Road Performance Of Asphalt Mixture Research Articles

Investigation on the Performance of Modified Corn Stalk Fiber AC-13 Asphalt Mixture

As an agricultural waste, a large amount of corn stalk will cause environmental pollution. In order to realize the resource utilization of waste and meet the strict requirements of modern traffic on pavement strength and durability, it was modified and applied to an AC-13 asphalt mixture to study its influence on the road performance of asphalt mixture and its mechanism. The road performances of modified corn stalk fiber, lignin fiber, and ordinary asphalt mixtures were evaluated via the wheel tracking test, low-temperature bending test, water immersion Marshall test, freeze–thaw splitting test, and fatigue test. Based on the results of three-point bending fatigue test, the viscoelastic parameters and indexes of the fiber asphalt mixture were obtained by fitting the loading specimen and deflection data with the Burgers constitutive model, and the creep strain response was analyzed by applying dynamic load, so as to explore the relationship between the viscoelastic characteristics and creep behavior of modified corn stalk fiber and AC-13 mixture. The long-term high-temperature performance test of the asphalt mixture with the best fiber content was carried out by using the long-term pavement intelligent monitoring equipment independently developed by the group of investigators. According to the findings, the ideal fiber contents for modified corn and lignin in asphalt mixture are 0.2% and 0.3%, respectively. Among them, the modified corn stalk fiber with a 0.2% content has the best effect on road performance, viscoelastic performance, and the asphalt mixture’s creep behavior under dynamic load. Compared with the 0.3% lignin fiber asphalt mixture, its dynamic stability, bending stiffness modulus, immersion residual stability, freeze–thaw splitting strength ratio, and loading times at failure increased by 19.9%, 18.28%, 4.19%, 8.6%, and 9.15%, respectively. Compared with ordinary asphalt mixture, it increased by 47.0%, 28.72%, 7.65%, 15%, and 75.81%, respectively. Moreover, when modified corn stalk fiber is added at 0.2%, the viscoelastic delay time of asphalt mixture is the longest, the strain peak value and rut depth are at a minimum, and the viscoelastic properties, creep properties, and long-term high-temperature properties are the best.

Properties of waste vegetable oil recycled asphalt-binder: a molecular simulation study

ABSTRACT The aging of asphalt-binder during long-term use is an important reason for the decline in road performance of asphalt mixtures. In this study, waste vegetable oil (fried for 1-2h) was investigated as a rejuvenator of asphalt-binder. The optimisation effect of waste vegetable oil on the performance of asphalt-binder with different aging degrees (RTFOT, PAV15/20/48h) was evaluated by testing their conventional physical properties, high-temperature properties, and low-temperature properties. The molecular dynamics method was used to construct models, and the diffusion properties, solubility properties, adsorption energy, and asphaltene aggregation were calculated. The influences of linoelaidic acid and oleic acid molecules on aged asphalt-binder molecules were evaluated. The changes in the functional groups of the aged asphalt-binder after the addition of waste vegetable oil were analyzed by infrared spectrometry, and the changes in the microstructure of the aged asphalt-binder surface were observed by scanning electron microscopy. The results revealed that waste vegetable oil could regenerate aged asphalt-binder and significantly improve their physical and high-/low-temperature properties. Waste vegetable oil molecules are compatible with aged asphalt-binder molecules, improve their diffusion behaviour, enhance their adsorption capacity, and slightly reduce the aggregation of asphaltenes. Overall, waste vegetable oil shows great potential for the regeneration of aged asphalt-binder.

Study on road performance of asphalt mixture based on POE/PA6 modifier

A POE/PA6 modifier with increased reactivity was prepared using the twin-screw extrusion granulation process and added to the asphalt mixture. The effect of the POE/PA6 modifier on high-temperature stability, low-temperature anti-cracking, and water stability of asphalt mixture was studied. The results show that compared with the asphalt mixture mixed with recycled PE, the asphalt mixture mixed with POE/PA6 has nearly four times the rutting resistance of the former at 70°C and 1.0 MPa, the fracture energy and flexibility index are twice the former at -10°C, and the maximum bending strain and water stability are also significantly improved. This modifier shows a good engineering application prospect in highway construction and maintenance under high temperatures and heavy load traffic environments.

