rubber Content (ORC) at 6%. The test results for the stability and melting values of normal asphalt were 1786.22 kg and 3.56 mm, while the tests for the stability and melting values for rubber asphalt were 1181.22 kg and 3.6 mm. It can be interpreted that adding this rubber content increases the stability of the value 2x greater than the point where the stability value falls on the normal asphalt content variation of 8%.

Analysis of Mechanical Response of Epoxy Asphalt-Repaired Pavement in Pothole Interface on Steel Bridge Deck under Coupled Temperature-Dynamic Loading

The persistence of pothole maintenance represents an enduring challenge. Past studies have largely concentrated on the materials and techniques used for remediation, with a lack of attention given to the pothole interface. This paper employed epoxy asphalt rubber (EAR-10) as the repair material, exploring the impact of coupled temperature-dynamic loading on the mechanical response of the interface. Finite element modelling (FEM), adopting the viscoelastic characteristics of EAR-10, was deployed to investigate the mechanical response of the interface under three temperature service conditions high, medium, and low when a dynamic load traversed the pothole. The stress variations in the interface at various inclinations and thicknesses of the repair blocks were also studied. In addition, the comparative analysis of high-temperature rut resistance for powdered rubber composite-modified asphalt and SBS modified asphalt was conducted via the multiple stress examination in terms of its high-temperature resilience, resistance to moisture-induced damage, and fatigue life by employing the asphalt mixture rutting test, low-temperature bending test on small beams, and the water immersion Marshall stability test, respectively. The repair efficacy of EAR-10 was appraised through post-repair water immersion rutting tests and bending tests on composite structural small beams. The results indicated that incorporating coupled temperature-dynamic loading led to a considerable increase in stress, particularly under low-temperature service conditions. An inclination angle of 30 degrees was found to be optimal for the interface. The research methodology presented here is pertinent to guiding the pothole repair in the steel bridge pavement, ensuring the strength and durability of the interface rivals that of newly constructed layers.