Fiber-reinforced Asphalt Mixtures Research Articles

Evaluation of Impact of Mixing Method on Laboratory- and Plant-Produced Fiber-Reinforced Asphalt Mixture

Evaluation of Impact of Mixing Method on Laboratory- and Plant-Produced Fiber-Reinforced Asphalt Mixture

Fatigue Performance Evaluation of Fiber-Reinforced Asphalt Mixtures with Four-Point Bending Beam and Uniaxial Fatigue Tests

This study aimed to evaluate the fatigue cracking potential of aramid fiber–reinforced asphalt mixtures. Three fiber-reinforced asphalt mixtures (FRAMs) were prepared employing a singular aggregate type (diabase stone), one binder type (PG76-22), and two distinct combinations of aramid fibers at varying dosages. Two types of fiber were used at different dosages by weight of mix: polyolefin/aramid (PFA) fibers at a dosage 0.05% and sasobit-coated aramid (SCA) fibers at dosages of 0.01% and 0.02%. Additionally, an unreinforced (control) mix was also produced for comparison purposes. Each of the mixtures was produced at a batch plant, adhering to the fiber manufacturer’s recommended mixing methods, while maintaining a constant binder content of 5.5% based on the total mix weight. Four-point beam (4PB) fatigue, uniaxial fatigue (UF), and Texas overlay tests (OT) were performed to characterize the fatigue and reflective cracking behavior of FRAM. The 4PB test results suggest that FRAM improved the fatigue life at lower strain levels (400 µε and 600 µε); however, at higher microstrain (800 µε) level, FRAM exhibited lower fatigue life than the control mix. Damage characteristic curves obtained from the UF tests showed better fatigue tolerance for reinforced mixtures, regardless of microstrain level. For cycles to failure under tensile loading, UF and OT test results indicated lower fatigue life of reinforced mixtures compared with the control mix. Therefore, under flexural loading the fiber-reinforced asphalt mixtures tend to improve the fatigue life. However, for direct tension load, reinforced mixtures tend to deteriorate the fatigue life when comparing cycles to failure at constant strain amplitude.

Composite Granular Fiber-Reinforced Asphalt Mixture: Preparation, Performance, and Mechanism

Composite Granular Fiber-Reinforced Asphalt Mixture: Preparation, Performance, and Mechanism

Laboratory performance characterization of polyolefin/ aramid fibers and synthetic aramid fibers reinforced asphalt mixtures

This study was conducted to assess the impact of combined polyolefin/aramid fibers (PFA) and pure synthetic aramid fibers (AF) reinforcement on mix design properties and laboratory performance. The study also investigated the shift in laboratory performance (rutting to cracking and vice versa) with the addition of both type of fibers. One aggregate (diabase stone), one binder type (PG58–28), and two types of aramid fibers (combined polyolefin/ aramid fibers and synthetic aramid fibers), added at 0.05% dosage by mix weight, were used to produce two fiber-reinforced asphalt mixtures (FRAM). Additionally, a control mix was also produced without any reinforcement. Mix design for control and FRAM was performed and Optimum Binder Content (OBC) was determined. The laboratory rutting and cracking performance of the mixtures was assessed using Asphalt Pavement Analyzer (APA), Flow Number (FN) and Indirect Tension Asphalt Cracking Test (IDEAL-CT). Durability and stiffness of these mixtures were also determined by performing Cantabro loss and Dynamic Modulus (DCM) tests. According to the mix design results, PFA reinforced mix showed an offset bulk and theoretical maximum specific gravity. However, both control and FRAM mixtures showed the same OBC (5.7%). Both type of fibers improved the durability of mix. With addition of PFA and AF fibers into the asphalt mix, the performance trend shifted from rut resistant mix to crack resistant mix, respectively. Furthermore, addition of PFA fibers into the asphalt mix increased the toughness and AF fibers make the asphalt mix ductile.

