In general, it can be observed that the softening point of MACRMA increased with the increase in aging temperature and time. The G*/sin δ values for the MACRMA regarding an increased frequency after aging temperature and aging time, respectively, are shown in Figure 6.
Conclusions
Effect of crumb rubber surface area and size on high temperature properties of crumb rubber modified binders. Effect of short-term aging on the high-temperature properties of shredded rubber-modified asphalt. Mod.
Determination of Construction Temperatures of Crumb Rubber Modified Bitumen Mixture Based on
Introduction
There is limited research on the construction temperatures of the CRMB mix, if any, based on the air voids of the CRMB mix. Therefore, the determination of the construction temperatures of the CRMB mixture based on the viscosity of the CRMB mastic is studied.
Materials and Methods 1. Raw Materials
In this study, the viscosity of the CRMB putty was used to determine the construction temperatures of the CRMB mixture, and the temperatures were verified with the air voids of the CRMB mixture. The filler ratio was between the weight of mineral dust and rubber bitumen.
Results and Discussion
Therefore, these construction temperatures determined based on the viscosity of the CRMB binder are inaccurate. The best air voids of the CRMB mixture were used to calculate the viscosity ranges of the construction temperatures.
Mesostructural Modeling of Dynamic Modulus and Phase Angle Master Curves of Rubber Modified
- Theoretical Background
- Experiment and Parameter Acquisition
- Construction of the Finite Element Model
- Simulation Results and Analysis
- Conclusions
We study the influence of the aggregate modulus on the dynamic modulus and phase angle of the asphalt mixture. The finite element model could accurately predict the dynamic modulus and phase angle master curves of the asphalt mixture.
Aging Characteristics of Bitumen from Different Bituminous Pavement Structures in Service
Materials and Methods 1. Materials
Therefore, the aging degree of bitumen from the bottom layer is more severe than bitumen from the middle layer. Therefore, the aging rate of the bitumen from the middle layer was slightly higher than that of the bitumen from the bottom layer.
Conclusions and Recommendations
Rheological and chemical evaluation of the aging properties of SBS polymer-modified bitumen: From the laboratory to the field. Constr. Effect of aging on chemical and rheological properties of SBS-modified asphalt with different compositions.Constr.
Evaluating the Effects of High RAP Content and Rejuvenating Agents on Fatigue Performance of Fine
Bending Test
Materials and Test Procedures
According to the manufacturer's recommendations, the RA content was 10% of the total weight of asphalt. The target gradation and binder content of FAM blends were determined by solvent extraction of the fine HMA portion (<2.36 mm), which was suggested by Yuan et al. To examine the repeatability of the tests, three repeat tests were performed for each group of FAM blends.
A viscoelastic parameter is indispensable to characterize damage property in VECD analysis, which is defined as the slope of the master curve (dynamic modulus versus load frequency on log-log diagram) in the LVE region [21]. The test temperature and load frequency of the TS test corresponded to the LAS test (20◦C, 10 Hz).
Results and Discussion 1. Frequency Sweep Test
As an illustration, Figure 6 shows repeated LAS test results of FAM mixtures with untreated binder. The LAS test results of all four groups of FAM mixes are shown in Figure 7. In this study, a flexural buckling test method using DMA was proposed for FAM mixes with high RAP content.
Using this method, four groups of FAM mixtures were tested to investigate the impact of RAP content on fatigue properties and effectiveness of RA. In conclusion, the LAS test under bending bending mode is considered as a new method to test the dynamic properties and fatigue behavior of FAM mixtures.
Synthesis and Effect of Encapsulating Rejuvenator Fiber on the Performance of Asphalt Mixture
Materials and Test Methods
In addition, the addition of fibers can improve the flexural modulus of the asphalt mixture. It can be observed that the TSR of the asphalt mixture decreased slightly when fibers were added. A four-point flexural fatigue test was performed to evaluate the resistance of the fiber asphalt mixture.
The self-healing capacity of asphalt mixture with the fiber was tested by 3PB experiment and the result is shown in Figure 9. After that, road performance and self-healing ability of asphalt mixture containing the fiber was investigated.
The Effect of UV Irradiation on the Chemical
Structure, Mechanical and Self-Healing Properties of Asphalt Mixture
Materials and Experimental Methods 1. Materials
The temperature in the chamber of the UV aging simulation instrument was 25◦C, it was tested by the temperature sensor in the chamber. The surface temperature of the asphalt mixture was about 50◦C, it was tested by an infrared temperature tester (SMART SENSOR AR-300+, SMART SENSOR, Hong Kong, China). This absorption band was very distinct and could be found in the FTIR spectrum of the virgin asphalt binder.
The schematic diagram of the half-circular bend test of asphalt concrete is shown in Figure 4. Meanwhile, a CT scanning machine (Xradia 510 Versa, ZEISS, Oberkochen, Germany) was used to characterize the crack size of asphalt concrete samples before and after self-healing.
Results and Discussions
The recovery percentages of semicircular flexural strength of asphalt concrete were calculated according to equation (4). The recovery percentages of semicircular bending strength (HPBS) values of asphalt concrete before and after UV irradiation are listed in Figures 10 and 11. BS before aging and BS after aging are the recovery percentages of semicircular bending strength of asphalt concretes before and after UV aging, MPa, respectively.
