Properties Of Asphalt Mixtures Research Articles

Effect of nanowollastonite wastes on bitumen and asphalt mixtures performance

Wollastonite is a neutral mineral with a high modulus of elasticity that is composed of lime and silica in almost equal proportions, and the structure of this mineral is fibrous and needle shaped, which distinguishes it from other minerals. In recent years, extensive research has been conducted on nanomaterials as bitumen modifiers and asphalt mixtures. The effect of morphology and nanoscale waste mineral wollastonite as a bitumen additive on the properties of asphalt mixture was investigated. According to the test findings, the use of nanowollastonite increases the G* sin δ parameter between 2000 and 3700 kPa at room temperature, resulting in a 45% reduction in the fatigue failure factor. Additionally, the rutting factor, G*/sin δ, increases between 3.75 and 4.75 kPa, indicating that the presence of nanowollastonite extends the pavement rutting life by 20% at an optimal concentration of 4% nanowollastonite. The findings demonstrate that waste nanowollastonite can be introduced as a new waste material to enhance the performance of asphalt pavement, considering the shape and size of its nanocomponents. Furthermore, incorporating waste nanowollastonite in the present design of asphalt concrete has a significant impact on reducing energy usage. Encouraging the use of these waste nanoparticles is worthwhile to reduce global energy consumption and pollution.

Enhancement Mechanism of Asphalt Mixture Skeleton Structures Due to Morphological Characteristics of Steel Slag

Uncertainty still exists about the enhancement mechanism of the skeleton structure brought about by the steel slag, and the relationship between skeleton structure of steel slag asphalt mixture and the mechanical properties is still ambiguous. This study quantified the skeleton structure of steel slag asphalt mixture and explored the enhancement mechanism of skeleton structure brought about by the steel slag. The relationship between skeleton parameters and mechanical properties of steel slag asphalt mixture was also established. The results show that recycling steel slag as aggregate improves the skeleton quality of mix. The slag particles are not susceptible to be oriented tending to the horizontal direction. The abundant angularity of steel slag increased the contact number while the rough texture and non-spherical shape of steel slag enhanced the contact length. This project provided new insight and a notable opportunity to advance the comprehension of the skeleton structure of asphalt mixture containing steel slag.

Environmental benefits of microwave-assisted self-healing technology for pavements - A Life Cycle Assessment comparative study

The maintenance and rehabilitation of roads is becoming a key challenge in the pavement industry to decrease the consumption of natural resources. Microwave-assisted self-healing technology extends the life-service of asphalt pavements for roads reducing the need for fossil fuels over its lifespan and saving the use of natural resources. This technique takes advantage of the thermoplastic and dielectric properties of asphalt mixtures that allows cracks to be closed, hence, heal and restore the asphalt mixtures mechanical behaviour without implementing more invasive traditional maintenance operations like milling and replacing the pavement. A Life-Cycle Assessment was carried out to determine the potential environmental benefits of using this technology quantifying its potential environmental impacts. Different scenarios in which the heating energy and the addition of slag varies has been evaluated and compared with a conventional road. Results shows that this technology could decrease a significant number of environmental impacts over the lifecycle.

Recycling the electric arc furnace waste after geopolymerization in bitumen: experimental analyses and LCA study

The conversion of solid waste materials into cleaner products for road paving. applications appears to be a promising and sustainable option. However, there is still a lack of attention given to quantifying the potential environmental benefits of recycling solid wastes in asphalt pavements, regarding the impact on asphalt performance. To address this gap, the present study investigates the effects of recycling electric arc waste based geopolymers on asphalt binder and mixture characteristics, as well as environmental outputs. For this purpose, geopolymers were incorporated into both neat and SBS-modified binders. A comprehensive rheological investigation was conducted using cutting-edge multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) analyses. Stability, Marshall quotient, and flow values, as well as dry and wetconditioned tensile strength were considered, to determine asphalt mixture properties. In the Life Cycle Assessment (LCA), greenhouse gases resulting from fuel and energy consumption in each inventory phase were determined. The varying service lifetimes, maintenance and rehabilitation plans, and production and construction requirements of the different asphalt schemes were taken into account. Subsequently, the environmental impacts of the asphalt mixtures, including global warming potential, acidification, eutrophication, and smog formation potential, along with the total energy demand, were calculated across different stages of the LCA. The results show that the geopolymerization process results in important contributions in terms of both environmental savings and pavement performance.

