Properties Of Asphalt Mastics Research Articles

Study on the Effect of Fibers on the Properties of Asphalt Mastics

To study the influence of fiber on the properties of asphalt mortar, the properties of lignin fiber, polyester fiber, and basalt fiber were summarized and analyzed respectively. The high- and low-temperature properties of fiber asphalt mortar were studied and analyzed by using three indexes, rutting factor and tensile fracture energy. The results showed that all three kinds of fibers could improve the performance of asphalt mortar to varying degrees, with lignin fiber demonstrating the best effect, followed by basalt fiber and polyester fiber. The type the fiber can be selected based on the required thermal stability and cost depending on the project type.

Determination of optimum limestone filler content in asphalt mastic by dielectric spectroscopy

The rheological and dielectric characteristics of asphalt mastics with different ratios of limestone filler were analyzed and compared with each other for road pavement applications. The dielectric properties of asphalt mastics are studied as a function of frequency (0,1–106 Hz) at different temperatures ((-)40°C−40°C). The glass transition temperature and the relaxation behaviour were determined by Vogel–Fulcher-Tamman and Cole–Cole equations, respectively. The free volume fraction was calculated by the Dolittle equation. The filler ratio dependence of the dielectric properties was attributed to the variation of the void fraction. This result was related to the glass transition temperature and ductility. The sample with 6 wt% limestone filler showed the highest dielectric constant value among all samples for all temperatures due to the excellent adhesion between binder and filler. Consequently, it was determined to be the optimum value to design hot mix asphalt for use in territories with high-temperature differences.

Exploring the Utilization of PHC Pile Waste Concrete as Filler in Asphalt Mastics.

Using solid waste to replace limestone filler in asphalt concrete can not only reduce the cost of road construction, but also improve the utilization rate of solid waste. In this study, PHC pile waste concrete (PPWC) was innovatively used to replace limestone filler in asphalt mixture and its effect on the physical and rheological properties of asphalt mastics was studied. Firstly, PPWC was ground into filler particles with a diameter less than 0.075 mm. The physical properties, particle characteristics and chemical composition of PPWC filler and limestone filler were compared. Asphalt mastics were prepared with different filler-asphalt volume ratios (20%, 30% and 40%) and the physical properties, high-temperature rheological properties and low-temperature cracking resistance of asphalt mastics were tested. The experimental results showed that the surface of PPWC filler is rougher and has lower density and smaller particle size than limestone filler. When the filler content is the same, PPWC filler asphalt mastics have lower penetration and ductility, higher softening point than limestone filler asphalt mastics, and the viscosity of PPWC filler asphalt mastics is more sensitive than limestone filler asphalt mastics. PPWC filler asphalt mastics demonstrated superior high-temperature stability, but poorer low-temperature cracking resistance compared to limestone filler asphalt mastics. In conclusion, PPWC fillers can be used to replace limestone fillers in asphalt mixtures. The finding of this study will provide a new solution for the construction of eco-friendly roads.

Effect of Basalt Fiber Diameter on the Properties of Asphalt Mastic and Asphalt Mixture.

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.

Study on the Rheological Properties of Fly Ash Modified Asphalt Mastics

Fly ash is one of the industrial waste residues with significant emissions in China, and its rational utilization has important economic significance and environmental value. Due to the similarity in properties between fly ash and limestone mineral powder, it is possible to replace the mineral powder filler in asphalt concrete with fly ash. This article explored the feasibility of replacing the mineral powder with fly ash in an asphalt mixture through the study of fly-ash-modified asphalt mastic. Firstly, the microstructures and elemental compositions of fly ash and mineral powder were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. Then, the rheological properties of asphalt mastics with different fillers were studied using dynamic shear rheological (DSR) tests. The results show that when the stress level was 3.2 kPa, the change in the Jnr value was different from that at 0.1 kPa, indicating that after increasing the stress level, the Jnr of fly ash asphalt mastic was smaller, and fly ash can improve the high-temperature creep performance of asphalt mastic. Replacing mineral powder with fly ash can improve the high-temperature rheological properties of asphalt mastic, but this damages the elastic and crack resistance properties of the asphalt mastic. In practical applications, partial substitution of mineral powder can be considered for the preparation of an asphalt mixture.

