Performance Of Asphalt Mixtures Research Articles

The Performance of Modified Asphalt Mixtures with Different Lengths of Glass Fiber

AbstractOne practical option for modifying an asphalt mixture’s performance is to use additives. This will help the mixture perform better against the damaging effects of traffic, loads, and climatic variations. In this regard, glass fiber (GF) has drawn much interest because of its positive effect. Therefore, this paper attempts to study the effect of glass fiber length and content on the performance and strength of asphalt mixtures. It also aims to determine the optimum glass fiber content and the best glass fiber length of modified asphalt mixtures. An experimental program is carried out, which includes the Marshall test, volumetric properties, freeze-thaw splitting test, immersion Marshall test, and wheel tracking test to characterize related properties of glass fiber incorporated in asphalt mixtures. Seven different percentages (0, 0.25, 0.5, 0.75, 1, 1.25, and 1.5) of glass fiber by total weight of aggregates in three various lengths are used to design 19 asphalt mixtures. Based on the results obtained, the performance of the asphalt mixture was enhanced remarkably after adding glass fiber. The use of various lengths of glass fiber led to a better-quality asphalt mixture in terms of volumetric properties, moisture damage resistance, and permanent deformation resistance. Specifically, asphalt mixtures made with (0.5%) glass fiber illustrated the highest quality, and adding (20 mm) length of glass fiber was better than (10 mm and 30 mm) glass fiber lengths. The results also show that adding (10 mm and 30 mm) lengths of glass fiber can improve the resistance of asphalt mixtures to water damage and permanent deformation compared with the control mixture (M0). The findings indicate the applicability of 20 mm glass fiber length in asphalt mixtures to achieve better resistance against moisture and reduce the chance of irreparable permanent deformation under growing traffic loads and hot climate changes. Although the inclusion of glass fiber in asphalt mixtures led to a modest increase (6%) in overall cost, the effective improvement in performance and extension of the service life of the asphalt pavement constitute a convincing argument for this approach, making it an attractive option. Finally, it was concluded that a higher amount of glass fiber (i.e., > 0.5%) and a length greater than (20 mm) could diminish the positive effect of glass fiber to improve the properties of glass fiber asphalt mixtures.

Investigation of Surface Modification of Bagasse Fibers: Performance of Asphalt Binders/Mixtures with Bagasse Fibers

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.

Porous asphalt mixture performance in cold regions: Case study of Chicago

Porous Asphalt Mixtures (PAMs) improve resilience of flexible pavements in the context of climate change. PAM application in coastal cities like Chicago is of interest; however severe winters compromise the durability of PAMs given their susceptibility to freeze-thaw. This work aimed to evaluate the to-date experience with PAMs in Chicago, exploring benefits and limitations to be considered for future projects in the Southern Lake Michigan region. Full-depth PAM cores were obtained from seven sections, constructed in different years. Tests were conducted to assess the evolution of surface texture, internal structure, and multi-scale material properties. Regarding surface texture, consistent change over time was observed, such as loss of the “channel” structure, and increase in mean profile parameters because of raveling. Also, binder content varies with time within different layer depths. An aging gradient in terms of stiffness from top to bottom within the layer does not necessarily occur. However, binder ductility shows drastic and consistent reduction throughout the layer as aging increases. Analysis of internal structure using a CT scan revealed that there is also a lack of homogeneity in the air void and particle size distributions. Finally, this study suggests that full-depth PAM viscoelastic behavior is sensitive to saturation level, and this is a relevant subject to be considered, since partial saturation may be a condition often observed in the field.

Multi-criteria analysis of porous asphalt mixtures with aramid fiber under adverse conditions

This study the functional performance of super porous asphalt mixtures with two types of aramid fibers against adverse events during their service life. This research was organized in 4 phases: first, particle loss after extreme weather conditions was evaluated. Second, the permeability and clogging resistance was assessed. Third, its resistance to fuel spillage was studied. Fourth, a multi-criteria analysis was performed to determine the best performing mixture considering all the studied variables.Regarding the results, mixture with aramid and polyolefin was the best performing blend according to the multi-criteria analysis. The fiber content allowed for acceptable performance in terms of particle loss despite having a higher void content than the reference mixtures. In addition, a higher permeability and clogging resistance was found, so the use of such fibers did not negatively affect the internal structure of the mixture. Finally, it had a higher resistance to fuel spillage due to the use of polymer-modified bitumen.

