Low-temperature Cracking Research Articles

Performance Evaluation of Asphalt and Asphalt Mixtures Modified by Fuel-Resistant Admixture

In the course of asphalt pavement usage, exposure to fuel infiltration accelerates particle detachment, leading to the occurrence of problems such as looseness and peeling. The aim of this study was to comprehensively evaluate the impact of a fuel-resistant modifier (FRM; 1%, 3%, 5%, 7%) on the performance of asphalt and asphalt mixture. Conventional physical tests and high–low temperature rheological tests were conducted on the fuel-resistant modified asphalt (FRMA). The results indicate that, with increased FRM content, the penetration and ductility of FRMA decreased, while the softening point increased. The high-temperature performance improved, but the low-temperature ductility declined. High–low temperature rheological test results demonstrate that the addition of FRM significantly enhanced the asphalt’s shear deformation resistance. A moderate amount of FRM modification improved the asphalt’s low-temperature crack resistance, but excessive FRM resulted in reduced flexibility. In addition, fuel-resistant modified asphalt mixture (FRMAM) specimens were prepared and evaluated for performance. In comparison to the base asphalt, FRM modification enhanced the resistance to oil erosion and peeling as well as the Marshall stability of asphalt mixtures. It reduced the scattering loss caused by fuel dissolution and improved both low-temperature indirect tensile (IDT) strength and high-temperature shear strength. A low content of FRM effectively reduced the sensitivity of asphalt mixtures to fuel infiltration, thus enhancing their road performance.

Evaluation method of modification effect of direct-to-plant SBS modifier on asphalt

To accurately evaluate the modification effect of direct-to-plant styrene–butadiene–styrene block copolymer (SBS) modifier on asphalt, a collection method for direct-to-plant SBS-modified asphalt was proposed in this paper, the qualitative and quantitative evaluation index system was established, and the feasibility of quantitative evaluation based on fluorescence microscopy images and visual inspection of the mixing effect was evaluated, the feasibility of quantitative evaluation indicators was also verified based on the asphalt indicators, rheological properties, and asphalt mixtures's pavement performances. The research results indicate that based on fluorescence microscopy images, by observing the distribution and swelling state of direct-to-plant SBS modifiers can qualitatively evaluate the modification effect of direct-to-plant SBS modifiers on asphalt. Based on the visual inspection of the mixing effect, observe the size and quantity of unmelted particles, determine the melting state of the direct-to-plant SBS modifier, and its modification effect on asphalt can be qualitatively evaluated. For the same direct-to-plant SBS-modified asphalt, the percentage of rotation viscosity between direct-to-plant SBS-modified asphalt and traditional SBS-modified asphalt at 135 ℃ (DAη(135℃)) and discrete coefficient of 135 ℃ rotational viscosity of direct-to-plant SBS-modified asphalt (CVη(135℃)) exhibit a linear relationship with direct-to-plant SBS-modified asphalt's penetration, softening point, and ductility, the smaller the CVη(135℃), the greater the DAη(135℃). The smaller the CVη(135℃) (the larger the DAη(135℃)), the larger the dynamic shear modulus (G*), the smaller the phase angle (δ), and the larger the rutting factor (G*/sinδ) at the same scanning temperature. The relationship between CVη(135℃) (DAη(135℃)) and direct-to-plant SBS modifier on the main technical indicators and rheological performance indicators of asphalt is relatively stable. There is a clear relationship between CVη(135℃) (DAη(135℃)) and the high-temperature stability, low-temperature crack resistance, and water stability of direct-to-plant SBS-modified asphalt mixture, all of which show that as CVη(135℃) decreases (DAη(135℃) increases), the pavement performances improve.