Study on Thixotropic Properties of Asphalt Mastics Based on Energy Viewpoint

An asphalt mastic has thixotropic characteristics that significantly influence its fatigue and healing performance. Therefore, understanding the thixotropy of an asphalt mastic is clearly of great importance. However, research in this area is still in the early stages. This study focuses on self-heating as one of the biasing performances of asphalt material by analyzing the viscosity, stress, and hysteresis loops the of asphalt mastics under cyclic shear loading. Twelve types of asphalt mastics fabricated with asphalt, as well as different types of mineral filler, were selected to examine thixotropy. In addition, the filler/asphalt ratio was examined via the hysteresis technique to analyze the hysteresis loop and the viscosity–shear rate. The thixotropic potential function was also studied from the energy viewpoint. The results show that asphalt mastics with different asphalt binders, mineral fillers, and filler volume fractions showed hysteresis loops for shear stress versus shear rate diagrams. With an increase in the loading times of the cyclic load, the area of the hysteresis loop gradually decreases, and the hysteresis area most likely features a relatively stable value. The thixotropy of the asphalt can be significantly reduced by adding filler, and different types of mineral filler can slightly influence the thixotropy. The viscosity decreases with an increase in the shear rate, and it gradually recovers with a decrease in the shear rate. The greater the filler/asphalt ratio, the greater the viscosity, and the faster the viscosity’s descent is with the prolongation of time. Due to the existence of a higher amount of filler content, the recovery of a viscosity crack is more difficult. For asphalt mastics with high filler/asphalt ratios, the thixotropic mechanism can be explained via particle agglomeration and the depolymerization theory. For asphalt mastics with low and medium filler/asphalt ratios, the thixotropic mechanism can be explained via the particle chain theory. The damage and recovery of the internal structure of an asphalt mastic can be characterized by the structural failure potential function and the structural recovery potential function, respectively.

Influence of Filler Type and Rheological Properties of Asphalt Mastic on the Asphalt Mastic-Aggregate Interaction.

The asphalt mastic-aggregate interaction plays an important role in the overall properties of asphalt mixtures and their durability in service in flexible pavements. This paper aims to study the influence of the physico-chemical features of fillers and the rheological properties of asphalt mastics on the bonding behavior between asphalt and aggregate, and the interfacial deterioration mechanism when subjected to static water immersion and pressured water immersion. It was found that the filler type (limestone powder, basalt powder, and granite powder) had a certain influence on the complex modulus of asphalt mastics, and its pore volume and specific surface area had significant effects on the phase angles and permeability of asphalt mastics. The effect of water pressure can accelerate the deterioration of bond strength of the asphalt mastic-aggregate interface in the short term, indicating that the dynamic water pressure generated by the driving load promotes the water damage process in asphalt pavements. In comparison, the residual bond strength ratio of the granite-asphalt mastic aggregate was the highest, while its bond strength was lower than that of the interface between limestone-asphalt mastics and limestone aggregate. This demonstrated that a low asphalt mastic complex modulus and a high phase angle are helpful in improving the durability of asphalt mixtures subjected to static and pressured water immersion conditions.