Evaluating the effect of paper waste lignin in hot mix asphalt

Asphalt is a viscoelastic material which performs to resist rutting, fatigue cracking, and moisture susceptibility under different loading and temperature conditions. The use of innovative and renewable pavement construction materials is inevitable due to high axle loads, rapidly increasing traffic volumes, and varying climatic conditions. This study aims to assess the effect as well as the optimum dosage of paper waste lignin for use in hot mix asphalt (HMA). Lignin from the paper industry with dosage ratios of 5, 10, 15, and 20%, was utilized to study the effect of the addition of lignin to the asphalt binder. Virgin and lignin-modified binder samples, before and after the aging process, were subjected to physical testing through penetration, softening point, ductility, viscosity and specific gravity and rheological characteristics through dynamic shear rheometer (DSR), bending beam rheometer (BBR), and rational viscometer (RV). The fractional composition was assessed through saturates, aromatics, resins and asphaltenes (SARA) fractional composition technique. Statistical analysis was also performed to find correlation of different physical and rheological parameters. Furthermore, based on optimum dosage, the performance of asphalt mixtures was studied against rutting, fatigue cracking, and moisture susceptibility. The results indicated that the addition of lignin has improved the physical properties significantly. The amount of asphaltene decreased and aromatics increased in SARA fractional analysis. Moreover, the Colloidal Instability Index (CII) has also indicated a stable structure of the binder. The rheological characteristics are improved after modification. The asphalt mixture tests revealed that addition of lignin with optimum dosage (10%) has improved the performance against rutting, fatigue cracking and moisture susceptibility. Statistical analysis indicated good co-relation among different physical and rheological parameters. This study concludes that 10% dosage is the optimum dosage that can successfully replace the virgin asphalt binder for performance of hot mix asphalt.

Preparation and Performance Evaluation of Castor Oil-Based Asphalt Regeneration Agent.

Regeneration agents play a critical role in modifying the mechanical properties and durability of RAP asphalt mixtures. This paper aimed to develop a castor oil-based asphalt regeneration agent. The effects of this regeneration agent on the pavement performance of laboratory-aged asphalt and an RAP asphalt mixture were comparatively studied by a series of laboratory tests. For the developed castor oil-based asphalt regeneration agent, the weight ratio of the castor oil to dibutyl phthalate was determined as 1:4. Moreover, the regeneration effectiveness of the castor oil-based regeneration agent was tested on three laboratory-aged asphalt binders and an RAP asphalt binder; the penetration, softening point and ductility of the RAP asphalt binder recovered to 83 dmm, 50.3 °C, and more than 100 cm, respectively. The optimum content of the regeneration agent was 5% by the weight of the aged asphalt binder. Furthermore, the castor oil-based regeneration agent could effectively restore the pavement performance of an RAP asphalt mixture. In this study, the RAP percentage can reach up to 60% by the weight of the HMA mixture using the castor oil-based asphalt regeneration agent according to the Chinese specification.

A Review of the Studies on the Effect of Different Additives on the Fatigue Behavior of Asphalt Mixtures

The fatigue phenomenon significantly weakens road pavement due to repeated reloading. To enhance fatigue resistance, numerous studies have explored various additives in asphalt mixtures. This review focuses on key variables influencing the effectiveness of additives, including fibers, polymers, nanomaterials, waste materials, and biomaterials, in improving the fatigue performance of asphalt mixtures. The study initially identifies different additives and fatigue testing methods used for asphalt mixtures. It evaluates the impact of factors such as modifier content and size, base asphalt binder type, mixing processes, dispersion behavior, and testing conditions on the fatigue behavior of modified asphalt mixtures. The cost-effectiveness and environmental impact of additive application have also been assessed. Additionally, research gaps and future prospects for modified asphalt mixes are outlined. Existing studies demonstrate the benefits of additives like basalt fiber, polyester fiber, styrene–butadiene–styrene (SBS), nanosilica, crumb rubber, and biooils in enhancing the fatigue life of pavement constructions. However, challenges exist in the application of modifiers due to limited practical implications and insufficient knowledge. Further research is needed on factors such as additives’ dispersity, compatibility, aging resistance, economic viability, and modifying mechanisms in morphological and micromechanical aspects to enhance the fatigue performance of the modified asphalt mixture.