A model predicting mechanical properties of asphalt mixtures considering void ratio and loading conditions

The void ratio is an essential parameter in asphalt mixture design, which significantly affects asphalt mixtures' mechanical properties and road performance. The prediction model for mechanical properties will be established based on the Computed tomography (CT) scanning, strength, and fatigue test results in this research to reveal the relationship between the asphalt mixtures' mechanical properties and void ratio. Firstly, the voids' transverse and longitudinal distribution characteristics in asphalt mixtures of different gradations were investigated based on CT scanning. Then, the influences of void ratio, loading rates on the strength, and the impacts of void ratio and stress levels on the fatigue life were investigated by conducting indirect tensile tests. Finally, the mechanical properties prediction model was established for void ratio and loading conditions. Further, the feasibility of the model is verified in conjunction with existing research results. The results show that the void ratio calculated based on CT scanning is about 1.15 times the measured void ratio in the water weight method. The number of voids was uniformly distributed in the range of 15 mm∼50 mm in height and 10 mm∼40 mm in radius of the specimen. The asphalt mixtures' strength decreases with increasing void ratio and increases with increasing loading rate. The asphalt mixtures' fatigue life declines with increasing void ratio and stress level. The correlation coefficients of the established strength and fatigue prediction models were 0.963 and 0.976, respectively. The relative error between the measured strength, fatigue life, and predicted results is about 10.75% and 11.27%, respectively. This research provides a basis for designing high-performance asphalt mixtures by establishing the relationship between asphalt mixtures' microscopic and mechanical characteristics.

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.

Study on Multiple Effects of Self-Healing Properties and Thermal Characteristics of Asphalt Pavement

Asphalt pavements are prone to cracking in low-temperature environments, and microwave heating (MH) can heal the cracks effectively. This research mainly investigates the different MH effects on the self-healing properties of asphalt mixtures. With this objective, the three-point splitting test is conducted to generate the cracks. A microwave oven is employed to heat the samples, and a thermal camera measures the surface temperature. Results indicate that heating power and time show a positive linear correlation with healing efficiency, and the HI of the samples can reach over 80%. The HI of the samples decreases with the heating cycle, but the sample with reasonable power and time still has a HI higher than 70% after 5 cycles. The temperature peaks on thermal images indicate that uneven heating exists during heating, but the heating uniformity is within an acceptable range. The healing efficiency level (HEL) suggests that asphalt mixtures have very low inefficient healing behavior if the heating time is below 45 s, but HEL can reach 86.14% at 700 W after 60 s. Furthermore, although the HI of strength shows ideal results, the recovery of other crack parameters, including stiffness, fracture energy, flexible index, and crack resistance index, are not satisfactory.

Study of fractional Burgers damage creep model and creep properties of asphalt mixtures

Study of fractional Burgers damage creep model and creep properties of asphalt mixtures

Characterization of rutting damage based on two-dimensional image analysis of changes in mesoscopic aggregate properties of asphalt mixtures

