Fiber length is a key parameter for the mixture design of basalt fiber-reinforced hot mix asphalt (HMA), which significantly affects the mix performance. To evaluate the suitability of fiber lengths ...for HMA with different nominal maximum aggregate size (NMAS), basalt fiber with the lengths of 3, 6, 9, 12, and 15 mm were selected for dense graded gradations with different NMASs (namely, SUP-13, SUP-20, and SUP-25), so as to prepare the fiber-reinforced HMA mixtures. Then, the mix performance was evaluated by an indirect tensile asphalt cracking test (IDEAL-CT), a four-point bending beam fatigue test, a wheel tracking test, a uniaxial penetration test, a low temperature bending beam test, and a freeze-thaw splitting test. Based on the performance results, the optimum fiber length for each mix gradation was proposed by the normalization method. The results showed that adding basalt fiber can enhance the comprehensive performance of all three types of HMA to a great extent. Furthermore, fiber length presented remarkable impact on the crack resistance, the fatigue resistance of the HMA, and the low temperature crack resistance, but it had limited influence on the high temperature deformation resistance, and water stability. The optimum fiber length for SUP-13, SUP-20, and SUP-25 was 6, 9, and 12 mm, respectively.
In this study, basalt fiber having two types of diameters (16 μm and 25 μm) was selected and added to asphalt mastic and asphalt mixtures using different fiber proportions. The influences of fiber ...diameters and proportions on the properties of asphalt mastic and mixtures were studied. The adhesion behavior of the fiber-asphalt mastic (FAM) interface was evaluated by a monofilament pullout test, and the rheological properties of FAM were evaluated by temperature sweep, linear amplitude sweep, and bending beam rheological tests. In addition, the high-temperature stability, intermediate and low-temperature cracking resistance, and water stability of fiber-modified mixtures were studied by wheel tracking, ideal cracking, a low-temperature bending beam, and a water-immersed Marshall test. The results showed that the interface adhesion behavior between 16 μm fiber and asphalt mastic was more likely in the fiber failure mode at both −12 °C and 25 °C. Adding basalt fiber can significantly improve the high-temperature and fatigue properties of asphalt mastics. Moreover, 16 μm fiber had a better modifying effect on asphalt mastic than 25 μm fiber. The same enhancement trend can be observed in asphalt mixtures. Basalt fibers with 16 μm diameters can improve the high-temperature performance of asphalt mixtures more significantly. In addition, 16 μm fiber could sharply enhance the cracking performance of the mixtures at intermediate and low temperatures, while the enhancing effect of 25 μm fiber on the mixture is insignificant, though both diameters of the fibers have a minor effect on the water stability.
In the context of green and low-carbon development, energy saving, and emission reduction, hot recycling technology (RT) has been researched, which is divided into hot central plant RT and hot ...in-place RT. However, due to the aged asphalt binders, the shortcomings of hot recycled asphalt mixtures have become apparent, as in comparison to new asphalt mixtures, their resistance to cracking was inferior and the cracking resistance deteriorated more rapidly. Therefore, it was very necessary to focus on the improvement of crack resistance of hot recycled asphalt mixtures. Basalt fiber has been proved to be able to effectively improve the comprehensive road performance of new asphalt mixtures. Therefore, this paper introduced basalt fiber to hot central plant recycled and hot in-place recycled asphalt mixtures, in order to improve the crack resistance of asphalt as a new type of fiber stabilizer. Firstly, six types of SMA-13 fiber asphalt mixtures were designed and prepared, i.e., hot mixtures with basalt fiber or lignin fiber, hot central plant recycled mixtures with basalt fiber or lignin fiber, and hot in-place recycled mixtures with basalt fiber or lignin fiber. Secondly, the trabecular bending test, low-temperature creep test, semi-circular bending test, and IDEAL-CT were used to comparatively study the changing patterns of low and intermediate temperature cracking resistance of hot recycled mixtures with conventional lignin fibers or basalt fibers. Finally, Pearson's correlation coefficient was used to analyze the correlation of the different cracking resistance indicators. The results show that the low and intermediate temperature cracking resistance of hot central plant recycled mixtures increased by 45.6% (dissipative energy ratio,
/
) and 74.8% (flexibility index, FI), respectively. And the corresponding cracking resistance of hot in-place recycled mixture increased by 105.4% (
/
) and 55.7% (FI). The trabecular bending test was more suitable for testing the low-temperature cracking resistance of hot recycled asphalt mixtures, while the IDEAL-CT was more suitable for testing the intermediate-temperature cracking resistance. The results can provide useful references for the utilization of basalt fiber in the hot recycling of SMA-13 asphalt mixtures.