Effect of odour-less additive on asphalt flue gas emission and performance of asphalt and asphalt mixture

In this study odour-less additive were added to modify the asphalt properties in order to reduce the asphalt flue gas produced during the application process.Three different brands of No. 70 asphalt were chosen as the base asphalt and different dosages of odour-less additive were added to prepare the odour-less asphalt. The effect of the odour-less additive on VOCs, CO, H2S, NO and SO2 were tested by a portable detector to determine the optimal dosage. Then, a gas chromatography was adopted to further analyze the effect of odour-less additive on the compounds in the VOCs. SEM was used to investigate the mechanism of odour-less asphalt. Finally, the effect of odour-less additive on the basic performance of asphalt and on the road performance of asphalt mixtures were analyzed. Research results indicate that the optimal dosage of odour-less additive for No.70 asphalt is 0.04%; The odour-less ratio of the total emissions of the five gases can reach up to 52.9%; Crude oil and the processing technology exert relative huge influence on the concentration of VOCs and the higher the concentration of the compound, the better the odour-less effect, and the odour-less ratio of ethanethiol can reach up to 73.7%. The odour-less asphalt inhibits the volatilization of small molecular substances by increasing the specific surface area of asphalt and improving the inter-molecular cohesion, thereby achieving the purpose of reducing asphalt flue gas; odour-less additive yields little effect on the performance of asphalt and asphalt mixtures.

Research on Basalt Fiber Oil/Asphalt Absorption Performance and Test Methods Suitable for Asphalt Mixture with Different Structures

A basalt fiber asphalt mixture could improve the road performance of pavements and prolong the service life. The oil/asphalt absorption capacity of basalt fiber affects the road performance of asphalt mixtures to a certain extent. However, using kerosene as the medium to measure the oil absorption rate of bundle fibers by the vibration method, as the Chinese specifications recommends, is unreasonable. Therefore, the aim of this paper is to study the effect of the basalt fiber morphology on the oil absorption rate and the oil/asphalt absorption test methods suitable for asphalt mixtures with different structures (dense-graded and gap-graded), and to also explore the appropriate method to determine the oil/asphalt absorption rate of fiber to kerosene and asphalt. The results showed that the filamentous basalt fiber (FBF) was easier to disperse uniformly in asphalt than the bundled basalt fiber (BBF), and the oil absorption capacity of the FBF could more accurately characterize the actual working state of the fiber in the asphalt mixture. For the gap-graded asphalt mixture, the appropriate method to measure the fiber oil absorption rate is the combination of the vibration and centrifugation methods, while the fiber asphalt absorption rate is measured by the vibration method. For the dense-graded asphalt mixture, the combination of the extrusion and centrifugation methods are more reasonable to determine the fiber oil absorption rate, while the extrusion method is suitable for determining the fiber asphalt absorption rate. The concept of an effective fiber oil absorption rate is proposed to characterize the ability of fiber to adsorb kerosene in asphalt mixtures with different structures. A temperature of 160 °C is recommended as the test temperature to determine the fiber asphalt absorption rate. Kerosene as the asphalt absorption test medium could not directly reflect the ability of fiber to adsorb asphalt.

Performance evaluation of asphalt mixture reinforced by lignin and ceramic fiber

A single-adding fiber technology only plays a role in improving one performance of asphalt mixture such as high temperature or low temperature or water damage performance. Although double-adding fiber-reinforced asphalt mixtures are expected to improve overall road performance, existing research still only focuses on the analysis of a single performance. In this study, two representative fibers including lignin fiber (LF) and ceramic fiber (CF) were selected including to investigate the role of double-adding fibers in asphalt mixtures. The effect of different fiber proportions on the overall road performance of stone matrix asphalt (SMA-13) mixtures was analyzed via wheel tracking tests, low temperature bending test, moisture susceptibility test and fatigue test, etc. The results revealed that the combined addition of LF and CF exhibited superior improvements in mechanical strength, anti-rutting performance, moisture susceptibility, and fatigue life as compared to that of using either fiber alone. Specifically, compared to that of SMA mixtures using LF, the SMA mixtures using both two fibers improved in 11% dynamic stability, 8.6 % low-temperature bending stress, 2.1 % moisture susceptibility and 20 % fatigue life, respectively. And compared to that of SMA mixtures using CF, the mixtures using both two fibers increased in 11 % low-temperature bending strain and 8 % fatigue life, while improving slightly in dynamic stability, low-temperature bending stress, and moisture susceptibility respectively. Based on the results of efficiency coefficient method, the recommended ratio of LF to CF in the asphalt mixture is 1:2, providing a more balanced and comprehensive enhancement of road performances. This study provides a theoretical reference for the engineering application of improving the road performance of asphalt mixture through composite fiber blending, which can effectively enhance the service life of asphalt pavement.