Micromechanical behavior of single fiber-asphalt mastic interface: Experimental studies by self-designed innovative pullout test

Micromechanical behavior of the interface between fiber and asphalt is a crucial factor in the performance of fiber reinforced asphalt concrete, and a thorough understanding of this behavior is essential for the design and optimization of these materials. To evaluate the micromechanical behavior of the interface, an innovative single fiber pullout test platform was designed, and the experimental parameter conditions were systematically studied. Three types of fibers including basalt fiber (BF), glass fiber (GF) and polyester fiber (PF) were adopted, and the pullout test was performed at 60 ℃, 25 ℃ and −10 ℃, respectively, where the micromechanical behavior at the interface under different experimental conditions was obtained. The results showed that the recommended loading rate of the fiber pullout test is 1–3 mm/min, and the measurement of variability is satisfactory. The single fiber pullout behavior was observed and the load-displacement curve was recorded real-time. Three failure modes (fiber pullout, fiber fracture and matrix failure) at the interface between the single fiber and asphalt mastic were observed. Furthermore, a bond-slip model which can accurately characterize the bonding-debonding behavior of the interface between the single fiber and asphalt mastic was established. It was found from the study that micromechanical behavior of the interface between the single fiber and asphalt mastic is influenced by the type of fiber and temperature, the peak load and displacement are significantly different. These findings presented in this study can play a significant role in revealing the reinforcement mechanism of fiber and providing a guidance for the efficient application and development of fiber reinforced asphalt mixture.

Evaluation of Low- and Intermediate-Temperature Cracking Performance of Fiber-Reinforced Asphalt Mixtures

This study was conducted to assess the impact of aramid fiber reinforcement on the fatigue and thermal cracking performance of asphalt mixtures at intermediate and low temperatures, respectively. The study also involved evaluating the experimental consistency and ranking fiber-reinforced asphalt mixtures (FRAMs) based on their performance. One aggregate (diabase stone), one binder type (PG 76-22), and two combinations of aramid fibers, added at different dosages, were used to produce three FRAMs. These fibers included polyolefin/aramid (PFA) fibers at 0.05% dosage by mix weight and Sasobit-coated aramid (SCA) fibers at 0.01% and 0.02% dosages. An unreinforced (control) mix was also produced without any reinforcement. All mixtures were produced at a batch plant by keeping their binder content constant (at 5.5%). The manufacturer recommended dry and wet mixing times were used for better fiber distribution and represent actual mixing conditions. The laboratory performance of plant-produced FRAMs was assessed to characterize the low- and intermediate-temperature cracking performance. The indirect tension asphalt cracking test, semi-circular bend test, three-point bending beam tests, and uniaxial fatigue tests were performed at intermediate temperature; the disk shape compact tension test and thermal stress restrained specimen test tests were performed at low temperature. Fibers were successful at improving the fatigue cracking of asphalt mixtures based on intermediate-temperature testing results. In addition, fiber reinforcement, regardless of dosage and combination, showed improvements in low-temperature (thermal) cracking performance. Furthermore, based on ranking analysis for selected performance indicators from each experiment, the SCA 0.02% reinforced mix on average showed the highest cracking resistance.

Research on properties of basalt fiber-reinforced asphalt mastic

A basalt fiber-reinforced asphalt mixture can improve the engineering properties of asphalt pavement and prolong the service life of the road. However, few studies have systematically examined the composition of asphalt mixtures or the optimal ratio of fiber asphalt mastic suitable for different structural types. The effects of fiber content, filler–asphalt ratio, and asphalt viscosity on the properties of fiber asphalt mastic were investigated by orthogonal experiments to explore the reinforcement effect of basalt fiber on asphalt mastic. The optimal ratio of fiber asphalt mastic suitable for gap-graded and dense-graded asphalt mixtures was obtained by the fuzzy comprehensive evaluation (FCE) method. Meanwhile, the reinforcement effects of bundled basalt fiber (BBF), flocculated basalt fiber (FBF), polyester fiber (PF), and lignin fiber (LF) on asphalt mastic were compared and analyzed based on the optimal ratio of FBF asphalt mastic. The results showed that the optimal fiber asphalt mastic ratio suitable for gap-graded and dense-graded asphalt mixtures were that fiber content, filler–asphalt ratio, and asphalt viscosity were 3%, 1.8, and 1.1 Pa·s and 2%, 1.0, and 0.7 Pa·s, respectively. Analyzing the properties of different types of fiber asphalt mastic revealed that FBF could effectively enhance the high-temperature rheological properties and low-temperature tensile properties of asphalt mastic compared with other fibers. FBF asphalt mastic improved the asphalt rutting factor by more than four times. The tensile fracture energy of fiber asphalt mastic was more than three times that of the corresponding asphalt. The reinforcement effect of BBF was poor; it was recommended to be broken up before use.

