Search Results (22)

With rising global temperatures and increasing sustainability demands, the need for advanced pavement solutions has never been greater. This study breaks new ground by integrating phase change materials (PCMs), including paraffin-based wax (Rubitherm RT55), hydrated salt (Climator Salt S10), and fatty acid (lauric acid), as binder modifiers within warm mix asphalt (WMA) mixtures. Moving beyond the traditional focus on binder-only modifications, this research utilizes recycled cigarette filters (CFs) as a dual-purpose fiber additive, directly reinforcing the asphalt mixture while simultaneously transforming a major urban waste stream into valuable infrastructure. The performance of the developed WMA mixture has been evaluated in terms of stiffness behavior using an Indirect Tensile Strength Modulus (ITSM) test, permanent deformation using a static creep strain test, and rutting resistance using the Hamburg wheel-track test. Laboratory tests demonstrated that the incorporation of PCMs and recycled CFs into WMA mixtures led to remarkable improvements in stiffness, deformation resistance, and rutting performance. Modified mixes consistently outperformed the control, achieving up to 15% higher stiffness after 7 days of curing, 36% lower creep strain after 4000 s, and 64% reduction in rut depth at 20,000 passes. Cost–benefit analysis and service life prediction show that, despite costing USD 0.71 more per square meter with 5 cm thickness, the modified WMA mixture delivers much greater durability and rutting resistance, extending service life to 19–29 years compared to 10–15 years for the control. This highlights the value of these modifications for durable, sustainable pavements. Full article

This study presents the results of using innovative and sustainable recycled fibers in different asphalt mixtures. Laboratory design and performance evaluation were focused on the cracking and rutting resistance of asphalt mixtures reinforced with recycled fibers. Two mixtures were designed for this research: 1. A dense-graded hot-mix asphalt (HMA) mixture containing 15% reclaimed asphalt pavement (RAP) and a PG 64-22 asphalt binder. 2. A cold-recycled mixture (CRM) incorporating silica fume and Portland cement as a mineral filler and CSS-1H asphalt emulsion. The recycled fibers used in this study included PET, LDPE, and carbon and rubber fibers. A balanced mix design (BMD) approach based on cracking and rutting performance parameters was used to design the control mixtures. The IDEAL-CT (ASTM D8225) was conducted to assess the cracking resistance, and the IDEAL-RT (ASTM D8360) was applied for rutting resistance. For the HMA mixture, results showed that the addition of PET, carbon, and rubber fibers enhanced cracking resistance and influenced the rutting resistance; ANOVA analyses revealed statistically significant differences in both CT index and RT index between the control mixture and the fiber-reinforced mixtures. In the case of the cold-recycled mixtures, the addition of LDPE, PET, and rubber improved cracking resistance; however, a decrease in rutting resistance was also observed among the evaluated CRM samples. Full article

Basalt fiber (BF) has been proven to be an effective additive for improving the properties of asphalt mixtures. However, the influence of basalt fiber morphology on the properties of asphalt binders and mixtures remains inadequately explored. In this study, chopped basalt fiber (CBF) and flocculent basalt fiber (FBF) were selected to make samples for testing the influence of the two types of basalt fibers on asphalt materials. Fluorescence microscopy was used to obtain the dispersion of fiber in asphalt binders. Then, a temperature sweep test and a multiple stress creep recovery (MSCR) test were carried out to appraise the rheological characteristics of the binder. Moreover, the performance of the fiber-reinforced asphalt mixture was evaluated by a wheel tracking test, a uniaxial penetration test, an indirect tensile asphalt cracking test (IDEAL-CT), a low-temperature bending test, a water-immersion stability test, and a freeze–thaw splitting test. The results indicate that the rheological behavior of asphalt binders could be enhanced by both types of fibers. Notably, FBFs exhibit a larger contact area with asphalt mortar compared to CBFs, resulting in improved resistance to deformation under identical shear conditions. Meanwhile, the performance of the asphalt mixture underwent different levels of enhancement with the incorporation of two morphologies of basalt fiber. Specifically, as for the road property indices with FBFs, the enhancement extent of DS in the wheel tracking test, that of R_T in the uniaxial penetration test, that of the CT_index in the IDEAL-CT test, and that of ε_B in the low-temperature trabecular bending test was 3.1%, 6.8%, 15.1%, and 6.5%, respectively, when compared to the CBF-reinforced mixtures. Compared with CBFs, FBFs significantly enhanced the elasticity and deformation recovery ability of asphalt mixtures, demonstrating greater resistance to high-temperature deformation and a more pronounced effect in delaying the onset of middle- and low-temperature cracking. Additionally, the volume of the air void for asphalt mixtures containing FBFs was lower than that containing CBFs, thereby reducing the likelihood of water damage due to excessive voids. Consequently, the moisture susceptibility enhancement of CBFs to asphalt mixture was not obvious, while FBFs could improve moisture susceptibility by more than 20%. Overall, the impact of basalt fibers with different morphologies on the properties of asphalt pavement materials varies significantly, and the research results may provide reference values for the choice of engineering fibers. Full article