In-situ micro-characteristics of fiber at the mortar transition zone in asphalt mixtures

Due to certain differences in physical and chemical properties of fibers used, there will be various defects in the internal structure of the resulted mixture from a microscopic perspective. The establishment of correlation between the microstructure characteristics and road performance of asphalt mixture has certain scientific research value. In this research, the proposed method of Resin Impregnated Mixture Slices was successfully used for the in-situ micromorphology, chemical heterogeneity and micro-mechanical properties investigation of lignin fiber, polypropylene (PP) fiber and polyester (PET) fiber at the mortar transition zone in asphalt mixtures. The box dimension presented by Fluorescence Microscope (FM) images indicates the most uniform distribution of polyester fibers. It is possible to trace methoxy group and ester group as an indicator on lignin fiber and polyester fiber in the thermodynamic distribution images of Attenuated Total internal Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR). And it was found that the fibers mainly concentrated in the inner region of asphalt mortar. In the testing mortar region of lignin, polypropylene and polyester fibers by Atomic Force Microscope-Quantitative Nano Mechanical (AFM-QNM), DMT-modulus in the areas containing fibers is 2.0 ∼ 18GPa, 1.0 ∼ 2.5GPa and 2.5 ∼ 5.0GPa, adhesion ranges from 50 ∼ 75nN, 20 ∼ 35nN, 30 ∼ 60nN, and the Dissipation values are 5.0 ∼ 15KeV, 0.5 ∼ 3.5KeV, 3.5 ∼ 7.0KeV, respectively. The mechanical properties of PP fiber modified asphalt mixture are considerably 0.5 ∼ 1.0 time lower than those of other samples due to the low-density and weak mechanical properties.

Experimental and analytical study on heating and road performance of asphalt mixture with silicon carbide and ferroferric oxide composite structure layer

Microwave heating is currently considered to be the most promising clean energy technology for asphalt pavement deicing. In order to improve the heating efficiency of pavement surface, a 10 mm silicon carbide (SiC) and ferroferric oxide (Fe3O4) composite structure layer (CSL) was designed on the pavement surface. The surface heating efficiency and road performance of asphalt mixture with CSL were investigated by laboratory experiments, and the distribution of electromagnetic and temperature fields were analyzed by numerical simulations. The experimental results show that the surface temperature of asphalt mixture with CSL was 1.64 and 1.36 times higher than that of the ordinary asphalt mixture and the asphalt mixture with SiC and Fe3O4 composite material, and it remained stable before and after repeated heating and water bath, with a difference of only 1 ℃∼1.7 ℃. The asphalt mixture with CSL had good road performance. The Marshall stability, residual stability and interlayer shear strength could remain above 10 kN, 92% and 4 MPa after repeated heating. The numerical simulation results show that the asphalt mixture mixed with microwave absorbing materials produced a larger electromagnetic field intensity. The heat of asphalt mixture with CSL was mainly concentrated on the road surface because the absorbing material was concentrated on the road surface. In contrast, because there was no difference in microwave absorption capacity throughout the asphalt mixture with SiC and Fe3O4 composite material, the heat distribution was mainly influenced by the electromagnetic field intensity. In general, asphalt mixture with CSL has higher surface heating efficiency and road performance.