Creep and fatigue properties of asphalt mastic with steel slag powder filler

Steel slag powder (SSP) was selected as an inorganic micro powder filler instead of limestone powder (LSP) to prepare asphalt mastic in this paper. Firstly, the microscopic characteristics of SSP and LSP such as particle size distribution, surface morphology, phase composition and chemical composition were characterized by laser particle size analyzer, scanning electron microscopy (SEM), X-ray diffraction (XRD) analyzer, and X-ray fluorescence (XRF) analyzer. Then, the composition and content of chemical functional groups of asphalt mastics were studied by fourier transform infrared spectrometer (FTIR). Finally, the effect of SSP on the creep and fatigue properties of asphalt mastics was investigated via multiple stress creep recovery (MSCR) and time scanning experiments using a dynamic shear rheometer (DSR). The results showed that the addition of SSP as mineral filler instead of LSP to asphalt binder enhanced the deformation resistance and the fatigue life of the asphalt mastics.The complex shear modulus of asphalt mastics show an increase trend with an increase in the SSP content. Compared with LSP asphalt mastic, the complex shear modulus of SSP asphalt mastic ( SSP content 30 %, 50 %, 100 %) increased by 84.9 %, 118.0 % and 256.1 %, respectively. From the perspective of structural design and material selection, the fatigue life NDER corresponding to the cumulative dissipative energy rate(DER) is recommended to analyze the fatigue life of asphalt mastics.The results of the MSCR and time scanning experiments demonstrated that the use of a combination of SSP and LSP as filler could be an effective approach for comprehensive utilization of steel slag in asphalt mixture.

Utilization of calcium carbide slag as alternative filler in asphalt mastic: Filler characteristics, rheological and adhesion properties

Calcium carbide slag (CCS), a solid waste generated from a production process of acetylene gas, is considerably growing every year. It is necessary to expand application scope of CCS to improve its consumption. Feasibility of CCS as a substitute for natural limestone (NL) fillers and asphalt mastic properties was studied in this work. Properties of CCS powder and NL powder were characterized by laser particle size analyzer, scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), and acid-base analyses. Asphalt mastic characteristics were evaluated using a viscosity test, rheological test, and adhesion test. The results show that CCS has a greater particle size than NL, yet the CCS surface is rougher, which can facilitate its bonding with asphalt. In addition, high relative intensity of calcium in CCS provides excellent conditions for application as filler. Viscosity, complex modulus (|G*|), rutting factor (|G*|/sin δ), recovery percentage (R), and bonding strength can be enhanced with an increase in CCS content. While phase angle (δ) and non-recoverable creep compliance (Jnr) decrease, indicating CCS enhanced the stiffness and elastic behavior of asphalt mastic. CCS can improve rheological properties of asphalt mastic and mastic-aggregate interface adhesion, decrease moisture sensitivity and costs of asphalt mixtures. Therefore, CCS has promising applications in asphalt pavement engineering as a substitute for NL, which contributes to environmental protection.

Dielectric properties of asphalt mastics considering temperature effect

Ground Penetrating Radar (GPR) evaluates the quality of asphalt pavements and identifies different distresses based on the difference in the dielectric properties of asphalt pavement materials at different positions of the asphalt pavement structural layers. Asphalt mastic is an important component of asphalt mixture, and the performance of the mortar considerably affects the macro dielectric properties of the mixture. Hence, investigating the dielectric properties of asphalt mastic is crucial in understanding the overall dielectric properties of asphalt mixture. As a temperature-sensitive material, asphalt mastic exhibits temperature-dependent variations in its dielectric properties. Thus, this study conducted tests to investigate the dielectric properties of asphalt mastic at different temperatures and evaluated classical dielectric models. The results showed that the classical models did not adequately predict the dielectric properties of asphalt mastic because classical models ignore the effect of temperature on the dielectric properties of asphalt mastic. Micro test results show that temperature will affect the surface and internal structure of asphalt mastic, and then affect the performance of asphalt mixture.Through model verification, it is found that the model has a high calculation accuracy, which is more than 90%. This can quantify the influence of temperature field on the dielectric properties of asphalt mastic, and also pave the way for the next research on the temperature effect on the dielectric properties of asphalt mixture. This is because the proposed model not only considers the dielectric constant of asphalt mastic components, but also considers the influence of temperature on the dielectric constant of components. These research results not only have important academic value for enriching and developing the basic theory of GPR, but also can provide guidance for selecting the best filler-asphalt ratio in the actual field.