Accurately predicting the rutting development law of asphalt pavement is of great significance for preventing and controlling pavement diseases. The aggregate skeleton of the asphalt mixture is the main load-bearing part and plays an important role in its anti-rutting performance. However, quantitative and mesoscopic evaluation indicators and standards for aggregate skeletons have not been established. This study aims to reveal the relationship between the mesostructured characteristics of asphalt mixtures and rutting damage. This paper uses two-dimensional image technology to analyze the dynamic change process of internal skeleton information of two graded asphalt mixtures under cyclic wheel load. According to the fractal theory, the fractal dimension and multifractal spectrum of the full-depth aggregate were calculated. The results indicate that the linear regression model between the mesoscopic skeleton information of asphalt mixture and the average rutting depth during the rutting test can be used to quantify the rutting performance. There is an obvious correlation between the fractal dimension of the section aggregate and the loading times, and there is a certain linear relationship between the multifractal spectrum indexes and the loading times. It indicates that the fractal theory index of aggregate can reflect the change of the macro performance of loading times.

Algorithms to create realistic virtual asphalt mixtures

This paper presents a set of algorithms for creating realistic three-dimensional (3D) models of asphalt mixtures based on its composition. The process begins by measuring the shape of the aggregates in the asphalt mixture. Using these measurements, an algorithm creates 3D volumes that approximate the size and shape of the aggregates. These volumes are then added to a virtual mixer in the same proportions as the aggregates in the real mixture and are pressed together until the air void content of the 3D model matches that of the real asphalt. This results in realistic models of aggregate skeletons in the asphalt mixture. Next, sections are taken from the aggregate skeletons and a mortar mixture, made up of bitumen, filler and fine aggregates, is applied to the sections. Geometrical rules are used to determine which areas of the sections are covered in mortar and which are air voids. The validation of virtual aggregates and air voids has demonstrated good correlations with actual ones. The resulting models are highly realistic and can be used to predict the mechanical or physical properties of asphalt mixtures in future studies.

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.

Study on the influence of coarse aggregate morphology on the meso-mechanical properties of asphalt mixtures using discrete element method

To investigate the influence of coarse aggregate morphologies on the performance of asphalt mixture, three discrete element models with different coarse aggregate morphologies were proposed in this study. Skeleton contact characteristics, skeleton contact stress, coarse aggregate movement characteristics, interfacial stress distribution, and micro-crack development characteristics with different coarse aggregate morphologies were compared and analyzed. The results indicate that there is often 40%–50% of compressive stress at the coarse aggregate contact point, 10%–20% of tensile stress, and 30%–40% of tensile and compressive mixed stress. Aggregate morphology has a more significant impact on the contact area than it does on the type of stress at the contact point or the number of main skeleton contact points. Contact stress, coarse aggregate movement, and crack development in the asphalt mixture are all greatly influenced by coarse aggregate morphologies. More needle-flake aggregates result in less contact stress, more coarse aggregate movement displacement, and faster asphalt mixture cracking. Shear stress makes up the majority of the micro-cracks that are caused by induced stress in asphalt mixture; tensile stress micro-cracks are quite minor, making up around 10% of the total number of micro-cracks. In order to increase the aggregate–asphalt interface qualities and the crack resistance of the asphalt mixture, it is important to avoid using too much needle-flake coarse aggregate. The findings can provide guidance for the choice of raw materials and mix ratios for asphalt pavement design, improving the asphalt mixture's meso-mechanics and macroscopic road performance.

Study on the effect of self-melting snow materials on the properties of asphalt mixture

Adding self-melting snow material to asphalt pavement can improve driving safety in winter weather. Self-melting materials can melt the snow on the road surface, without too much negative impact on asphalt pavement. Two commonly used self-melting snow materials are particle type and powder type. Through indoor experiments, the effects of two self-melting snow materials on the high-temperature performance, low-temperature performance, water stability, and anti-stripping performance of asphalt mixtures are compared. The experiment shows that these self-melting snow materials have little effect on the high-temperature and low-temperature performance of the asphalt mixture, and the low-temperature performance of the mixture decreased after freeze-thaw environment. After freeze-thaw cycle or immersion, the snow melt components in the mixture gradually precipitate, leading to the water stability and anti-spalling performance.