Effect of aging on the low-temperature performance of fiber-reinforced asphalt mixtures

To study the effect of aging on the low-temperature crack resistance of fiber asphalt mixes, three kinds of fibers (lignin fiber, polyester fiber, and basalt fiber) were dry blended into AC-13 asphalt mixes to prepare unaged, asphalt aged (that is, the original asphalt material is subjected to aging treatment), short-term aged, and long-term aged fiber reinforced asphalt mixes. Semicircular bending (SCB) tests and scanning electron microscopy tests were used to analyze and study the effects of aging time and fiber type on the low-temperature properties of asphalt mixtures at an ambient temperature of −5 °C. The SCB test results indicated that: with the deepening of aging, the fracture toughness and fracture energy of the fiber asphalt mixture specimens will tend to decrease, and the aging of the original asphalt has a greater impact on the specimens without fiber; there was great variability in the effect of lignin fibers on the crack resistance of the mix, but it could be a good promoter in unaged asphalt mixes; polyester fiber is the material of choice for improving low-temperature crack resistance in long-term aging pavements; the incorporation of basalt fiber greatly enhances the crack resistance of asphalt mixes and is an excellent material for improving aging asphalt mixes. It is clearly seen by the scanning electron microscope test that with the deepening of aging, the adhesion of asphalt and aggregate gradually deteriorates, and even more so, there is the phenomenon of fine aggregate flaking, and the fiber cannot play an excellent role in reinforcement and crack resistance.

Performance evaluation of asphalt mixture reinforced by lignin and ceramic fiber

A single-adding fiber technology only plays a role in improving one performance of asphalt mixture such as high temperature or low temperature or water damage performance. Although double-adding fiber-reinforced asphalt mixtures are expected to improve overall road performance, existing research still only focuses on the analysis of a single performance. In this study, two representative fibers including lignin fiber (LF) and ceramic fiber (CF) were selected including to investigate the role of double-adding fibers in asphalt mixtures. The effect of different fiber proportions on the overall road performance of stone matrix asphalt (SMA-13) mixtures was analyzed via wheel tracking tests, low temperature bending test, moisture susceptibility test and fatigue test, etc. The results revealed that the combined addition of LF and CF exhibited superior improvements in mechanical strength, anti-rutting performance, moisture susceptibility, and fatigue life as compared to that of using either fiber alone. Specifically, compared to that of SMA mixtures using LF, the SMA mixtures using both two fibers improved in 11% dynamic stability, 8.6 % low-temperature bending stress, 2.1 % moisture susceptibility and 20 % fatigue life, respectively. And compared to that of SMA mixtures using CF, the mixtures using both two fibers increased in 11 % low-temperature bending strain and 8 % fatigue life, while improving slightly in dynamic stability, low-temperature bending stress, and moisture susceptibility respectively. Based on the results of efficiency coefficient method, the recommended ratio of LF to CF in the asphalt mixture is 1:2, providing a more balanced and comprehensive enhancement of road performances. This study provides a theoretical reference for the engineering application of improving the road performance of asphalt mixture through composite fiber blending, which can effectively enhance the service life of asphalt pavement.

Modification and Enhancing Contribution of Fiber to Asphalt Binders and Their Corresponding Mixtures: A Study of Viscoelastic Properties.