Influence of iron tailing filler on rheological behavior of asphalt mastic

• Limestone filler (LF) was substituted by iron tailing filler (ITF) in mastics under different f/b ratios. • The interaction between ITF and asphalt matrix was primarily physical. • ITF possessed a superior stiffening effect on mastics than LF. • A new index Δ T d was proposed to quantify the low-temperature performance of ITF mastics. • The substitution of ITF should be controlled within 1.0 f/b ratio. Iron tailings, one kind of widespread solid waste, were preliminarily regarded as a potential substitute for mineral filler in asphalt mixtures. However, the overall rheological properties of asphalt mastics incorporating iron tailing filler (ITF) and the effect mechanism of ITF remain unclear, which is detrimental to the generalized utilization of ITF in asphalt pavement. To fill this gap, the present study selected ITF and limestone filler (LF) to fabricate mastics with four filler/asphalt weight (f/b) ratios (0.6, 0.8, 1.0, 1.2). The blending mechanism and surface morphology of mastics were revealed by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The rotational viscosity test, dynamic shear rheometer test as well as bending beam rheometer test, were conducted to comprehensively study the rheological behavior of mastics. A new index Δ T d was proposed to quantify the influence of ITF on low-temperature cracking performance. Results show that the interaction between ITF and asphalt matrix is predominantly physical, and ITF possesses a smaller particle size which is beneficial to stiffening the mastics. However, the worse infiltration and distribution uniformity of ITF in mastics than that of LF may result in poorer adhesion. Regarding the rheological behavior, the substitution of ITF can highly improve the viscosity, complex modulus, and creep stiffness while slightly decrease the phase angle, viscosity-temperature susceptibility, and m -value of mastics, indicating a higher stiffness and elasticity of ITF mastics. Notably, the plateau region of phase angle may appear in ITF mastics with high filler concentration at low frequencies, representing a more significant elastic response. Besides that, Δ T d remains between −3.5 and −1.1 ℃. These results prove that the substitution of ITF is advantageous for the anti-rutting performance of asphalt pavement but may jeopardize its workability and low-temperature cracking resistance in particular with the excessive incorporation (f/b ratio > 1.0) of ITF.

Rheological Properties of Styrene-Butadiene-Styrene Asphalt Mastic Containing High Elastic Polymer and Snow Melting Salt.

Sprinkled snow melting salt (SMS) exerts a snow melting effect and also has a negative impact on the asphalt pavement and the environment. Salt storage pavement technology can alleviate these two problems. However, non-alkaline SMSs may have the risk of affecting asphalt mastic properties and further affecting the mechanical properties of asphalt pavements. Therefore, the general properties and rheological properties of two styrene-butadiene-styrene-modified asphalts with and without high elastic polymer were studied after adding SMS. The asphalt mastic without a high elastic agent is defined as the SBS group, and the other group is the HEA group. Our results show that the HEA group shows a lower penetration and a higher softening point, ductility, and viscosity than the SBS group. The more the SMS, the more the reduction effect of the general performance. The elastic recovery of asphalt mastic decreases with the content of SMS. SMS has no obvious effect on the ratio of the viscous and elastic composition of asphalt mastic. The creep of asphalt mastic increases with the content of SMS. The high elastic polymer can significantly reduce the creep, and even the strain of HEA100 is smaller than that of SBS00. SMS increases the creep stiffness and reduces the creep rate at low temperature. Although SMS increases the potential of asphalt pavement to melt ice and snow, it also reduces the high-temperature rutting resistance and low-temperature crack resistance of asphalt mastic. Salt storage pavement materials can be used in combination with high elastic polymers to reduce the negative effects brought by SMSs.

Predicting Dynamic Properties of Asphalt Mastic Considering Asphalt-Filler Interaction Based on 2S2P1D Model.