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.
Many researchers use fiber to improve the cracking resistance of asphalt mixtures, but research concerning the effects of fiber on fracture behavior is limited. The fracture behavior of asphalt ...mixtures with various fiber types (basalt fiber, glass fiber, and polyester fiber) and contents (0.1%, 0.2%, 0.3%, 0.4%, and 0.5%) has been studied using the indirect tensile asphalt cracking test (IDEAL-CT) in conjunction with digital image correlation (DIC) technology. The evaluation indexes used in the test included crack initiation energy (Gif), crack energy (Gf), splitting tensile strength (RT), cracking tolerance index (CTindex), and the real-time tensile strain (Exx) obtained using digital image correlation technology. The results showed that despite the fiber type, the increase of fiber content resulted in first, an increase, and then, a decrease of the cracking resistance of asphalt mixtures, indicating the presence of optimum fiber content—specifically, 0.4%, 0.3%, and 0.3% for basalt fiber, glass fiber, and polyester fiber, respectively. The development of real-time tensile strain, obtained based on digital image correlation technology, could be divided into two stages: slow-growth stage and rapid-expansion stage. In addition, asphalt mixture with basalt fiber presented the best cracking resistance at both the slow-growth and rapid-expansion stages. This research is helpful in understanding the effects of fiber type and content on the fracture behavior of asphalt mixtures and has certain reference significance for the application of fiber in asphalt mixtures.
Fiber has an important influence on the performance of asphalt materials. However, the effect of fiber characteristic parameters (length, type, etc.) on the function of asphalt mortar is still lack ...of understanding. Therefore, a systematical experimental plan was conducted to evaluate the effects of the selected parameters of filler-binder ratio, fiber type, fiber content and fiber length on the rheological properties of asphalt mortar, including five filler-binder ratios (0.6, 0.8, 1.0, 1.2 and 1.4), four fiber types (three chopped basalt fibers with different coating agents named A, B and C and one flocculent basalt fiber), five fiber contents (1%, 2%, 3%, 4% and 5%) and three fiber lengths (6 mm, 9 mm, 15 mm). Then, Dynamic Shear Rheological (DSR) tests and Bending Beam Rheological (BBR) tests were employed to evaluate the rheological behavior of each asphalt mortar. The corresponding reinforcing mechanism was subsequently analyzed by Environmental Scanning Electron Microscope (ESEM) test. The results show that basalt fiber can obviously enhance the high-temperature rheological properties of asphalt mortars, while strengthen the stress dissipating ability at low temperatures to some extent. Besides, the fiber type, fiber content and fiber length all impact the rheological properties of asphalt mortars. The asphalt mortars with type A basalt fiber present the superior rheological performance at both high and low temperature, with the optimum fiber content of 2% and fiber length of 9 mm, respectively. The test results of ESEM reveals that basalt fiber shows spatial distribution in asphalt mortar, presenting the function of stabilization and reinforcement.
A new type of plastic and basalt fiber composite (PB) modifier, which is composed of waste plastic and basalt fiber using a specific process, was used for bus lanes to address severe high-temperature ...deformation diseases due to the heavy loads of buses. The dense gradations of asphalt mixture with a nominal maximum aggregate size of 13.2 mm (AC-13) and 19 mm (AC-20) were selected to fabricate asphalt mixtures. The impact of the modifier PB on the high-temperature rutting resistance, low-temperature crack resistance, and water damage resistance was investigated experimentally. The experimental results showed that adding the modifier PB could enhance the rutting resistance and water damage resistance of asphalt mixtures significantly while maintaining the low-temperature crack resistance. Then, PB-modified asphalt mixtures of AC-13 and AC-20 were employed into a typical pavement structure of a bus lane in Yangzhou city, China, and three types of designed pavement structures were proposed. On this basis, statics analyses of all of the designed structures were performed using the finite element method. The statics analyses revealed that, compared with the standard axle load, the actual over-loaded axle made the pavement structure of the bus lane suffer a 30% higher stress and vertical deformation, leading to accelerated rutting damage on the bus lanes. The addition of the modifier PB could make the pavement structure stronger and compensate for the negative effect caused by the heavy axle load. These findings can be used as a reference for the pavement design of urban bus lanes.