Research on deicing performance and environmental impact of anti-freezing asphalt mixtures

Snow and ice on pavement surface can cause a significant safety concern for drivers. This research investigates the deicing performance of the asphalt mixtures containing a self-prepared salt-storage additive (SSA), as well as their environmental impacts. A pull-off test was developed to evaluate the adhesion between the ice layer and asphalt mixture surface. The self-prepared SSA was incorporated into the asphalt mixtures by replacing mineral filler at percentages of 0 %, 20 %, 50 %, and 100 % by volume. The influence of self-prepared SSA on the pavement performance of asphalt mixtures was firstly investigated in this study, including the high-temperature stability, low-temperature performance, and water stability. The deicing performance of the asphalt mixtures containing self-prepared SSA and commercial product was determined by using the freezing point tests, ice-melting tests, and self-designed pull-off tests. To evaluate the environmental impacts of those anti-freezing asphalt mixtures, corrosion tests and seed germination tests were also employed in this study. Testing results showed that the addition of self-prepared SSA compromised the pavement performance of asphalt mixtures, but all measured properties met the specified requirements. The self-prepared SSA can effectively reduce the freezing point of the asphalt mixtures and shorten the ice melting time by 30 %, which has a similar or even better deicing effect as compared to the commercial salt-storage additive. Notably, the pull-off tests showed that the self-prepared SSA can significantly reduce the adhesion force between ice layer and asphalt mixture surface. The environmental impacts of asphalt mixtures containing self-prepared SSA were found to be within a reasonable range.

Bio-graded recycling for hot asphalt mixtures with high RAP content considering freeze-thaw

This paper investigates the effects of freeze-thaw cycles on the performance of asphalt mixtures containing 60% rejuvenated asphalt pavement (RAP). Two rejuvenation processes, traditional and bio-graded recycling, are compared regarding high-temperature performance, low-temperature performance, dynamic stability, flexural tensile strength, split tensile strength, water stability, and fatigue performance after various freeze-thaw cycles. The results indicate that bio-graded rejuvenation, compared to traditional rejuvenation, effectively enhances the high-temperature performance, low-temperature performance, water stability, and fatigue performance after freeze-thaw cycles. Both rejuvenations initially meet the dynamic stability requirements but show a decreasing trend with increasing freeze-thaw cycles, with traditional rejuvenation exhibiting more severe degradation. The flexural tensile strength initially exceeds that of conventional asphalt mixtures but decreases significantly with freeze-thaw cycles, especially in traditional rejuvenation. Additionally, freeze-thaw action increases the internal void ratio, affecting water stability and anti-freezing ability, particularly in traditional rejuvenated mixtures. These findings underscore the impact of freeze-thaw cycles on rejuvenated asphalt mixtures and emphasize the importance of innovative rejuvenation techniques for sustainable pavement.

Development of an asphalt mixture with polymer incorporation modified by industrial graphene nanoplatelets for high-performance to rutting

ABSTRACT This study aimed to develop a high-performance asphalt mixture resistant to rutting through modification with industrial-scale graphene nanoplatelets (industrial GNPs). To achieve this objective, industrial GNPs were incorporated into an SBS-modified asphalt binder at concentrations of 2%, 4%, 6%, 8%, and 10% by mass of the asphalt binder. The aim was to select a design content to enhance the rutting performance of the resulting asphalt mixture. The nanomaterial content selection criterion was based on apparent viscosity results and rheological parameters (MSCR). Two asphalt mixtures were produced after determining the nanomaterial content: a reference mixture and another modified by the selected content (2.64% of industrial GNPs). The mechanical performance was assessed through resistance to rutting tests on French Orniéurer equipment and, in a secondary character, the fatigue resistance under four-point bending. The results showed better rheological behaviour of the modified composites than of the original binder, decreasing the viscous response at high temperatures and thus reducing the non-recoverable deformations. The resistance to rutting of the modified mixture exceeded that of the reference mixture by 19% (mean rut for 30,000 cycles) without significant damage to the fatigue life, proving the high rutting performance of the alternative asphalt mixture.