Utilization of waste wind turbine blades in performance improvement of asphalt mixture

Redundant wind turbine blades (WTBs) retired from wind power facilities produce substantial waste annually and induce challenging environmental problems. As the most widely used materials for high-grade pavement construction, asphalt mixtures must have excellent high- and low-temperature performance, as well as water damage resistance, since pavement is subjected to complex loading, temperature, and humidity changes. This study proposed an asphalt mixture with the addition of two types of recycled WTB (rWTB): rWTB powders of granular sizes below 0.075 mm and rWTB fibers in the size range of 0.075–9.5 mm. First, the thermogravimetric analysis results indicated the accepted thermal stability of rWTB material for the requirement of compaction, paving, and service condition of asphalt mixtures. Second, the properties of the asphalt mixtures modified by using (i) rWTB powder (5 wt%, 10 wt%, and 15 wt% in fine filler), (ii) rWTB fiber (0.1 wt%, 0.2 wt% and 0.3 wt% in fine aggregate), and (iii) both rWTB powder and fiber were investigated by wheel tracking tests at 60°C, three-point bending tests at −10°C, and Marshall immersion tests. The experimental results showed that the rWTB asphalt mixtures could improve the overall road performance of asphalt mixtures, and that an optimal pavement performance could be obtained by the synergistic addition of rWTB powder and fiber. In addition, it was indicated that the improving mechanism of the rWTB material on the asphalt mixture was mainly attributed to its good compatibility with the asphalt binder, allowing the rWTB to strengthen asphalt mortar and improve the high- and low-temperature performance of the asphalt mixture.

Quantitative characterization of aggregates and their chemical constituents in terms of acid and alkaline indicators

The acidity and alkalinity of aggregates greatly affect the stability, demulsification rate, and road performance of asphalt mixtures. To study the effect of acidity and alkalinity and chemical composition of aggregates, five aggregates, namely limestone (S1, S2, S3, S4) and basalt (X), were studied. The pH and alkalinity values of aggregates and their main chemical compositions (MgO, Al2O3, CaO, Fe2O3, and SiO2) were tested. The pH/alkalinity measured values and pH/alkalinity composite values of the aggregates were analyzed using grey correlation and principal component analyses. The findings indicated a strong correlation between the composite and measured values for aggregate acidity and alkalinity indexes (pH: 0.9105, alkalinity: 0.9241). Additionally, the principal component analysis demonstrated that the composite values were in good agreement with the measured values (pH: R2 = 0.746, alkalinity: R2 = 0.992), which corroborated the grey correlation and regression model results, confirming significant correlations. This result indicates that the pH/alkaline index of the chemical constituents of the aggregate can be used to characterize the pH/alkaline index of the aggregate. The relationship model between aggregate and their chemical constituent’s acid and alkaline indexes can provide a theoretical reference for the in-depth study of the application of aggregate acid and alkaline in road engineering.

Research on Characterization of 3D Morphology of Coarse Aggregate Based on Laser Scanning

The morphology of coarse aggregate has a significant impact on the road performance of asphalt mixtures and aggregate characterization studies, but many studies were based on the two-dimensional morphology of coarse aggregate, which failed to consider morphological characteristics in a holistic manner. In order to quantitatively analyze the shape, angularity, and texture characteristics of roadway coarse aggregates, a rapid and accurate multiparameter characterization method of coarse aggregate 3D morphology is explored in this article. A 3D laser scanner is used to obtain the 3D point cloud data of pebble, granite, and basalt, and the solid models of the three coarse aggregates are reconstructed. In addition, the fitted ellipsoidal algorithm and Laplace smoothing algorithm are proposed for the characterization analysis of the overall shape, angularity, and surface roughness of coarse aggregate, and the variation rules of multicharacteristic parameters of coarse aggregate are summarized. The results of the study show that the ratio of the three axes of the fitted ellipsoid can be used to classify the shape of coarse aggregate into four types, among which the cubic shape accounts for the majority of the coarse aggregate. By analyzing the fitted ellipsoidal value and the change rate of angularity of coarse aggregate, it is concluded that the larger the values of both, the more angular the aggregate is. Moreover, the study finds that the fitted ellipsoidal value can characterize not only the shape of coarse aggregate, but also its angularity to some extent. Compared with the spherical value, the fitted ellipsoidal value has better variability and is more “sensitive” to the overall data. The change in surface area can well characterize the texture of coarse aggregate. When the particle size is small, the larger the surface area change rate of the coarse aggregates, the better the roughness of the aggregates, among which the surface area change rate of basalt is the largest. The influence of aggregate morphology was not adequately considered in previous studies of asphalt-aggregate adhesion, and this study provides parameter help for subsequent quantitative analysis of the relationship between asphalt-aggregate adhesion and coarse aggregate morphology.