Design and evaluation of semi self-compacting cold mix polyurethane mixture for steel bridge deck pavement

To enhance the environmental sustainability and pavement performance of steel bridge deck paving, a novel semi self-compacting cold mix polyurethane mixture (CMPU-10) for steel bridge deck paving was specifically designed and evaluated. Herein, this study presents the first comprehensive documentation of the research process involved in the mix design of CMPU-10. Initially, based on the theory of maximum density curve, a gradation with a Talbot index (n) of 0.40 was identified as the preliminary gradation for designing CMPU-10 by void ratio, compressive strength and slump tests. Subsequently, the aggregate grade-by-grade filling test revealed the critical influence of sieve sizes (0.075 mm, 0.6 mm, and 2.36 mm) on the mixture dense degree. From these findings, an in-depth analysis of the effects of aggregate passage under the key sieve on the degree of mixture density, compressive strengths, and flow properties led to the determination of the gradation range of CMPU-10. The optimum binder-aggregate ratio for the median gradation was determined to be 9.2%. Finally, wheel tracking, semi-circular bending (SCB) and freeze-thaw splitting tests showed that the designed CMPU-10 exhibits superior high-temperature stability performance, low-temperature cracking resistance and moisture susceptibility compared to the TAF epoxy asphalt mixture (EA-10). This paper not only provides a new potential low-carbon material for steel bridge deck paving projects, but also establishes a theoretical foundation for the optimization design and promotion polyurethane mixture.

Influence of Petroleum-Based and Bio-Derived Recycling Agents on High-RAP Asphalt Mixtures Performance

Reclaimed asphalt pavement (RAP) has been utilized as a potential partial substitute for virgin asphalt binder in asphalt mixtures. However, a primary concern with increasing RAP content in asphalt mixtures is the cracking potential, attributed to the aged RAP asphalt binder (RAP-binder). To address this, the use of petroleum-based and bio-derived recycling agents (RAs) in enhancing the cracking resistance of high-RAP asphalt mixtures has been explored. The objective of this study is to ascertain the effectiveness of six RAs in mitigating cracking in high-RAP asphalt mixtures. The RAs considered include petroleum-crude-oil-derived aromatic oil, soy oil, and four types of tall-oil-derived phytosterol (industrial by-product, intermediate, purified, and fatty acid-based). The RAs’ dosages were optimized, based on RAP-binder and unmodified asphalt binder properties, to produce target PG 70-22 asphalt binder when incorporated in asphalt mixtures containing 30% RAP. To assess the engineering performance of these 30%-RAP asphalt mixtures for each RA, a conventional asphalt mixture incorporating styrene-butadiene-styrene (SBS)-modified PG 70-22 asphalt binder without RAP or RAs was benchmarked for comparison. Mechanical tests performed included Hamburg wheel-track testing (HWTT), intermediate-temperature fracture tests (semi-circular bend, Illinois flexibility index, and IDEAL cracking tolerance), and thermal stress-restrained specimen tensile strength test to evaluate permanent deformation, intermediate-temperature cracking resistance, and low-temperature cracking resistance, respectively. Results showed that petroleum-crude-oil-derived aromatic oil and tall-oil-derived fatty-acid-based oil RAs were able to rejuvenate RAP-binder as measured by the cracking tests performed. Further, the use of these RAs did not adversely impact the asphalt mixtures’ permanent deformation performance.

Low-Temperature Airflow-Drying Cracking Coupling with Flexible Mechanical Deshelling for Camellia oleifera Fruit: Process and Mechanism

Addressing the problems of high seed-breaking ratio and difficult seed-shell separation in the current mechanical deshelling of Camellia Oleifera fruit (COF), this work innovatively proposed a strategy of low-temperature airflow-drying cracking coupling with flexible mechanical deshelling. The cracking ratio of COF reached 100% after airflow-drying at 20–50 °C for 4–10 h. Moreover, the tissue structure of the Camellia shell remained unchanged after airflow drying. The mechanical shelling ratio of cracked fruits (cracking gap 6 mm) reached 98.37%, and the shells present as integrated lamelliform for facilitating later sorting. The results of low-field nuclear magnetic resonance (LF-NMR) and shrinkage equation showed that the free water of outer layers in the Camellia shell evaporated first, then the free water of inner layers transferred to outer layers to further evaporate, creating a moisture gradient and moisture stress to cause the shrinkage of shell and cracking of COF.