Low-temperature crack resistance of stone matrix asphalt mixtures under chloride salt dry-wet cycles

Given the current insufficient understanding of the low-temperature crack resistance performance and crack evolution patterns of asphalt mixtures under chlorinated salt wet-dry coupling environments, this study aims to fill this knowledge gap. We employed SMA-13 asphalt mixtures modified with different dosages of polyester fibers (0 %, 0.3 %, 0.35 %, 0.4 %, 0.45 %, 0.5 %) and tested their low-temperature crack resistance by conducting 0 to 8 wet-dry cycles in pure water and a 13.25 % chlorinated salt solution, to explore the improvement effect of polyester fibers on the performance of asphalt mixtures in such environments. The results indicate that an increase in the number of wet-dry cycles leads to a degradation of crack resistance performance across all fiber dosages, especially under the influence of chlorinated salt wet-dry coupling, where the adverse effects are more pronounced. Fracture energy analysis further confirms that 4 and 6 cycles of wet-dry cycling are effective indicators for evaluating the attenuation of low-temperature crack resistance under the long-term impact of wet-dry cycling. Through Digital Image Correlation (DIC) and Scanning Electron Microscopy (SEM) analyses, this study reveals the significant impact of wet-dry cycling on crack evolution and identifies 0.4 % as the optimal dosage of polyester fibers, significantly enhancing the low-temperature crack resistance performance of asphalt mixtures.

Evaluation of the effect of different preparation processes on the road performance of thermoplastic resin modified porous asphalt mixtures

In order to evaluate the effects of three preparation processes, namely dry process (DP), wet process (WP) and wet/dry mixing process (MP), and resin high viscosity modifier (RHVM) on the road performance of porous asphalt mixtures, the frequency scanning, multi-stress creep recovery, and bending beam rheometer tests were used to analyze the rheological performance of resin-modified high viscosity asphalt under different processes. Uniaxial compression, Wheel tracking, Semi-circular bending and Freeze-thaw indirect tensile tests were used to test the properties of resin-modified porous asphalt mixtures under different processes. The commonly used TAFPACK-Super (TPS) modifier was a control group. Finally, the changes in the microscopic morphology characteristics and chemical composition were used to illustrate the enhancement mechanism of resin modifiers. The results showed that the high-temperature deformation resistance and low-temperature cracking resistance of RHVM modified asphalt prepared by DP and MP are weaker than that of the WP. Compared to the RHVM(WP), the Jnr(3.2) of RHVM(DP) and RHVM(WP) decreased by 14.3% and 63.8%, the strength modulus of RHVM(DP) and RHVM(MP) increased by 21.5%, 28.0% and the creep rate decreased by 2.37%, 4.45%, respectively. As for the performance of asphalt mixture, compared to the RHVM(WP) asphalt mixture, the dynamic stability of RHVM asphalt mixture prepared by the DP and MP decreased by 17.3–18.2%, σs and εs of RHVM(DP) and RHVM(MP) increased by 15–35% and 21–29%, respectively. The water stability of RHVM(DP) asphalt mixtures was better than that of RHVM(WP) when the mixing time reached 180 s. RHVM(WP) asphalt mixtures have superior low-temperature cracking resistance, comparable water stability, and slightly poorer high-temperature stability than that of TPS(WP) asphalt mixture. Microscopic morphology observation found that some modifier particles and asphalt binder did not realize effective mixing under the DP and MP, and infrared spectroscopy results confirmed that TPS modifiers are mainly physically co-mingled with asphalt, while the tackifier resin in the RHVM reacts with the asphalt to form new functional groups to increase the viscosity of the asphalt.