The relationship between the various phases of asphalt materials, from asphalt binder to mastic and mixture, has received great attention over the years, with efforts being made to establish linkages among these phases. Many methods for predicting the rheology properties of asphalt mastics from those of asphalt and filler volume fractions exist. However, most prediction methods are based on an empirical formula and on the micromechanical model. Very few research studies focus on the constitutive model. In addition, relatively little research has explored the influence of asphalt–filler interaction on mastic’s rheology properties, which is believed to be an important factor. In this study, the 2S2P1D (two springs, two parabolic elements, and one dashpot) model was applied to link the behavior of asphalt binder, filler volume fraction, asphalt–filler interaction and asphalt mastic. First, the interaction between asphalt and filler was evaluated, and the interaction parameter C of the Palierne model was used as an assessment indicator to calculate the effective filler volume fraction of asphalt mastic. Then, the relation between the 2S2P1D model parameters of asphalt mastic and those of asphalt binder and the effective filler volume fraction was analyzed. Finally, a simple relationship associating the 2S2P1D model parameters , of mastic and that of asphalt binder and the effective filler volume fraction was developed. The proposed expression was validated, and the result showed that it was an efficient model for the shear complex modulus prediction of virgin asphalt mastic.

Effect of Graphene Nanoplatelets (GNPs) on Fatigue Properties of Asphalt Mastics.

To investigate the effect of graphene on the fatigue properties of base asphalt mastics, graphene nanoplatelets (GNPs)-modified asphalt mastics and base asphalt mastics were prepared. A dynamic shear rheometer (DSR) was used to conduct the tests in the stress-controlled mode of a time-sweep test. The results showed that GNPs can improve the fatigue life of asphalt mastic. Under a stress of 0.15 MPa, the average fatigue life growth rate () was 17.7% at a filler-asphalt ratio of 0.8, 35.4% at 1.0, and 45.2% at 1.2; under a stress of 0.2 MPa, the average fatigue life growth rate () was 17.9% at a filler-asphalt ratio of 0.8, 25.6% at 1.0, and 38.2% at 1.2. The growth value (ΔT) of fatigue life of GNPs-modified asphalt mastics increased correspondingly with the increase of filler–asphalt ratio, the correlation coefficient R2 was greater than 0.95, and the growth amount showed a good linear relationship with the filler–asphalt ratio. In the range of 0.8~1.2 filler–asphalt ratio, the increase of mineral powder can improve the fatigue life of asphalt mastics, and there is a good linear correlation between filler–asphalt ratio and fatigue life. The anti-fatigue mechanism of GNPs lies in the interaction between GNPs and asphalt, as well as its own lubricity and thermal conductivity.

Verifying the Mechanical Performance of Cold and Hot Asphalt Mastics Containing Jet Grouting Waste as a Filler

In the road construction sector, the CO2 emissions that affect global warming are, in most cases, from the asphalt mixtures production activities that are carried out at high temperature (above 160 °C). The research here presented aims to investigate the physical-mechanical properties of asphalt mastics made up using jet grouting waste (JW) as a filler produced through both cold (40–50 °C) and hot mixing process. The first step focused primarily on examining the effects of optimal blending time and curing time of the mastics. The second step focused on the investigation of the rheological properties using a dynamic shear rheometer and carrying out a frequency sweep test at temperatures ranging from 0 to 50 °C with increments of 10 °C, and a multiple stress creep and recovery (MSCR) test under 0.1 and 3.2 kPa load levels at temperatures of 40 and 50 °C. Four cold asphalt mastic solutions were analyzed and then compared to three hot traditional ones, keeping constant, on the one hand, the binder weight and filler over binder weight ratio (0.5), and, on the other hand, changing the type and amount of filler. The compositions of the hot and cold asphalt mastics were as follows: (a) 33% limestone filler (LF) plus 67% bitumen (concerning the cold mixing process, the bitumen content refers to the amount of bitumen into the bitumen emulsion), (b) 33% JW plus 67% bitumen, (c) 16.5% LF plus 16.5% JW and 67% bitumen. The fourth solution designed only for cold asphalt mastic was made up of 33% Portland cement (PC) plus 67% bitumen (referring to the amount of bitumen in the bitumen emulsion). The main findings showed that the optimal performance was achieved at high test temperature by cold and hot asphalt mastics made up adding LF and JW filler, which showed a pronounced elastic behavior. Moreover, the cold asphalt mastic solution made up of LF and JW filler showed better performance than the mastic made up using PC, reaching over 40% increase of the shear modulus and 30% lower non-recoverable creep compliance values at all test temperatures.