The performance of asphalt binders and asphalt mixtures can be enhanced by the inclusion of fiber. The viscoelastic characteristics of fiber-reinforced asphalt binders and their corresponding mixtures were characterized in this study. To generate fiber-reinforced asphalt samples for dynamic shear rheometer (DSR) tests, polypropylene fibers (PPFs), polyester fibers (PFs), and lignin fibers (LFs) were added into modified asphalt with a ratio of 5wt%. Indirect tensile resilience tests were conducted on the fiber-reinforced asphalt mixture with Marshall samples, which was prepared with a 6.4% of bitumen/aggregate ratio. The addition of fiber can increase the anti-rutting performance of asphalt binders, and also reduce the anti-fatigue performance of asphalt binders to varying degrees. Viscoelastic properties of the fiber-reinforced asphalt binders are highly dependent on the shape of the used fiber. The resistance of the fiber-reinforced asphalt binders to rutting at high temperatures increases with the roughness degree of the fiber's surface morphology. PPF-reinforced asphalt binders surpass the others in terms of anti-rutting capabilities. The high-temperature deformation resistance of the PPF-reinforced asphalt mixture is stronger, whereas the low-temperature crack resistance of the PF-reinforced asphalt mixture is stronger, which can be observed from the master curve of indirect tensile resilient modulus.

Assessment of the impact of binder grade on the laboratory performance of fiber reinforced asphalt mixtures

This study aims to evaluate the impact of different fiber types and binder modifications on the volumetric properties and performance (rutting and cracking) of fiber-reinforced asphalt mixtures (FRAM). Four types of fibers (carbon, fiberglass, basalt, and polyolefin/aramid (PFA) mix) and two binder performance grades (PG 58–28 unmodified and PG 76–22 polymer modified) were used to produce a total of ten asphalt mixtures (two control and eight FRAM). All fibers were introduced at the manufacturer-recommended dosages (i.e., carbon, fiberglass, basalt: at 0.16%, and PFA: at 0.05%) by mix weight. The mix design and volumetrics properties were examined to assess the impact of FRAM on volumetric properties of modified and unmodified binders. Mix characteristics, durability, rutting, and cracking performances were also evaluated by performing several tests, including dynamic modulus test |E*|, Cantabro loss, Asphalt pavement Analyzer (APA), Flow Number (FN), and Indirect Tensile Asphalt Cracking Test (IDEAL-CT). Mix design results showed that FRAM at 0.16% dosage increased the air voids of the unmodified binder (PG58-28). PFA fibers did not have an impact on air voids or volumetric properties of the asphalt mix regardless of modification. Performance results showed that FRAM were highly durable than control mix, but durability is significant for polymer modified binder (PG76-22). Furthermore, only PFA reinforced mixtures showed better rutting resistance for both modified and unmodified binders. The addition of fibers did not show any impact on cracking performance of modified and unmodified binder prepared asphalt mix. Finally, PFA reinforced mix also indicated higher fracture toughness (Gf) and carbon fibers improved the ductility of asphalt mix.

Fracture studies on basalt fiber reinforced asphalt mixtures with reclaimed asphalt pavement derived aggregates and warm mix additives

The Indian Ministry of Road Transport and Highways’ (MoRT&H) recommended grade II Bituminous Concrete mixture, hitherto referred to as Asphalt Concrete (AC) was investigated during this present research study. Different AC mixtures, with 2 % to 4 % of Sasobit warm mix additive by weight of the asphalt binder, 20 % to 40 % of RAP derived aggregates as replacement to the virgin aggregates and 4 % to 8 % of basalt fibres by weight of the binder as the additive, were investigated during this research study.In addition to the fundamental binder tests, micro structural investigations namely X-Ray Diffraction (XRD) and Fourier-Transform Infrared spectroscopy (FT-IR) were also carried out to understand the crystallographic structure and the functional groups present in the binder, respectively. The efficacy of the WMA and basalt fibre addition in the AC mixtures with RAP derived aggregates was verified through the standard Immersion Type-Hamburg Wheel Track Test (IHWTT) for assessing the rut resistance; through the standard Semi-Circular Bending (SCB) tests for assessing fracture behaviour, and through indirect tensile fatigue test to assess fatigue resistance. It was observed that the AC mixture, with 30 % RAP materials by weight percentage of total aggregates, 6 % chopped basalt fibres by weight percentage of binder and 4 % Sasobit warm mix additive dosage by weight percentage of binder, was found meeting the target AC mixture performance standards.