Effect of wet-dry history on performances of dense asphalt mixture: Experimental investigation and predicting model

Asphalt pavement experiences various wet-dry histories in the service stage. However, the influence of wet-dry history on asphalt mixture is unknown. Therefore, to clarify the performance degradation mechanism and predict the performance of asphalt mixture under the action of wet-dry history, the creep-recovery test, indirect tensile stiffness modulus test and indirect tensile strength test were conducted at different temperatures. The finite element method was adopted to analyze the moisture diffusing profile inside the specimen after wet-dry cycles. A moisture damage model considering the soaking time and repeated characteristics was developed to predict the damaged properties. Results show that wet-dry cycles cause a slight mass loss of asphalt mixture. Wet-dry cycling action leads to the increment in high-temperature deformation, and reductions in stiffness modulus and tensile strength. The increase of high-temperature deformation is primarily caused by viscoplastic component. Even if the soaking time is short, high moisture damage occurs while the wet-dry cycle is sufficient. Numerical simulations show that the moisture concentration profiles inside asphalt mixture vary under different wet-dry histories, leading to variations in the damage zone. The degree of damage is also closely related to the acting time of moisture. The critical immersion time of the dense asphalt mixture (about 43 hours) was determined in this study. When the immersion period is shorter than the critical immersion time, the strength loss is greater than the modulus. On the contrary, the degree of modulus damage is higher than that of strength. Considering the actual rainfall climate in China, the strength damage of the on-site asphalt mixture in the field predominates. The proposed model could reflect the weakening trends of modulus and strength. It has good universal applicability in predicting the damaged Marshall stability, modulus, and strength at different temperatures.

Effects of short-term aging on the mechanical and structural performance of hot mix asphalt mixtures: a case study complemented by statistical analysis

This study aimed to assess the effects of short-term aging on the mechanical behaviour of asphalt layers of flexible pavement structures. The effects of aging on their mechanical performance have not yet been detailed, in terms of structural analyses. Therefore, pavement structures with distinct types of asphalt layers (non-aged and aged) were evaluated. Stability, tensile strength, resilient modulus, fatigue behaviour and permanent deformation or static creep were determined. The mePADS software was used to carry out structural analyses of the pavements, based on variations in the bound layers’ mechanical properties, loading level and tire inflation pressure. Horizontal stresses and strains were determined at the bottom of the binder course. Fatigue lives were predicted and discussed based on statistical analyses. The short-term aging enhanced the mechanical parameters, but adversely affected the fatigue life for the examined strain states, which reinforces the importance of carrying out the structural analyses.

Mechanical Properties and Performance of Mixtures Containing a High Level of Recycled Materials That Are Designed Using Alternative Approaches

Using recycled asphalt material (RAM) in asphalt mixtures is very common among transportation agencies. With the recent development of balanced mix design methods, it is becoming more important to understand how to optimize mixture performance by offsetting the adverse effects of RAM. In this paper, mixtures from three different sources were adjusted according to the availability adjusted mix design (AAMD) and corrected optimum asphalt content (COAC) methods. Three control mixtures containing RAM, three mixtures containing no RAM, five mixtures designed according to the AAMD method (two of which had 50% reclaimed asphalt pavement content), and two mixtures adjusted using the COAC-based approach were evaluated. Both asphalt mixture performance tester experiments and index tests were used in this study to evaluate material-level indicators of cracking and rutting resistance. Additionally, pavement performance simulations were carried out using AASHTOWare Pavement ME and FlexPAVETM to assess how the observed material-level differences led to differences in structural-level pavement performance. Both the AAMD and COAC methods improved cracking measures. However, the results suggest that the additional virgin binder added through the COAC method without any adjustments to the aggregate structure can have negative consequences for the rutting performance measures. In addition, the mixture and pavement performance results suggest that the AAMD method is a rational approach for including recycled binder availability in mix design procedures to promote improvements in the cracking performance of mixtures by controlling the volumetric properties and the aggregate structure of the mix without having a detrimental effect on rutting resistance.

Performance Comparison of Conventional and Biopolymer-modified Asphalt Mixtures for Airport Pavement

Raising the temperature of airport pavement softens its surface, leading to rutting or thermal cracking. As aircraft manufacturers lean toward heavier planes with higher tire pressures, challenges arise. To tackle these problems, incorporating polymers like high-density polyethylene into asphalt binders has emerged as a solution. This study investigates biopolymer-modified asphalt, blending conventional asphalt with highdensity polyethylene and pine resin. This study aims to compare the performance of asphalt mixtures using both conventional and biopolymer-modified asphalt binders. Various tests‒physical, Fourier transform infrared, energy dispersive X-ray, dynamic shear rheometer, volumetric properties, Marshall stability, retained stability, indirect tensile strength and Cantabro loss-were conducted. The results highlighted that integrating pine resin and high-density polyethylene increased the performance grade (PG) of the conventional asphalt from PG 64 to PG 82. Asphalt mixtures using biopolymer-modified binders exhibited superior stability, stiffness and resistance to moisture damage compared to those with conventional asphalt. These properties aligned with the specifications outlined in Item P-401 of the Federal Aviation Administration Advisory Circular 150/5370-10H. Keywords: Pine resin, High-density polyethylene, Biopolymer-modified asphalt, Performance grade 64, Performance grade 82