Adhesive behavior and pavement performance of asphalt mixtures incorporating red mud as a filler substitute

With the massive exploitation and utilization of no-renewable natural resources, good-quality road building materials has been becoming scare and it is an urgent demand to explore and develop alternatives. This study investigated feasible approaches of using red mud as a filler substitute to replace limestone powder in asphalt mixtures. In order to elaborate its influence on adhesive behavior, surface energy components of various fillers, base bitumen, the powder-bitumen interface and the aggregate-asphalt mastic interfaces were calculated and characterized. The mechanical properties of asphalt mastics and asphalt mixtures were assessed by using Quality Control Test (QCT), Hamburg Wheel Tracking (HWT) test and Simple Performance Test (SPT). Referring to the thermodynamic theory, the adhesive performance of the red mud-bitumen interface can be improved by the addition of hydrated lime or Portland cement and the moisture resistance of the aggregate-asphalt mastic bond can be enhanced. It was found that incorporating the red mud can improve the stiffness and the elastic recovery of asphalt mastic, which in turn had a potential to improve the high-temperature performance of the corresponding asphalt mixtures. Regarding to pavement performance, replacing limestone powder by red mud improved the rutting resistance of asphalt mixtures and the moisture resistance can be enhanced by incorporating a certain amount of hydrated lime or Portland cement.

Interfacial bond strength and moisture induced damage characteristics of asphalt mastic-aggregate system composed of Nano hydrated lime filler

The present study was undertaken to investigate the impact of a unique combination of fillers on interfacial bond strength and moisture-induced damage potential of asphalt mastic. One asphalt binder (AC-30), three fillers including Basalt (B), Hydrated Lime (HL), and Nano-Hydrated lime (NHL) were selected to prepare asphalt mastics for a wide range of filler-binder (f/b) ratio (0.6 to 1.2). The dosages of HL and NHL were considered 0%, 5%, 10%, 15%, and 20% by weight of asphalt binder, and the dosage of B filler was adjusted to meet the respective f/b ratio. The interfacial bond strength and moisture-induced damage potential of asphalt mastic specimens were determined using the Bitumen Bond Strength (BBS) test. The BBS test parameters inferred that both B-HL and B-NHL filler combinations can enhance the bond strength and moisture damage resistance of asphalt mastic. Besides, asphalt mastic composed of B-NHL filler can be less susceptible to bond failure and moisture damage with improved adhesion and cohesion properties than B-HL filler. Additionally, asphalt mastic composed of a lower percentage (10%–15%) of NHL filler showed better bond strength and moisture damage resistance over mastic composed of a higher percentage (15%–20%) of HL filler. Asphalt mastic prepared with an f/b ratio less than 1.0 was found to be suitable to achieve better performance considering the moisture-induced damage properties. Grey relational analysis (GRA) method was used to analyze the correlation degree between filler properties and moisture damage properties of asphalt mastics. Based on the GRA results, Rigden voids and specific surface area are suggested to be the two most influential properties on the moisture-induced damage potential of asphalt mastic.