Evaluation of the Factors Affecting the Performance of Fiber-Reinforced Asphalt Mixtures

This paper summarizes the results of the first comprehensive laboratory study that was conducted to evaluate the effect of using different aramid fiber properties (types, lengths, and dosages) with different combinations on the performance of dense-graded asphalt mixtures reinforced with aramid fibers. Asphalt mixtures with two different aramid fibers (Fiber A and Fiber B) were prepared. For each type of fiber, two lengths and four doses were considered. The semicircular bend (SCB) test, indirect tensile asphalt cracking (IDEAL-CT) test, and the overlay tester (OT) were conducted to evaluate fracture resistance and reflection cracking resistance of prepared mixtures, along with the asphalt concrete cracking device (ACCD) test for evaluating the low-temperature cracking resistance, the Hamburg wheel-tracking (HWT) test for evaluation of rutting susceptibility. Cost analysis was also done to evaluate the feasibility of adding aramid fibers to the asphalt mixtures. Results of the conducted tests indicated that the effects of adding aramid fibers to asphalt mixtures vary depending on the type of aramid fiber and its properties. In general, the addition of the Type A and Type B aramid fibers to the unmodified performance grade (PG) 64-22 mixtures resulted increasing their fatigue lives by 104% and 65%, respectively. Adding Type B fiber [short aramid/polyolefin fiber blend with 12.5 mm (0.75-in.) length] or long Type A fiber (wax-treated aramid fiber with a length of 1.5 in.) to the PG 64-22 mixtures resulted in improving the cracking resistance of reinforced mixtures. In addition, doubling the suppliers’ recommended dosage of each fiber type resulted in significantly lower cracking resistance values. The fibers did not improve the resistance to low-temperature cracking for asphalt mixtures. However, the rutting and moisture susceptibility results for fiber-reinforced mixtures were satisfactory compared with the unreinforced mixtures. Results of cost analysis indicated that the addition of aramid fibers to the mixtures resulted in a significant reduction of construction cost for these mixtures to the values between 27% and 37%. The optimum formulation of both aramid fibers for the purpose of improving cracking resistance of asphalt mixtures was found as 1.5-in. length at the supplier recommended dosage for Type A aramid fiber, and 0.75-in. length and the supplier recommended dosage for Type B aramid fiber.

Fiber-Reinforced Asphalt Mixture Design on Anti-Skid Surfacing for Field Testing High-Speed Vehicles on Pavements.

Fiber can absorb asphalt binder and therefore reinforce and stabilize the asphalt mixture structure and also prevent the asphalt from the leaking, which occurs in the process of mixing and transport. In this study, three kinds of fiber (polyester fiber, polypropylene fiber, and lignin fiber) are used to evaluate the relationship between the fiber types and mechanic performance of SMA-13 fiber asphalt mixture, which is specially designed for field tests of high-speed vehicles on pavements. The micro-surface characteristics of fiber and aggregates were studied by SEM and image analysis. Marshall stability and splitting strength were used to measure the properties of the asphalt mixture. In addition, a field test, including measures for curve-section edge, curve-section center, straight-section edge, and straight-section center, was conducted to evaluate the skid resistance of the high-speed vehicles that test field pavement. The results show that the Marshall stabilities of asphalt mixture with three kinds of fibers have been improved, whereas the stability of asphalt mixture prepared by polypropylene fiber and polyester fiber particularly increased before immersion. Among the three kinds of fiber asphalt mixtures, the polyester fiber asphalt mixture has enhanced water susceptibility. Skid resistance in the field test indicated that high skid resistance and good surface-texture depth were achieved.