Cracks in asphalt mixtures compromise the structural integrity of roads, increase maintenance costs, and shorten pavement lifespan. These cracks allow for water infiltration, accelerating pavement deterioration and jeopardizing vehicle safety. This research aims to evaluate the impact of synthetic fibers, specifically glass fiber (GF) and polypropylene fiber (PPF), on the crack resistance of Hot-Mix Asphalt (HMA). An optimal asphalt binder content of 5% was used in all sample designs. Using the dry mixing technique, GFs and PPFs were incorporated into the HMA at dosages of 0.50%, 1.00%, and 1.50% by weight of the aggregate. The effects of these fibers on the mechanical fracture properties of the HMA were assessed using Semi-Circular Bending (SCB), Indirect Tensile Asphalt Cracking Tests (IDEAL-CTs), and Three-Point Bending (3-PB) tests. This study focused on fracture parameters such as fracture work, peak load, fracture energy, and crack indices, including the Flexibility Index (FI) and Crack Resistance Index (CRI). The results from the SCB and IDEAL-CT tests showed that increasing GF content from 0.5% to 1.5% significantly enhances the flexibility and crack resistance of HMA, with FI, CRI, and CT Index values increasing by 247.5%, 55%, and 101.35%, respectively. Conversely, increasing PPF content increases the mixture’s stiffness and reduces its crack resistance. The PP-1 mixture exhibited higher FI and CT Index values, with increases of 31.1% and 10%, respectively, compared to the PP-0.5 mixture, based on SCB and IDEAL-CT test results. The SCB, IDEAL-CT, and 3-PB test results concluded that fibers significantly influence the fracture properties of bituminous mixtures, with a 1% reinforcement dosage of both PPFs and GFs being optimal for enhancing performance across various applications. Full article

The influence of surface modification on the properties of bagasse fibers and asphalt binders/mixtures was investigated. Bagasse fibers were modified by single, binary, and ternary methods with hydrochloric acid, sodium hydroxide, and sodium chlorite, respectively. The physical and chemical properties of bagasse fibers were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, and an adsorption test, respectively. The rheological properties of asphalt binders with bagasse fibers or lignin fibers were analyzed by the dynamic shear rheometer test and bending beam rheometer test. In addition, the performance of asphalt mixtures with bagasse fibers or lignin fibers were evaluated by a wheel rutting test, bending test at a low temperature, and water stability test, respectively. In conclusion, the hydrophilic functional groups on the fiber surface were partially eliminated by modification, facilitating the degradation of different fiber components. Furthermore, the degree of fibrillation was improved, and more interfaces with asphalt components were formed, thus enhancing the high-temperature deformation resistance of asphalt binders, but slightly impairing its low-temperature performance. Among all modification methods, the ternary composite modification exerted important influences on fiber structure, oil absorption, and rheological properties of asphalt binders, significantly enhancing the performance of asphalt mixtures. Combined with surface modification methods, bagasse fibers would be promising reinforced pavement materials. Full article