Evolution of Rheological and Microscopic Properties of Asphalt Binders under Fuel Corrosion

Vehicle fuel leaks can adversely affect the performance of asphalt pavements. To study the mechanisms of fuel corrosion damage in asphalt, four asphalt binders were selected in this study, and the evolution of their rheological and microscopic properties was investigated. Fuel corrosion caused continuous mass loss in asphalt binders. Base asphalt lost more than 50% of its mass after 24 h of fuel corrosion, while modified asphalts had better resistance. According to dynamic shear rheometer tests and multiple stress creep recovery tests, modifiers improved the high-temperature rheological properties of these asphalt binders. As the degree of fuel corrosion deepened, the indexes characterizing the high-temperature performance deteriorated. Rubber-modified asphalt showed the best resistance to high-temperature deformation, while the performance of LDPE-modified asphalt was more stable. In contrast, fuel corrosion improved the resistance of asphalt binders to low-temperature cracking to some extent: the creep strength (S) decreased as the creep rate (m) increased, and the resistance of SBS-modified asphalt to low-temperature cracking was optimal, with a 36% decrease in S-value after 24 h of fuel corrosion. Fourier transform infrared spectroscopy tests showed that diesel corrosion was a process of this physical dissolution, with no change in the chemical functional groups. Meanwhile, by using fluorescence images and analyzing the four-component test results, we found that fuel corrosion disrupted the stabilized structure formed by the modifiers, and the heavy components in the asphalt binders were converted into light components. This study reveals the evolution of the rheological and microscopic properties of asphalt under fuel corrosion, which can provide a reference for the optimization of fuel corrosion resistance in asphalt pavement.

Enhancing the physical properties of styrene-butadiene-styrene (SBS)-modified asphalt through polyetheramine-functionalized graphene oxide (PEA-GO) composites

To enhance the dispersion of graphene oxide (GO) in Styrene-butadiene-styrene (SBS) modified asphalt (SA) and the comprehensive physical properties of GO/SBS-modified asphalt (GSA), PEA-GO composites were prepared by grafting polyetheramine (PEA) onto GO for the preparation of PEA-GO/SBS-modified asphalt (PGSA). In this study, the chemical structure of PEA-GO was examined using fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The conventional properties of GSA and PGSA were analyzed. The effects of GO and PEA-GO on the high and low-temperature prevalent properties of SA were investigated by dynamic shear rheology (DSR) test and bending beam rheology (BBR) test. The adhesion properties of GSA and PGSA were investigated by surface free energy theory (SFE). The surface micro-morphology of GSA and PGSA and the dispersion state of GO in SA were analyzed using atomic force microscopy (AFM) and fluorescence microscopy (FM). The results showed that the characteristic absorption peaks of N-H, CH2-CH2, and C-N appeared in the FTIR diagram of PEA-GO. A new peak appeared in the XPS diagram: C-N. The high-temperature performance, low-temperature crack resistance, and adhesion of PGSA were superior to those of GSA. The size of the "bee structure" in PGSA is larger than in GSA, and PEA-GO demonstrates uniform dispersion in SA. This study serves as a reference for fine-tuning graphene oxide (GO) at the microscopic level to enhance the physical properties of GSA.

Rheological performance evaluation of activated carbon powder modified asphalt based on TOPSIS method

In this study activated carbon powder (ACP) was incorporated into asphalt to substitute a portion of the conventional filler (mineral powder, MP). The dynamic modulus at elevated temperatures, temperature-dependent viscosity sensitivity, low-temperature creep, and the interaction between asphalt and ACP were examined through dynamic shear rheometer testing, viscosity testing, and bending beam rheometer testing. Moreover, statistical methodologies such as the entropy weight method (EWM) and the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) were employed to optimize the proportion of ACP by evaluating the comprehensive rheological behavior of asphalt mastic (including high temperature performance, low temperature performance, flowability, and asphalt-ACP interaction). The findings demonstrate that ACP can enhance the resistance of asphalt mastic to high-temperature deformation to a certain degree. The ratio of creep rate to stiffness (m/S) decreases with the addition of ACP, indicating that ACP may exacerbate the occurrence of low-temperature thermal cracking in asphalt mastic. The interaction ability of asphalt mastic is significantly enhanced when a portion of the filler is replaced with ACP. The loss factor shows significant impact on the comprehensive evaluation. According to TOPSIS analysis, asphalt mastic with a blending proportion of 40% ACP and 60% MP performs better in terms of comprehensive rheological properties.