Grey Correlation Analysis between Macro Mechanical Damage and Meso Volume Characteristics of SBS Modified Asphalt Mixture under Freeze-Thaw Cycles

The effect of freeze–thaw (F–T) in the seasonal frozen area would lead to damage to asphalt pavement. After water enters asphalt pavement, the water in voids would expand at a lower temperature, which could change the void content and number, affecting the macro mechanical properties of the asphalt mixture. The rapid development of CT scanning and digital image processing (DIP) provides powerful technical support for the research of asphalt mixture meso volume characteristics. In this paper, the mechanical properties of basalt fiber reinforced asphalt mixture subjected to F–T cycles were tested at different temperatures to clarify the decay law of mechanical properties under F–T cycles. Then, the meso images of the asphalt mixture under various F–T cycles could be obtained by using CT tomography. Based on DIP technology, the meso characteristic parameters of CT images for asphalt mixture were extracted, and the development of asphalt mixture freeze–thaw damage was further analyzed. The test results showed that with the F–T cycle, the macro mechanical properties of the asphalt mixture rapidly declined in the early stage of the F–T cycle and gradually tended to be flat. There would be serious damage inside the asphalt mixture in the late stage of the F–T cycle. The damage to the mechanical properties of the asphalt mixture under the F–T cycle can be attributed to the change in the internal mesostructure of the asphalt mixture. Based on the grey relational analysis theory, the formation of the connected void was the main factor affecting the damage in the early stage of the F–T cycle, while the formation of new voids mainly affected the later development of F-T damage.

Low temperature performances of fiber-reinforced asphalt mixtures for surface, binder, and base layers

In the present study, the effects of adding fibers and Reclaimed Asphalt Pavement (RAP) on the low temperature performances of open graded asphalt mixtures for surface layer and dense asphalt mixtures for surface, binder, and base layers were investigated. Two different kinds of fibers were used: a combination of aramid and polyolefins fibers were utilized for preparing fiber reinforced porous asphalt mixtures, while polyacrylonitrile fibers were employed for producing conventional dense asphalt mixtures for surface, binder, and base layers. Reference mixtures were made with virgin materials as a benchmark to study the effects of the fibers' addition. Moreover, asphalt mixtures for surface layers composed of 30% RAP and mixtures for binder layers containing 50% RAP were produced to study the combined effects of fibers and RAP on the low temperature's performance. Thermal Stress Restrained Specimen, Uniaxial Tension Stress, and Semi-Circular Bending tests were used to evaluate the response against thermal distresses. The addition of the fibers showed no significant effects on the low temperature strength, while a remarkable improvement in the failure temperature and crack propagation resistance properties was found. The use of fibers has also shown to be beneficial in combination with mixtures designed with RAP and higher binder content suggesting a dedicated study on mix design for future research.

Influence of fiber-asphalt interface property on crack resistance of asphalt mixture

This paper aims to analyze the interface property between fibers and asphalt, and study its influence on the crack resistance of the asphalt mixture. Four fibers (basalt fiber A (BF-A), basalt fiber B (BF-B), polyester fiber (PEF) and polyacrylonitrile fiber (PAF)) were selected in the study. The interface adhesion parameters were obtained by conducting the novel fiber-asphalt pullout test, and the micromorphology of the fiber-asphalt interface area was also observed. The crack resistance of the mixture was determined using the indirect tensile asphalt cracking test (IDEAL-CT) and the semi-circular bending test (SCB). Basic crack resistance indicators such as CTIndex and flexibility index (FI) were used for analyzing. Meanwhile, digital image correlation (DIC) technology was adopted to quantitatively characterize the crack inhibition mechanism of fibers in the fiber-asphalt mixtures. The results showed that the interface adhesion strength between BF-A and asphalt is the largest at 25 ℃, followed by BF-B, PEF and PAF. The addition of fibers can effectively improve the CTIndex and FI of asphalt mixtures, and it is found that the interface adhesion characteristics between fibers and asphalt have a great influence on the crack propagation process. The crack opening velocity curve obtained from the DIC analysis can quantitatively characterize the crack development law of the asphalt mixture. The coefficient of determination R2 between the interface adhesion strength and the DIC index (stage I velocity change rate and timing point 1 time) exceeded 0.85. The results can provide scientific references for the design and application of fiber reinforced asphalt mixture.