The bond strength between basalt fibers and asphalt binders is an important parameter that can be used to evaluate the influence of basalt fibers on the mechanical properties of asphalt binders and asphalt mixtures. To date, however, there remains a lack of methods that can be used to assess the bond strength between basalt fibers and asphalt binders. This study employed a fiber-asphalt pull-out tester (POT). Significant upward, peak, and downward stages were observed from the relationship curves between the pull-out force (POF) and displacement, corresponding to the holding stage and reaching the maximum POF stage and the sliding or failure stage between fibers and asphalt binders. Maximum POF is recommended to calculate the bond strength between basalt fibers and asphalt binders. The types of asphalt binders suitable for basalt fibers and the appropriate fiber embedding depths for different types of asphalt binders guiding the selection of fiber length are recommended based on the influence of fiber embedding depth and asphalt binders on the fiber–asphalt bond strength. In addition, surface energy was used to calculate the bond strength as well. Surface energy was determined from contact angle measurements using the sessile drop method. Furthermore, a scanning electron microscope (SEM) was employed to examine the bond mechanism between asphalt binders and basalt fibers. These experiments showed how basalt fibers serve to reinforce asphalt mixtures by bonding with asphalt binders. Full article

This study analyzed the viscoelastic properties of asphalt binders reinforced with various fibers, such as modified asphalt binder, modified asphalt binder reinforced with lignin fibers (LFs), polyester fibers (PFs), and polypropylene fibers (PPFs), using dynamic shear rheological (DSR) testing. Then, the experiment generated data on the dynamic modulus and phase angle, which described the dynamic rheological characteristics at varying temperatures. The generalized Maxwell model was employed to select the appropriate element, and the test curve was fitted into a discrete time spectrum based on the time–temperature equivalence principle (TTSP). The master curves of the relaxation modulus and creep compliance were established to predict the relaxation and creep properties of various asphalt binders. The analysis indicated that fiber-reinforced binders offer superior resistance to high temperatures and long-term deformation, while being less sensitive to temperature and having a more significant elastic characterization. The binders reinforced with PPFs and LFs exhibited superior performance in high-temperature settings and long-term durability, respectively. On the other hand, the binder reinforced with PFs displayed exceptional high-temperature elastic properties. Additionally, based on the experimental data and corresponding discussion, it appears that the 13-element GM model is more appropriate for fitting the data. Full article

The way we treat materials after their lifespan is changing. We are finding a new, more effective way to deal with waste: using it, rather than depositing it in landfills. Since bitumen mixtures are the most popular paving materials by far, and their lifespan is limited, there is a constant availability of old asphalt pavement or reclaimed asphalt (RA). To restore the aged binder properties, we can use recycling agents. In this study, two commercialized biobased recycling agents were used. Furthermore, jute fibers were used as a reinforcement. The influence of the different fiber content and fiber length was investigated in mixtures without the recycling agents. In addition, alkali-treated fibers were used in some mixes for better fiber compatibility with the bitumen matrix. Air voids content, moisture, freeze–thaw susceptibility, stiffness modulus (IT-CY), resistance to crack propagation, and complex modulus tests were conducted. The addition of recycling agents led to a decrease in stiffness. A lower indirect tensile strength ratio (ITSR), increased stiffness, and best crack propagation results were recorded in some mixtures with fibers and recycling agents. Full article

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. Full article

Open-graded bituminous concrete (OGBC), also known as open-graded friction course or permeable asphalt layer, is a skid-resistant surface applied to pavements with high bitumen content. This mixture contains more coarse aggregates than fine aggregates, which improves subsurface drainage and indirectly reduces hydroplaning potential during wet weather conditions. The objective of the present study was to enhance the properties of the OGBC mix with fibers. Hence, four distinct natural biofibers, namely, sisal fiber, jute fiber, coir fiber, and bamboo fiber, were considered during experimental investigation at different dosages like 0.15%, 0.3% & 0.45% by weight of mix. Binder content levels ranged from 5 to 6% with an increment of 0.25% between the values in the range. Fiber-reinforced OGBC mixes were tested for air voids (%), draindown, resistance to moisture susceptibility, Cantabro loss, and indirect tensile strength of the compacted mixtures. The experimental findings demonstrate that fibers enhance the performance of OGBC mixes. Fiber incorporation reduced binder draindown and the percentage of air voids in OGBC mixes while maintaining the desired characteristics. The optimal fiber content was determined to be 0.30% for sisal, bamboo, and coir fibers and 0.45% for jute fibers. With the addition of sisal fibers at a dosage rate of 0.30%, the tensile strength of the OGBC mixture increased along with resistance to susceptibility to moisture. Full article