Research on high and low temperature rheological properties of TPU/SBR composite modified asphalt

In road engineering, SBS modifier has been widely applied in China to enhance the quality of asphalt pavement. However, without considering the physical and chemical properties of SBS modifier and the asphalt substrate, alternative polymerization methods for asphalt modification that offer better performance and economic benefits have not been explored. In this study, an approach was taken to compound modify the base asphalt by incorporating Thermoplastic polyurethane (TPU) and Styrene Butadiene Rubber (SBR). The high and low temperature rheological properties of the modified asphalt were examined using tests such as Rotational Viscosity (RV) test, Dynamic Shear Rheological test (DSR), Multiple Stress Creep Rheological test (MSCR), and Bending Beam Rheological test (BBR). The modification mechanism of the mixed modified asphalt, combining SBR and TPU, was investigated through fluorescence microscope testing. The RV test revealed that the inclusion of TPU and SBR enhanced the viscosity of the asphalt to a certain extent, affording it favorable workability during construction and improved resistance against high temperature deformation. DSR and MSCR tests demonstrated that the incorporation of TPU significantly bolstered the external load resistance, deformation recovery, rutting resistance, and overall stability of the SBR modified asphalt under high temperature conditions; The BBR test proves that the composite modified asphalt has excellent low temperature crack resistance. The FM tests have shown that TPU are effective in reducing the segregation that may occur in SBR-modified asphalt, thus improving the performance of the composite modified asphalt.

Performance evaluation of aged asphalt rejuvenated with waste cooking oil on rheological and chemical characteristics

Abstract This study investigates the influence of varying aging processes on the rheological behavior and microscopic features of bio-based recycled asphalt, focusing on the utilization of waste cooking oil (WCO) as a rejuvenator. The research evaluates the rheological and fatigue characteristics of the modified binder, alongside a detailed microscopic analysis to determine the molecular composition changes in both aged and recycled asphalt. The incorporation of WCO was found to compromise rutting performance slightly, yet significantly enhance fatigue resistance and reduce susceptibility to low-temperature cracking. With the progression of aging, an increased dosage of WCO effectively mitigated the negative impacts, bringing the molecular composition and functional groups of the aged asphalt closer to that of the original material. Despite these improvements, a full restoration to the asphalt’s original properties remained elusive. These findings underscore the potential of waste bio-oil as a sustainable resource for enhancing the durability and environmental friendliness of asphalt pavements.

Quantifying the agglomeration effect of reclaimed asphalt pavement on performance of recycled hot mix asphalt

The utilization of reclaimed asphalt pavement (RAP) is becoming widespread in asphalt pavement industry. However, the agglomeration of RAP might exist during asphalt mixture production, which can affect the performance of asphalt mixtures. This study aimed to develop an innovative RAP agglomeration quantification method and investigate the agglomeration effect on performance of recycled hot mix asphalt (RHMA). The inherent agglomeration rate (IAR) and relative agglomeration rate (RAR) were defined and quantified by using the gradation curves. The RAP agglomeration was further determined under different mixing conditions including aggregate size, mixing time, temperature, etc. The influence of RAP agglomeration on hot mix asphalt mixture (HMA) was characterized through wheel rutting, low-temperature cracking, and moisture resistance testing. Results showed that RAP agglomeration do exist during asphalt mixture production, especially for high RAP content. The gradation curves from screening test proved to be an effective approach for RAP agglomeration quantification. The agglomeration rates of No.1, No.2, and No.3 RAP aggregates could be reduced by 5.7, 6.5 and 39.8 % under appropriate mixing conditions. But the fine RAP aggregates were easily re-agglomerated to form the coarse RAP aggregates. The ratio of 150 % between virgin coarse aggregate and RAP aggregate could avoid re-agglomeration issue for No.2 and No.3 RAP aggregates. Based on the rutting, low-temperature cracking, and moisture resistance tests, the impact of agglomeration phenomenon on the performance of plant RHMA with containing 100 % RAP was more than that with containing 50 % RAP.