Recent Advances in Basalt Fiber Reinforced Asphalt Mixture for Pavement Applications

This paper conducts a thorough review of the literature on the feasibility and current state-of-the-art incorporation of basalt fiber (BF) into asphalt pavement materials, focusing on fiber characteristics, dosage, incorporation methods, mixture properties, and surface modification techniques. The optimum basalt fiber dosage should be determined based on engineering performance parameters such as asphalt type, fatigue cracking, thermal cracking, rutting, and moisture resistance of asphalt mixtures. Basalt fibers are added to asphalt mixes by dry method or mixed method to achieve better dispersion. Adding BF to asphalt mixtures increased performance characteristics like cracking resistance, rutting resistance, and fatigue resistance. Overall, incorporating BF into asphalt mixtures would lower costs while increasing pavement service life. More research is needed to fully understand the effects of different sizes of BF on pavement performance and the possible environmental and economic repercussions of fiber surface alteration.

Effects of polyacrylonitrile fibres and high content of RAP on mechanical properties of asphalt mixtures in binder and base layers

In this present study, the effects of polyacrylonitrile fibres and high content (50%) of Reclaimed Asphalt Pavement (RAP) on the mechanical properties of asphalt mixtures in binder and base layers were studied. This is the first time that the effect of high RAP content on the mechanical properties of fibre reinforced asphalt mixtures (FRAM) was evaluated, while the low temperature performance was not usually conducted in previous studies. Results indicated that the addition of polyacrylonitrile fibres worsens the moisture susceptibility resistance, but improves the rutting, stiffness properties, fatigue performances, and cumulative fatigue damage of the mixtures with and without RAP. No significant effects on the low temperature cracking resistance were found when fibre was used, while a remarkable improvement in the crack propagation resistance properties was observed. Therefore, the use of polyacrylonitrile fibres improves in general the mechanical responses of the mixture, especially in the stiffness response.

Laboratory Investigation on Pavement Performance of Basalt Fiber-Reinforced Asphalt Mixture Under the Coupling Effect of Freeze-Thaw Cycles and Aging

Due to the significant temperature difference and high solar radiation in high-altitude areas, the asphalt pavement has been in freeze-thaw cycles and radiation service conditions for a long time, resulting in a shorter service life. To extend the service life of asphalt pavement in high-altitude areas, this study uses basalt fiber to toughen the asphalt mixture, and the service characteristics of the asphalt pavement under the coupled effects of freeze-thaw cycles and aging were evaluated. First, the freeze-thaw cycles, aging time, and basalt fiber content were selected as independent variables to conduct the Box–Behnken design (BBD) test design. Consequently, the corresponding response surface model was established. Based on the rutting test, three-point bending test, and indirect tensile test, the optimum content of basalt fiber was obtained. Finally, the fatigue properties of the asphalt mixture by the four-point bending fatigue test were compared under the optimum content. The results showed the consequences of freeze-thaw cycles will reduce the road properties of asphalt and give rise to damage to the asphalt; among them, the indirect tensile strength was decreased by 21.7% at most (the number of freeze-thaw cycles from 10 to 30). Aging will reduce the fatigue life of the asphalt mixture, but its dynamic stability, flexural tensile strength, and slitting strength will be enhanced to a certain extent; among them, the dynamic stability can be improved by up to 28.1% (aging from 4 to 12 h). Basalt fiber can increase the flexural tensile strength, dynamic stability, and spitting strength; the optimum content is 0.35% of asphalt mixtures. Furthermore, the fatigue life of basalt fiber-reinforced asphalt mixture can be significantly improved, which can reduce the influence of freeze-thaw cycles and aging. In addition, the unit price of basalt fiber-reinforced asphalt mixture is only 6.9% higher than that of SBS-modified asphalt mixture, which has significant economic benefits. Under experimental conditions, the effect of aging on the properties of the asphalt mixture is greater than that of the freeze-thaw cycle. This research shows that careful consideration of the road behavior of basalt fiber-reinforced asphalt mixture under freeze-thaw cycles and aging is essential for the pavement durability design.