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. Full article

In order to evaluate and improve the deformation behavior of cement–emulsified asphalt binder (CA) in cement–emulsified asphalt mixture, this study investigated the reinforcement of small additions of fibers (2%, 4%, and 6% addition by mass of cement) on the deformation resistance of CA. A repeated creep recovery test was implemented that measures the recovery rate of creep deformation and accumulated strain. Further, an improved piecewise curve-fitting method was used to determine the parameters of Burgers model, then the creep compliances were fitted and calculated. The results show the repeated creep recovery test to be a suitable method for obtaining useful information about creep and recovery deformation of fiber-reinforced CA. The influence of fiber types and dosages on the deformation recovery ability is determined based on the creep recovery ratio and accumulated strain. The improved piecewise curve-fitting method has high accuracy. Thereafter, the reinforcement effect was analyzed through the evolution of creep compliance under loading. Therefore, this paper can provide a reference for enhancing the properties of cement–emulsified asphalt mixture by maximizing the fiber reinforcement. Full article

Fiber-reinforced asphalt concrete (FRAC) was tested using limestone, PG 64-22 binder, and 20% reclaimed asphalt pavement (RAP). After mixing fibers with different lengths and dosages, they were extracted and recovered to evaluate their dispersion in the FRAC. The uniaxial fatigue test, IDEAL CT test, and flow number test were performed on FRAC with different fiber lengths and asphalt contents. The balanced mix design (BMD) approach was then used to analyze the uniaxial and flow number test results in order to evaluate the effect of aramid fibers on fatigue and rutting resistance of the pavement. The dispersion test showed that the 19 mm and 10 mm aramid fibers at a dosage rate of 0.5 g/kg provided the best dispersion. The 19 mm fibers showed better performance test results than the 10 mm and 38 mm fibers. The BMD approach provided ranges of asphalt contents to produce mixes with certain resistances to fatigue and rutting. The BMD approach also demonstrated the effect of fibers with different lengths on increasing the resistance to fatigue and rutting. The study concluded that the 19 mm fibers with a dosage of 0.5 g/kg produce best results. The BMD approach is a good tool that can be used to refine the mix ingredients, including additives such as fibers, in order to optimize pavement resistance to various distresses such as fatigue cracking and rutting. Full article

This study aims to maximize the effects of reducing plastic deformation in heavy traffic intersections in urban areas by improving the aggregates and binders of asphalt mixtures in order to verify the strength effect of SMA (Stone Mastic Asphalt) mixtures compared with that of fluid-resistant asphalt mixtures. The authors examine the pavement performance and conduct an economic analysis for sustainable urban infrastructure. Additionally, to reduce plastic deformation, the study analyzed an improvement plan through experimental research based on the existing literature. First, we determined the mixing design specifications of the general asphalt fluid-resistant mixture and SMA mixture, which is known to reduce plastic deformation. Next, we confirmed the appropriateness of the raw materials and mixing design results. Finally, a performance test was conducted on plastic deformation resistance. A wheel tracking test was also conducted as a performance experiment. The test body—with a fiber grid reinforcing material installed in the SMA mixture—showed high dynamic stability, which was the most effective for reducing plastic deformation. Full article

There is an increasing global trend to find sustainable, environmentally friendly and cost-effective materials as an alternative to limited natural raw materials. Similarly, the use of waste materials has been gaining popularity in the production of hot-mix asphalt (HMA). In this study, the sustainable use of glass-fiber-reinforced polyester (GRP) pipe waste powder (GRP-WP), gathered from the cutting and milling process of GRP pipe production, utilizing it in asphalt mixes as a filler, is evaluated based on lab testing to find out: (i) if it produces similar or better performance compared to the most conventionally available filler material (limestone) and, (ii) if so, what would be the optimum GRP-WP filler content to be used in asphalt mixes. For this reason, an experimental test matrix consisting of 45 samples with three different amounts of binder content (4%, 4.5% and 5.0%), and a 5% filler content with five different percentages of the GRP-WP content (0%, 25%, 50%, 75% and 100% replacement by weight of the filler), was prepared to figure out which sample would produce the similar Marshall stability and flow values compared to the control samples while also satisfying specification limits. It was found that the samples with 4.5% binder content, 3.75% GRP-WP and 1.25% limestone filler content produced the results both satisfying the specification requirements and providing an optimum mix design. It is believed that use of GRP-WP waste in HMA production would be a very useful way of recycling GRP-WP. Full article