Evaluation of Asphalt Binder and Mixture Properties Utilizing Fish Scale Powder as a Biomodifier

Fish represent an abundant and underutilized waste product from the fishing industry. This study investigated the effects of incorporating fish scale powder (FSP) at various dosages (3%, 6%, 9%, and 12%) on the properties of asphalt binder and mixtures. Conventional tests, viscosity, storage stability, Fourier transform infrared spectroscopy, and multiple stress creep recovery tests were conducted on the binder. Mix design, wheel tracking, indirect tensile strength, fatigue, and ultrasonic pulse velocity tests were evaluated for the asphalt mixtures. The results showed that FSP increased binder stiffness and reduced temperature susceptibility but compromised low-temperature performance and workability regardless of dose. The storage stability test results showed improved high-temperature storage stability. In the mixtures, the permanent deformation resistance increased with increasing FSP content, decreasing the rut depth from 4.3mm for the control to 2.9mm at 12% FSP. The moisture damage resistance, indicated by the tensile strength ratio, increased from 90% for the control to 94.1% at 12% FSP. However, the fatigue life decreased from 14,010 cycles for the control sample to 11,190 cycles at 12% FSP. The dynamic and elastic modulus values before conditioning increased with higher FSP dosages, and this increasing trend was also observed after conditioning, signifying greater stiffness retention and moisture resistance of the asphalt mixtures containing higher amounts of FSP. Numerically, the 6-9% FSP range offered the optimum balance, enhancing the rutting resistance by 18% and moisture resistance by 3.2% compared to those of the control, while limiting the fatigue life to 12% and maintaining the workability. Overall, fish scale powder has potential for use as an asphalt biomodifier by transforming an environmental liability into a value-added sustainable paving material.

Multi-scale measurement of constitutive viscoelastic properties of bituminous composites considering moisture and deicing conditions

The use of salt and chemical deicers can cause significant damage to road infrastructures. This study investigates the impact of different deicers on the viscoelastic properties of mastic and asphalt mixtures, with a focus on characterizing their behavior at varying temperatures and loading frequencies. The samples were subjected to conditioning in solutions of distilled water, salt, Calcium Magnesium Acetate (CMA), and Potassium Acetate (KAc) at 60°C for 96hours, followed by frequency sweep and dynamic modulus tests at different temperatures and loading frequencies. The results indicate that moisture conditioning with distilled water softens asphalt mixtures and mastic at low loading frequencies, while brine softens the former at low temperatures. Salt's high interaction with mixture aggregates cannot be ignored. CMA's effect on the fatigue behavior of mastic samples is highly dependent on loading frequency, while KAc increases stiffness at intermediate and high temperatures. All the deicers reduce resistance to rutting damage, with CMA having the most negative effect. Both the 2S2P1D and the generalized Maxwell model can well (R2≥0.90, Se/Sy≤0.35) predict the viscoelastic properties of dry asphalt mixture. However, in the presence of distilled water and the deicers, asphalt mixture viscoelastic properties cannot be predicted according to asphalt mastic characteristics by implementing the homothety method which indicates different effects of distilled water and the deicers on various scales of bituminous composites.

Structure evolution analysis of asphalt mixtures during compaction based on particle tracking and granular properties

Pavement compaction is a process of structure evolution of materials accompanied by energy dissipation, which is closely related to the inherent granular properties of asphalt mixture. This research achieved dynamic characterization of particle migration energy and contact force development through particle tracking technique and discrete element simulation. Analytical theories for multi-stage structure evolution and compaction mechanisms were proposed based on granular properties. Results indicate that kinetic, dissipative, and potential energies dynamically represent stages of structure evolution, determined by particle collisions, self-organization into arches, and interlocking reinforcement. The initial density state is established after interparticle collisions, while self-organization occurs as particles adaptively rearrange spatially by rotation in response to unbalanced forces, accompanied by a cyclical strengthening trend of arch formation and collapse. Arches facilitate stress redistribution toward isotropy, with strong contact forces exhibiting a top-down and side-center trend, progressively supported by particles larger than 4.75 mm. Theoretical measures for compaction control were proposed, including pre-calculation of IC, selection of compaction temperature corresponding to the optimum energy efficiency, and control of principal stress deflection within the friction cone. This research aims to provide insight into granular properties and compaction dynamics, thereby contributing to intelligent compaction.