Study on the influence mechanism of hydrophobic materials-MPTMS and DMDMOS on the water resistance performance of asphalt mixtures

The interfacial adhesion between aggregate and asphalt is a critical factor affecting the water damage resistance performance of asphalt mixtures. To enhance the adhesion between aggregate and asphalt, Methyltrimethoxysilane (MPTMS) and Dimethyldimethoxysilane (DMDMOS) were co-opted to modify the aggregate surface. The interfacial strength between aggregate and asphalt was analyzed by water boiling test and contact angle experiment, and the mechanism of aggregate interfacial modification was investigated by combining SEM, FTIR and MD. The results showed that: hydrophobic treatment of aggregates reduces the water absorption rate of aggregates in a wet environment and significantly improves the water damage resistance of asphalt mixtures; MPTMS and DMDMOS reduced the aggregate surface polarity component, thus improving the match between aggregate and asphalt; The optimal processing environment for aggregates is acidity and 30 minutes. Further mechanistic tests and simulations showed that the reactive Si-O portion of the polymer reacts with the Si-O-C portion of MPTMS and DMDMOS to form hydrophobic clusters on the surface of the polymer, increasing the aggregate surface roughness. The clusters attract asphalt molecules to arrange closely and orderly around them. The intramolecular interactions and molecular angular energy of asphalt molecules are significantly reduced, which improves the stability of the aggregate-asphalt system, and further enhances the bonding energy between the aggregate and the asphalt, thus improving the water damage resistance of asphalt mixtures.

Evaluation of Cracking Resistance of SMA-13 Hot Recycling Asphalt Mixtures Reinforced by Basalt Fiber.

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, Wd/Ws) and 74.8% (flexibility index, FI), respectively. And the corresponding cracking resistance of hot in-place recycled mixture increased by 105.4% (Wd/Ws) 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.

The Impacts of Red Mud on Road Performance and Aging Resistance of Asphalt Mixture

The Impacts of Red Mud on Road Performance and Aging Resistance of Asphalt Mixture

Influence of Non-Melting Waste Plastics on Volumetric Properties and Performance of Asphalt Mixtures

The main objective of the study is to evaluate the impact of using polystyrene (PS) and polyethylene terephthalate (PET) plastics as an additive in asphalt mixtures. For this purpose, volumetric modification, moisture susceptibility along with performance variation at high, intermediate, and low temperature conditions were evaluated. Initially plastics were subjected to calorimeter analysis for assessing their melting characterization. Both PS and PET are included as dry mix additives individually at dosage levels of 3%, 6%, and 9% by weight of asphalt binder. Further, the changes in thermal properties of plastics occurring during mixture preparation were correlated to better understand the volumetric modification. PS, owing to its glass transition and partial amorphous nature, exhibited minimum deviation (<1%) from design air voids (4 ± 0.5%). PET was observed to increase the volumes of voids in mineral aggregate (VMA) and air void, owing to its crystalline nature. As regards performance, PS and PET modification enhanced the moisture resistance by 1.05 to 1.11 times the control mixture. The rutting tolerance index ( RTindex) value increased for all plastic modified mixtures from the indirect tensile asphalt rutting test (IDEAL RT) performed at 58°C. However, the intermediate temperature cracking tolerance index ( CTindex) at 19°C conveyed the high embrittled nature from plastic modification making the mixtures more susceptible to cracking. From the Gf versus l75 /m75 interaction diagram, it was conveyed that although addition of plastics improves the fracture toughness of asphalt mixtures, the ductile nature of mixtures is compromised. Also, PS and PET modification could not improve the ability of asphalt mixtures to resist thermal cracking, evaluated at −18°C.