Effects of Thermo-Reversible Aging on the Cracking Resistance of Asphalt Mixtures in the Semi-Circular Bend Test

The semi-circular bend (SCB) test has been widely used to evaluate the cracking resistance of asphalt mixtures. However, uncertainty has arisen with respect to the accuracy of the test method in cold regions where thermo-reversible aging of the asphalt binder plays a significant role in determining the cracking resistance of asphalt pavement. This study aimed to optimize the current SCB protocol by including an evaluation of thermo-reversible aging phenomena. Asphalt mixtures were collected from different regions in North America. Two groups of SCB samples were prepared, with one tested at 0°C after 2 h of conditioning at the test temperature, and the other tested at the same temperature after 72 h of conditioning at −20°C. The SCB tests were conducted at 50 mm/min and the force was recorded versus both the vertical load line displacement and horizontal crack mouth opening displacement (CMOD). To quantify the effects of thermo-reversible aging on cracking resistance, indicators including the flexibility index (FI), fracture energy (FE), cracking resistance index (CRI), balanced cracking index (BCI), and cracking initiation index (CII) were calculated. The results show that the FI and BCI are greatly affected by cold conditioning, decreasing by 34.6 % and 22.3 %, respectively. The post-peak slope of the force–CMOD curve deteriorates to varying degrees, which provides guidance for optimizing the current SCB protocol to better rank the low-temperature cracking resistance of asphalt mixtures. In contrast, the CII is affected to only a minor degree by thermo-reversible aging and is also a preferred indicator from a repeatability perspective. Important variations in stress relaxation ability (e.g., m-value, phase angle), and how these respond to cold conditioning, are missed in rapid SCB mixture tests and therefore best determined on recovered asphalt binder.

Advanced testing and characterization of low-temperature cracking in bitumen and mastic

Low-temperature cracking is one of the most common failures in asphalt pavements, especially in cold regions. Accordingly, considerable amount of research has been performed in order to understand the low-temperature cracking mechanisms and to propose test methods for characterizing and determining cracking performance of bitumen and asphalt mixtures under freezing conditions. The existing test methods, however, require expensive equipment and skilled technicians; they are thus not well suited for routine tests. As a contribution to mitigate this situation, this study intends to investigate experimentally and characterize numerically the low-temperature cracking behavior of bitumen and mastic materials using a refined thermal cracking test method. The proposed method, the annular restrained cold temperature induced cracking (ARCTIC) test, allows to determine the low-temperature cracking properties of the mastic and bitumen with a relatively simple setup. In this paper, finite element (FE) modeling is used for evaluating the effect of test parameters on the temperature, stress and strain gradients induced in the specimen during the test. The ARCTIC test is employed to measure cracking temperatures of two bitumen and two mastic materials. The measurements repeatability is examined and the effect of bitumen type on the thermal cracking potential of bitumen and mastic is evaluated. FE modeling is employed to examine the effect of thermomechanical parameters on thermal cracking performance of the materials and to back-calculate fracture stress and strain from measurements. The results highlight the potential of the proposed test and analysis method for evaluation of low-temperature cracking in bitumen and asphalt mastic.

The Influence of the Application Layer of Pouring Semi-Flexible Pavement Material on Low-Temperature Stress

Pouring semi-flexible pavement material (PSFM) is widely used as a wearing layer material or below pavement due to its excellent resistance to deformation at high temperatures and under heavy loads. However, in cold regions, the material exhibits severe cracking issues. The primary objective of this study is to enhance the resistance of pouring semi-flexible pavements (SFPs) to low-temperature cracking in cold regions by strategically designing pavement structures that incorporate PSFM. To achieve this goal, we conducted indoor tests to determine the relaxation modulus and temperature shrinkage coefficient of PSFM and simulated a pavement structure using COMSOL finite element simulation. The impacts of different application layers and layer thicknesses on low-temperature stresses were investigated based on these findings. The research findings indicate that when PSFM is used as the wearing layer material, the low-temperature stress is 4.7% lower than that of typical materials used in the pavement-wearing layer. When used as the binder layer material, the low-temperature stress on the wearing layer material increases by 3.5%. As the thickness of the wearing layer increases, the low-temperature stress within the pavement structure decreases, but the low-temperature stress on the pavement surface increases. Therefore, it is recommended to use PSFM as the binder layer material and appropriately increase the thickness of the wearing layer to enhance the pavement’s resistance to low-temperature cracking.