Comparative Study on Pavement Performance of Asphalt Mixtures Modified by Calcium Sulfate Whisker and Calcium Carbonate Whisker

In order to study the effect of calcium sulfate whiskers and calcium carbonate whiskers on the road performance of asphalt mixtures, the high temperature stability, low temperature performance, and the change of water stability, the effect of two whiskers with different dosage levels on the road performance of asphalt mixture was obtained. The test results show that the calcium carbonate whiskers can improve the high temperature stability and water stability of the asphalt mixture within a certain dosage level range, but the low temperature performance has no obvious improvement effect, and adding excessive calcium carbonate whiskers will reduce the low temperature performance. The addition of calcium sulfate whiskers can significantly improve the road performance of the asphalt mixture. Under the same dosage level, the effect of calcium sulfate whiskers in improving road performance is better than that of calcium carbonate whiskers. When the content of calcium sulfate whisker is 0.4%, the road performance improvement effect of asphalt mixture is the best.

Effect of Recycled Aggregate Modification on the Properties of Permeable Asphalt Concrete

This study aims to evaluate the pavement performance of permeable asphalt concrete (PAC) produced with modified recycled coarse aggregate (RCA) based on six types of single modification methods and three types of double modification methods. Firstly, the water absorption, apparent density, and crushing value of the RCA before and after modification were tested. Subsequently, the performance of PAC with these types of modified RCA was investigated, including the optimum asphalt-aggregate ratio, water stability, high-temperature performance, and low-temperature crack. The test results show that the physical properties of RCA were improved to some extent owing to the modification methods adopted, except that the water absorption of RCA-C and RCA-PC increased by 33.5% and 32.6%, respectively, compared with that of RCA. This increase in the water absorption was attributed to the high water absorption of the cement mortar. As a whole, various modification methods have different effects on the road performance of asphalt mixtures, and soaking RCA with slag powder and silane coupling agent was prominent among them. Compared with the PAC with RCA, the Marshall stability, Marshall stability of immersion, residual stability, TSR, dynamic stability and low-temperature tensile strength of PAC with RCA-SLSC were increased by 31.8%, 41.0%, 7.0%, 5.8%, 280.7% and 17.2%, respectively.

Research on the Road Performance of Asphalt Mixtures Based on Infrared Thermography.

Temperature segregation during the paving of asphalt pavements is one of the causes of asphalt pavement distress. Therefore, controlling the paving temperature is crucial in the construction of asphalt pavements. To quickly evaluate the road performance of asphalt mixtures during paving, in this work, we used unmanned aerial vehicle infrared thermal imaging technology to monitor the construction work. By analyzing the temperature distribution at the paving site, and conducting laboratory tests, the relationship between the melt temperature, high-temperature stability, and water stability of the asphalt mix was assessed. The results showed that the optimal temperature measurement height for an unmanned aerial vehicle (UAV) with an infrared thermal imager was 7–8 m. By coring the representative temperature points on the construction site and then conducting a Hamburg wheel tracking (HWT) test, the test results were verified through the laboratory test results in order to establish a prediction model for the melt temperature and high-temperature stability of y = 10.73e0.03x + 1415.78, where the predictive model for the melt temperature and water was y = −19.18e−0.02x + 98.03. The results showed that using laboratory tests combined with UAV infrared thermography could quickly and accurately predict the road performance of asphalt mixtures during paving. We hope that more extensive evaluations of the roadworthiness of asphalt mixtures using paving temperatures will provide reference recommendations in the future.