Effect of different fibers on the properties of asphalt mastics

Asphalt mastic is a key component affecting the performance of asphalt mixtures. Fibers can efficiently improve the performance of asphalt mastic. Four types of fibers, including two types of flocculent fibers (lignin fibers and sepiolite fibers) and two types of bundle fibers (basalt fibers and aramid fibers), were selected to study the effect of fiber morphology on the performance of asphalt mastic in this study. Firstly, the thermal stability, the asphalt absorption, and the microscopic morphology of various fibers were tested. Secondly, relevant performance tests, including penetration, softening point, bending beam rheometer test (BBR), and dynamic shear rheology test (DSR) test, were conducted on asphalt mastic samples prepared with various fibers. The results show that the flocculent and the bundle fibers played different roles in asphalt mastic. The flocculent fibers could stabilize asphalt, while the bundle fibers could enhance the toughness. The addition of fibers into asphalt mastic improved rutting resistance.

Assessing the effect of fillers on LVE properties of asphalt mastics at intermediate temperatures

This study aims at examining the performance of asphalt mastics in the Linear Viscoelastic (LVE) domain incorporating three Indian and three Austrian fillers. The various physical, morphological, and chemical properties of the fillers were analyzed with the help of respective characterization tests. In addition to the particle size distribution curve and fineness modulus, a new parameter called Filler Grain Coefficient (FGC) has been introduced in this study to quantify the distribution of particles in the system. This paper also attempts to find a correlation between various physical parameters. There are two variables i.e., $$\left| {G^{*} } \right|_{\text{LVE}}$$ and $$\left| {G^{*} } \right|_{\text{ratio}}$$ in order to quantify the Linear Viscoelastic complex modulus. The effects of both volume and surface area of fillers have been manifested by three ratios denoted as V/FM, V/FGC, and V/RV. To compare the outcome of the study, the Strategic Highway Research Program Linear Viscoelastic strain criteria is also included, which examines the applicability of the criteria to the asphalt mastics. The research incorporates a wide range of fillers with variable properties, as confirmed by the test results. Filler parameters Rigden Voids and Filler Grain Coefficient were found to be strongly correlated with almost all physical properties. On the grounds of variation in LVEM with volume concentration of filler, the highest rank can be attributed to Red Mud and LimeStone, respectively, followed by other fillers with Marble Dust being the lowest. The reinforcing effect of fillers and higher surface area contributed to the exponential increase in $$\left| {G^{*} } \right|_{\text{LVE}}$$ , with an increase in volumetric concentration. The variation of both variables: $$\left| {G^{*} } \right|_{\text{LVE}}$$ and $$\left| {G^{*} } \right|_{\text{ratio}}$$ , presented V/FM as the most worthy parameter, as it illustrated variation at different temperatures. The Linear Viscoelastic limits obtained from the study were relatively conservative compared to those from the SHRP study, this confirms the unsuitability of applying SHRP equations to the asphalt mastics. Moreover, the relationship instigated in the study can be used to reckon the LVE strain limit and to further analyse asphalt mastics.

Influences of ball-milled limestone particle sizes and shapes on asphalt mastic stress relaxation behavior

Asphalts often have filler particles added to improve their mechanical properties. Three distinct filler particle fractions were produced by a planetary high-energy ball mill from limestone aggregates (2.36–4.75 mm). Their particle sizes and shapes were studied by binary image processing and related to milling time and aperture size. The relaxation properties of asphalt mastics prepared with fillers of various sizes and shapes were investigated at a constant strain. Insights into the effects of particle size and shape on mastic relaxation behavior were gained by single regression analysis (SRA) in conjunction with grey relational analysis (GRA). The results show that particle size distributions had noticeable local differences in their slopes and spread, while particle shape distributions showed a narrow range of variability for the studied shape descriptors. Based on stress relaxation curves, fine particles were found to cause binders to become stressed more rapidly than coarse particles. Modified mastics showed much faster stress relaxation than corresponding base mastics at stage I, and exhibited higher stable stress levels than base mastics at stage II. A stress relaxation model was established and found to agree well with experimental data, indicating that mastic relaxation properties can be effectively modeled. Furthermore, the SRA coupled with GRA can provide a simple and effective approach to predicting the effects of particle size and shape on mastic relaxation behavior.