Incorporating reclaimed asphalt pavement (RAP) into asphalt mixtures achieves astonishingly environmental and economic benefits. However, there is hesitation to use higher RAP content due to the ...concern regarding the deterioration in pavement performance, especially the cracking resistance. Basalt fiber has been considered an effective additive to reinforce the performance of asphalt mixtures and, subsequently, the reinforcement effect is also expected for high-RAP content mixtures. Therefore, this study investigated the effect of basalt fiber on the pavement performance of asphalt mixtures with 0%, 30%, 40%, and 50% RAP contents against high-temperature performance, moisture susceptibility, low-temperature and intermediate-temperature cracking resistance, based on the wheel-tracking test, the uniaxial penetration test, the freeze-thaw splitting test, the low-temperature bending beam test, the semicircular bend fracture test and the indirect tensile asphalt cracking test, respectively. In addition, a performance-space diagram was developed to determine the mixture performance shift caused by basalt fiber. The results showed that adding basalt fiber compensated for the detrimental effect caused by RAP, leading to significant enhancement in moisture susceptibility and low- and intermediate-temperature cracking resistance of mixtures with high RAP content, along with the enhancement in high-temperature performance, indicating that basalt fiber can contribute to the use of high RAP content.
Non-renewable resources such as natural stone and asphalt are in short supply. Recycling technology, with its lower cost, has been used as the primary approach to asphalt pavement maintenance ...engineering. The inclusion of reclaimed asphalt pavement materials in producing new asphalt pavements may increase the risk of cracking. The strength and toughness of the asphalt mixture can be reduced. In this study, Hamburg wheel tracking tests (HWTT) were performed on rejuvenated asphalt mixtures with distinct maintenance processes. Different kinds of fibers have been used as additives to reinforce the rejuvenated asphalt mixtures. The HWTT rutting curve was identified as having three stages, including the post-compaction stage, the creep stage, and the stripping stage. The three-stage rutting curve model was used to determine the intersection point between the creep stage and stripping stage. The other two feature points (i.e., the post-compaction point and the stripping inflection point) were redefined with a new calculation method. Then, the rutting effect and stripping effect were separated with these feature points. The performance and economic benefits of fiber-reinforced rejuvenated asphalt mixtures were investigated through grey correlation analysis under the three maintenance processes. The feature points of the HWTT curve and the cost of the corresponding maintenance process were selected as the impact factors. Finally, the optimal scheme was developed by analyzing the influence of each factor on both performance and economic benefits.
Reclaimed asphalt pavement (RAP) has been widely utilized because it is an environmentally friendly and economical material. The performance of recycled asphalt mixtures will deteriorate gradually ...with the secondary aging process of asphalt, including the self-healing property. To further understand the self-healing characteristics of asphalt after secondary aging, taking 70# petroleum asphalt, SBS-modified asphalt, and extracted old asphalt mastics as objects, the fatigue self-healing test and fracture self-healing test were conducted to simulate the intermediate-and low-temperature healing behaviors of different asphalt mastics. The impact of healing time, healing temperature, and aging degree of mastics on the healing performance was systematically investigated. The results show that the original unaged asphalt mastics present excellent fatigue healing properties with an index of 0.796 and 0.888 for 70# petroleum and SBS-modified asphalt mastics, respectively. The secondary aging process causes significant impact on the healing properties, leading to a great drop in the corresponding index, which decreased to 47.5% and 72.5% of that of the unaged ones. The fracture healing ability of all mastics was much inferior to the fatigue healing. After secondary aging, the fracture healing index values of 70# petroleum asphalt, SBS-modified asphalt, and extracted old asphalt mastics were all as low as around 0.3, indicating similar performance can be found in the secondary aged SBS-modified asphalt mastics and 70# asphalt mastics. Overall, after secondary aging, the fatigue damage of SBS-modified asphalt mastics can be cured effectively by self-healing, but the fatigue and fracture self-healing properties of 70# asphalt mastics are difficult to recover. These results could provide an innovative view to understand the fatigue and fracture healing characteristics of recycled asphalt pavement after secondary aging.
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