Recycling waste disposable medical masks in improving the performance of asphalt and asphalt mixtures

Disposable medical masks (DMM) are a necessity for epidemic prevention, but massive waste DMM have caused serious environmental issues globally, posing potential pollutions in soil and water resources. This study aims to utilize waste DMM as modifier to prepare durable modified asphalt. The chemical composition of the waste DMM was identified by infrared spectrum. Then the waste DMM were used to modify base asphalt and their physical properties, rheological behaviors and low temperature cracking resistance were investigated. Moreover, the modification mechanism, thermal stability and morphology of waste DMM modified asphalt were analyzed by FTIR, TGA and Fluorescence Microscope (FM) and Scanning Electron Microscope (SEM). In addition, the prepared DMM fiber was used as an additive of asphalt mixture, and its influence on the road performance of asphalt mixture was investigated. The results indicated that incorporating waste DMM elevated the complex modulus, rotational viscosity, tensile elongation and decrease the phase angle of base asphalt, resulting in an enhancement effect on its high and low temperature performance. The modification process of waste DMM with a chemical composition of polypropylene was mainly a physical blend. DMM fluctuated little on the thermal stability of asphalt. Waste DMM and asphalt demonstrated superior compatibility based on the results of microscopic analysis. The addition of DMM could improve the moisture susceptibility, rutting resistance and cracking resistance of asphalt mixture. Overall, waste DMM can be recycled to modify asphalt in road construction.

Road Performance and Ice-Melting Characteristics of Steel Wool Asphalt Mixture

Elastic pavements, low-freezing point pavements, and energy exchange pavements meet the function of road ice and snow melting but may damage the pavement performance. To solve the above problems, this study intends to develop a noncontact snow-melting pavement by using induction heating technology. The steel wool asphalt mixture was prepared, and the effects of steel wool on road performances including the high-temperature performance, low-temperature performance, water stability, and fatigue performance were studied. The influence of the asphalt mixture’s factors, environmental factors, and human factors on the ice-melting characteristics of steel wool asphalt mixture was analyzed. A prediction model of the ice-melting rate of steel wool asphalt mixture based on a double-hidden layer backpropagation (BP) neural network was established. The results show that the road performance of the asphalt mixture mixed with steel wool mostly meets the requirements of the specification. The increase in steel wool content and length can improve the road performance to a certain extent. In terms of ice-melting performance, the content and length of steel wool have a beneficial effect on the ice-melting rate. The lower the ambient temperature or the thicker the ice layer, the slower the ice-melting rate. The greater the heating intensity, the faster the ice-melting rate. The average absolute error of the melting ice prediction model is 0.016, so the melting ice effect can be well predicted by this model.

Research on Three-Dimensional Morphological Characteristics Evaluation Method and Processing Quality of Coarse Aggregate

The size, shape, gradation and appearance of aggregate have a significant impact on the road performance of asphalt mixtures, which is directly related to the deformation characteristics and fatigue resistance of asphalt mixtures. In order to be able to design a long-life asphalt pavement, the aggregate must have reasonable morphology and morphological characteristics. In order to quantitatively analyze the shape characteristics of the road coarse aggregate, a high-precision three-dimensional scanner is used to obtain the characteristic lattice of the aggregate surface, and the solid model of the coarse aggregate particles is established. The two-dimensional and three-dimensional morphological indicators of the aggregate are analyzed and discussed. Meanwhile, aggregates processed by typical quarries in Guangdong Province are collected, and the influence of different processing techniques on the morphology of aggregates are analyzed. The results show that the difference between the perimeter and projected area of the aggregate contour under different viewing angles is relatively large, which is closely related to the flatness index of the aggregate. It can better characterize the three-dimensional shape of the aggregate. The closer the aggregate is to the cubic state, the greater the sphericity value; the ellipsoid index calculated based on the three-dimensional circumscribed ellipsoid can better characterize the angularity of the aggregate. The worse the angularity of the aggregate, the larger the corresponding ellipsoid value. The sphericity of the aggregate processed by counter-breaking is lower, and the angularity is better. The sphericity of the aggregate processed by the shaping process is the best, but the angularity is lower. According to actual needs, different processing techniques can be combined and blended to obtain aggregate finished products with a more balanced grain shape and angularity. The richer the angularity of the coarse aggregate, the better the high-temperature stability and fatigue resistance of the asphalt mixture. However, the stability of performance indicators will become worse. In practical engineering applications, it is recommended to further combine the screening efficiency of the hot material screen of the mixing plant with the stability of the hot material gradation and the uniformity of construction quality to select a suitable aggregate processing technology.