Thermoreversible aging in asphalt binders

It is an undisputed fact that aging increases the risk of low-temperature cracking in asphalt pavement. Previous studies on aging have focused on oxidative aging, but few studies on thermoreversible aging have been reported. The existing literature has shown that thermoreversible aging has the same effect as oxidative aging on cracking of asphalt pavement in cold region, so it is obvious that the study of thermoreversible aging is of great practical significance to improve cracking of asphalt pavement. This paper introduces the current status of thermoreversible aging research from the concept, mechanisms, characterisation methods and effects, presents the problems of existing research and indicates the direction of further research, which is important for accurately characterising the mechanical properties of asphalt binders, controlling the waste addition ratio and improving the durability of asphalt pavement.

Rejuvenating oxidized paving asphalts – When softeners meet asphaltene dispersants

The search and development of various asphalt rejuvenators have been following a trial-and-error methodology in essence; the imperative need of improved efficiency and versatility yearns for a general principle/framework of formulating rejuvenators. In this study, we propose one such formulation concept that rejuvenators can be designed by combining asphaltene dispersants (interacting with and dispersing asphaltenes) with softeners (diluting asphaltenes). This concept was preliminarily validated in an experimental program involving three rejuvenation schemes, namely using an aromatic softener alone (as the reference) and using it together with an ionic liquid or a phenolic compound (both acting as dispersants). Immediate and long-term rejuvenating effectiveness was evaluated based on viscoelastic properties, fatigue resistance, and moisture susceptibility. The results indicated that at respective optimum dosages, the three schemes all yielded satisfactory immediate performance of rejuvenation. After long-term aging, the rejuvenated asphalts demonstrated more desired viscoelastic characteristics in resisting high-temperature deformation and low-temperature cracking, and were more fatigue resistant, as compared to the virgin binder. Rejuvenation in all cases also recovered the moisture resistance nearly to the virgin level. Infrared spectrum analysis indicated that the performance restoration was accomplished by the agents blending physically with the aged binder, which decreased the concentrations of oxidation functional groups (carbonyl and sulfoxide). The incorporation of dispersants improved the aging resistance (in terms of high temperature viscoelasticity), and substantially reduced the need of aromatic softener while providing similar or better performance compared to using the softener alone, which would lead to pronounced environmental and economic benefits. The much higher dosage efficiency was ascribed to the capability of the dispersants in peptizing and dissociating the asphaltenes, as investigated by molecular dynamics simulations. The different dispersing behaviors of the additives were examined with reference to their chemical compositions and molecular structures.

Pure mode I fracture specification of molybdenum disulfide nanoparticles (MDS)-reinforced hot mix asphalt (HMA) under long-term conditions

Low and intermediate temperature cracking are two key factors for fracture and failure of hot mix asphalt (HMA), which impose huge costs on transportation departments and related agencies around the world. These two kinds of cracking may apear in the short- or long-term owing to states such as freezeing-thawing damage (FTD) and the aging mechanism. On the other hand, due to its unique features, nanomaterials are a suitable option for improving the mechanical features of bituminous mixes, which can affect the short-term performance and long-term performance. In this study, low and intermediate temperature fracture specification of Nano-molybdenum disulfide (MDS)-reinforced hot mix asphalt (HMA) under long-term conditions was evaluated. For this goal, two semi-circular bend (SCB) geometries comprising 90 degree and angled cracks, which were called symmetric SCB and classical-reinforced SCB-2, were made. Then, two various conditions, i.e. three freeze–thaw cycles and six days of aging operation were performed on various mixes in order to simulate the long-term performance of the bituminous mixes. Finally, the HMA samples with and without MDS were subjected to the three-point SCB test at the final temperatures of −15 °C and + 15 °C. The findings demonstrated that mixes comprising 0.3 % and 0.6 % MDS had more increased fracture energy (FE), fracture toughness (KIC), and stiffness under pure tension at low and medium temperatures (short-term and long-term fracture specification). In fact, MDS caused an increase in the fracture indices by increasing the maximum force (Pmax) and displacement at the time of fracture. At ± 15 °C and for the geometry comprising the 90 degree and 35 degree cracks, the HMA and Nano MDS-reinforced HMA mixes had more suitable flexibility under 3 FTC compared to 0 FTC; while, the flexibility of the HMA and Nano MDS-reinforced HMA mixes decreased under aging mechanism. In discussing the long-term performance of HMA mixture (with and without modifiers), the findings showed that applying three FTD's cycles to the mixes caused a decrease in KIC, FE, and Pmax. Also, reducing the stiffness of various mixes under 3 FTC, and increasing the flexibility of the mixes were other findings of this study. In addition, the simultaneous use of both SCB geometries comprising 90 degree and 35 degree cracks was proposed to study the fracture specification of bituminous mixes owing to the more inferior average FE and KIC. Finally, the application of 3FTC on bituminous mixes can more suitable simulate the long-term performance of asphalt pavement (compared to aging mechanism).