Effects of utilization of rejuvenator in asphalt mixtures containing recycled asphalt pavement at high ratios

This study investigated the properties of asphalt mixtures, including recycled asphalt pavement, at high ratios. In addition, to improve the properties of asphalt mixtures containing recycled asphalt pavement, bitumen was modified with a rejuvenator at proportions of 2, 4, and 6% and used together with 35, 40, and 45% recycled asphalt pavement. Based on test results, the strength of asphalt mixtures increased as the ratio of recycled asphalt pavement added to asphalt mixtures increased. In addition, all combinations of recycled asphalt pavement and rejuvenator agent had higher indirect tensile strength values according to the reference mixture. The rutting resistance of asphalt mixtures increased as the ratio of recycled asphalt pavement added to the asphalt mixtures increased. Asphalt mixtures containing 45% recycled asphalt pavement and 2% rejuvenator-modified bitumen showed the best rutting resistance. The significance of the obtained results was determined with appropriate statistical analysis. So, it has been determined that the rejuvenator used in this study can effectively improve the properties of asphalt mixtures containing recycled asphalt pavement. Finally, the rejuvenator agent used in this study allowed the utilization of recycled asphalt at a higher ratio than the amount specified in the Highway Technical Specification.

Characterization on the mesostructural properties of asphalt mixtures based on meso-element equivalence method

The randomness and variation of material composition at the meso-scale lead to some limitations in the application of asphalt mixture. When all features are taken into account, the computational effort increases significantly. Therefore, the relationship can be established using the meso-element equivalence method (MEEM). In this paper, the effects of aggregate-asphalt interface, initial void defects and material damage were introduced and MEEM of asphalt mixture was established based on industrial computed tomography (ICT) and finite element method (FEM). The rationality of the model was verified by laboratory performance tests, and the effects of aggregate type, mixture gradation and mesostructural parameters on the mechanical response of MEEM were compared and analyzed. The results showed that the MEEM model captures the mechanical behavior of asphalt mixtures well, the input of visco-elastic material parameters is an important step of MEEM simulation accuracy. The aggregate type, the discrete degree of the skeleton structure and the distribution characteristics of mesostructural parameters are important factors affecting the mechanical properties of asphalt mixture in MEEM.

A Study of the Bond Strength and Mechanism between Basalt Fibers and Asphalt Binders

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.

Causes of Asphalt Pavement Blistering: A Review

No theoretical model effectively explains the blistering process, which provokes functional distress in asphalt pavements worldwide. This study focuses on the possible causes of blistering, the physical processes that drive blistering, the role of asphalt properties, and the uncertainties and gaps in the current knowledge. This paper analyzes peer-reviewed studies on pavement blistering published between 1959 and 2022 retrieved in a systematic literature review to justify and model this distress observed on sidewalks, airports, and bridges. According to the scientific literature, high surface temperatures due to solar radiation are the common factor responsible for uplifting, but several causal mechanisms have been investigated. Indeed, chemical reactions, evolutionary materials, thermal buckling, and physical reactions are the generally recognized causes. Their effects on pavement smoothness vary according to the various interdependent geometrical, physical, and mechanical properties of asphalt mixtures and the boundary conditions. Both the mix design and construction processes can hinder the blistering process that occurs during daytime hours of the hot season, right after the work is finished or a few years later. Further research should identify measures to prevent bulges whose management after uplift is difficult but necessary to avoid safety and functional issues.