Investigation of the Road Performance of AH-30 Bitumen and Its Mixture: Comparison with AH-70 and SBS-Modified Bitumen

AH-30 is a type of high-viscosity matrix asphalt. The asphalt mixture made by AH-30 as a binder has an excellent antirutting performance. However, the other road performance of AH-30 was still worthy of attention. This research aims to reveal the properties of AH-30 and its impact on the road performance of asphalt mixtures (AH30-AC20/25). The AH-70 neat asphalt and SBS modified asphalt were prepared for comparison. The high-temperature sensitivity and fatigue resistance of AH-30 are evaluated by the dynamic shear rheological (DSR) test. The low-temperature performance is evaluated by the bending beam rheometer (BBR) test. The high-temperature stability (HTS) of AH30-AC20/25 is carried out by the wheel tracking (WT) test and the repeated shear constant height (RSCH) test. The low-temperature crack resistance (LTCR) is carried out by the direct stretching (DS) test. The fatigue property is carried out by the three-point bending test. Water stability (WS) is carried out by the Marshall residual stability (MRS) and the intensity ratio of the frozen and melted (IRFM) test. The test results show that the high-temperature resistance of AH-30 is better than that of AH-70. The low-temperature crack resistance of AH-30 is equivalent to that of AH-70. The AH-30 as a binder can meet the requirements of the roads, which are located at a minimum temperature of not less than −10.5°C in winter. The fatigue property of the AH-30 asphalt mixture is poor, which may be one reason why AH-30 asphalt pavement is more prone to cracking. The water stability of the AH30-AC (20/25) asphalt mixture can meet the specification requirements, and AH30-AC20 is better than the other two asphalt mixtures. The research of this paper will provide a basis and reference for the popularization and application of AH-30 in asphalt pavement.

Combustion properties and road performance of asphalt mixtures containing alumina trihydrate/organic montmorillonite composites

Alumina trihydrate (ATH) and organic montmorillonite (MMT) were used to improve the flame retardancy and smoke suppression properties of highway tunnel asphalt mixture. A series of laboratory tests were conducted on asphalt mixtures to evaluate the effects of ATH/MMT composites on their combustion properties and road performance. Cone calorimeter test results indicate that ATH/MMT delays the ignition time of the asphalt mixture and reduce the total and peak heat release rate of asphalt mixture, thus significantly improving the flame retardancy and smoke suppression properties. The road performance test results show that ATH/MMT additionally improves the deformation resistance, moisture damage resistance, fatigue life and temperature segregation resistance of the asphalt mixture. Although the low- temperature crack resistance of the asphalt mixture is slightly reduced, it still satisfies road performance requirements.

Laboratory investigation on road performances of asphalt mixtures using steel slag and granite as aggregate

Shortages of natural stone resources and serious environmental pollution promote the utilization of low-grade resources and solid waste. Thus, steel slag and granite could be used to substitute conventional aggregates in constructing asphalt pavement. In this study, asphalt mixtures incorporating granite and steel slag (GSAM) are prepared and subsequently compared with asphalt mixture prepared by limestone aggregate to determine the road performance of asphalt mixture. Two kinds of asphalt mixture, asphalt concrete (AC), and stone matrix asphalt (SMA) are prepared by the molding methods of Marshall compaction. Marshall stability, dynamic modulus, moisture damage resistance, rutting resistance, permanent deformation resistance, and crack resistance are evaluated on all the prepared asphalt mixtures through laboratory tests. The results signify that the road performance of AC-GSAM and SMA-GSAM are enhanced such as high-temperature stability and low-temperature crack resistance. However, due to the characteristics of steel slag, the long-term moisture damage resistance of GSAM is still further improvement and research. Conclusively, the use of steel slag and granite as an aggregate substitute in asphalt mixture is technically appropriate.