Microscale interface mechanism of the improved high and low-temperature performance of modified bamboo fibres-reinforced asphalt mixture

ABSTRACT Using plant fibres to reinforce asphalt mixture and improve its road performance has attracted growing interest. To improve the interfacial adhesion between bamboo fibres (BFs) and asphalt matrix, BFs were treated with acrylate epoxidized soybean oil (AESO) and 4,4'-diphenyl methane diisocyanate (MDI). The high-temperature stability and low-temperature cracking resistance of the modified BFs-reinforced asphalt mixture were evaluated by the rutting and bending experiments, respectively. The dynamic stability at 60°C and the flexural strength at −10°C of the mixture with modified BFs were improved by 21.67% and 22.84%, respectively. Then, molecular dynamic simulations were implemented to investigate the effect of fiber modification on the interface properties. Simulation results showed that as the grafting density increased from 0 to 2.21 × 10–7 mol/m2, the binding energy increased by 277.2% and 159.3% at 65°C and −15°C, respectively, and the diffusion coefficient decreased by 50.8% and 27.7% at 65°C and −15°C, respectively. As the grafting density further increased to 4.43 × 10−7 mol/m2, the interface performance deteriorated because the dense grafted molecular chains inhibited the diffusion of asphalt to BF surfaces. This work provides an understanding of the interfacial mechanism for optimising the BF-reinforced asphalt mixtures.

Preparation and Performance of Bitumen Modified by Melt-Blown Fabric of Waste Mask Based on Grey Relational and Radar Chart Analysis.

To effectively utilize waste mask materials in road engineering and minimize resource waste, the melt-blown fabric (MBF) of waste masks was utilized to modify the virgin bitumen. The preparation process of MBF-modified bitumen was investigated, and the physical and rheological properties of bitumen were measured. Subsequently, the blending mechanism during preparation and the dispersion morphology of the modifier were explored. Finally, the pavement performance of the mixture was investigated, and a radar chart analysis was performed to quantitatively assess the effects of MBF modification. Results suggested that the recommended preparation process of shear time, shear rate, and shear temperature was 170 °C, 4000 r/min, and 15 min, respectively. MBF enhanced the high-temperature stability of the binder and weakened the temperature susceptibility. The modification was primarily a physical process. No network structure and agglomeration formed in the bitumen after modification. The addition of MBF significantly improved the resistance of the asphalt mixture to a high-temperature deformation and water damage but harmed its low-temperature crack resistance. The comprehensive assessment results of 0% (f1), 1% (f2), 3% (f3), and 5% (f4) MBF to improve the properties of the mixture were in the following order: f3>f4>f2>f1, where the impact of 3% MBF was the most significant, followed by 5% and 1% MBF.

Study on asphalt damage characteristics in cold area with large temperature gradient

The primary cause of the asphalt pavement disease in this region is the large temperature differential and high ultraviolet (UV) radiation that characterize this frigid environment. This study assessed the ductility, penetration, softening point, and rheological properties of several asphalts under various freeze-thaw cycles and UV aging conditions. Additionally, the damage characteristics of asphalt in cold and large temperature gradient areas were examined. The findings indicate that the freeze-thaw cycle significantly affects the asphalt’s low-temperature crack resistance but has no discernible effect on the material’s traditional performance or high-temperature rutting resistance. Asphalt’s resistance to low temperature cracking is ranked according to the impacts of UV radiation and the freeze-thaw cycle: 80/100 pen grade asphalt, 100/120 pen grade asphalt, SBS modified asphalt, and SBR modified asphalt. The impact of UV radiation and the freeze-thaw cycle on the high temperature performance of asphalt is categorized into four categories: SBR modified asphalt, SBS modified asphalt, 80/100 pen grade asphalt, and 100/120 pen grade asphalt.