Initial fatigue life and fatigue life after self-healing of asphalt concrete are shown in Table 5. The HPFL values for asphalt concrete after different times of UV irradiation are given in Figure 12.
Investigation of the Effect of Induction Heating on Asphalt Binder Aging in Steel Fibers Modified
Materials and Experiments 1. Materials
The main curves of complex moduli and phase angles of asphalt binders after induction heating in different states are shown in Figures 12 and 13, respectively. After induction heating for 10 cycles, IC=O reached 0.006231, which showed that the aging of the asphalt binder was very obvious at that time. In addition, the component fractions of DA were comparable to those of the asphalt binder after induction heating for 3 cycles.
In this study, the effect of induction heating on the aging of asphalt binder in steel fiber modified asphalt concrete has been investigated. Study of the gradient heating and healing behavior of asphalt concrete caused by induction heating.Constr.
Study of the Self-Healing Performance of
Semi-Flexible Pavement Materials Grouted with Engineered Cementitious Composites Mortar based
Experimental Design
The self-healing properties of ECC mortar were evaluated based on the shear strength test. The self-healing properties of the SFP materials were evaluated based on the three-point bending test. According to Figure 11a, the three-point flexural strength increased as the void ratio of the asphalt matrix mixture increased.
According to Figure 11b, the void ratio of the matrix asphalt mixture affected the maximum flexural strain. Meanwhile, the maximum bending stress of the SFP materials decreased with the increase of the void ratio.
Laboratory and Numerical Investigation of
Microwave Heating Properties of Asphalt Mixture
- Materials and Methods
- Numerical Simulation
- Results and Discussions 1. Numerical Simulation Results
- Conclusions
The magnetism of the asphalt mixture introduced by the ferrite additives is responsible for the magnetic loss during microwave heating. The temperature distribution of two types of asphalt mixture after 120 s simulated microwave heating is shown in Figure 8. However, it is possible to use a numerical method to simulate the microwave heating process of asphalt mixture.
This study investigated the microwave heating properties of two types of asphalt mixture through laboratory test and numerical simulation. Microwave heating of an asphalt mixture sample containing steel slag involves both resistive heating and magnetic heating due to the altered permeability of the sample.
Preparation and Characteristics of Ethylene
Bis(Stearamide)-Based Graphene-Modified Asphalt
Experimental Method and Performance Evaluation
The shear processing of the modified asphalt was performed using a BME200L intense shear and mixing emulsion machine (motor power 0.4 kw, rotation speed range 0–10,000 r.p.m.) from Shanghai Weikang Machine Manufacturing Co., Ltd., Shanghai, China. The ultrasonic separation of the graphene mixture solution was performed using JP-040 ultrasonic equipment (ultrasonic wave power: 240 W, ultrasonic wave frequency: 40 kHz) from Skymen Cleaning Equipment Shenzhen Co., Ltd., Shenzhen, China. The rheological performance of the asphalt was tested with a Bohlin DSR I dynamic shear rheometer from Malvern Panalytical Instrument Co., Ltd., Malvern, UK.
The graphene dispersion in GMA was observed using a DM6 M microscope from Leica Microsystems Inc. The GMA structure was characterized via XRD (from Bruker Corporation, Karlsruhe, Germany) and a fluorescence microscope (from Leica Microsystems Inc. Co., Ltd., Buffalo Grove, IL, USA).
Results and Discussion 1. Indices Data Analysis
Test group B-1 had the most significant improvement in performance; therefore, test parameters B-1 are selected as optimal parameters of GMA mixture: high-speed cutting speed is 6500 r.p.m.; cutting time is 180 min; the proportion of graphene is 20‰; the proportion of EBS is 1%; and the cutting temperature is 140◦C. Based on Bragg's law, 2dsinθ= nλ, the interplanar spacing is d1= 0.472 nm and has an extremely weak peak at 2θ= 9.6◦; the interplanar spacing is d2= 0.921 nm, which is a structure with loose layers of asphalt or aggregated gum. Figures 7 and 8 show that the dispersant has significantly different effects of graphene dispersion in different test groups (i.e., the dispersion of graphene in asphalt is affected by changes in parameters including the ratio of dispersant and graphene mixture, cutting rotation speed, cutting time, and cutting temperature).
For EBS-based GMA, the optimal parameters are as follows: the proportion of graphene is 20‰; the share of EBS is 1%; cutting speed at high speed is 6000 rpm; cutting time is 180 min; shear temperature is 140◦C. The prepared GMA had significantly improved softening point, low temperature fracture energy, anti-rutting factor and creep recovery rate. When the dispersion agent cannot evenly distribute the graphene in the asphalt, most of the graphene clusters in the asphalt are of medium size.
Rheological Properties, Compatibility, and Storage Stability of SBS Latex-Modified Asphalt
In this study, the preparation process of the SBS latex modified asphalt is shown in Figure 2. Meanwhile, it was found that the viscosity values of SBS latex modified asphalt B were all lower than those of modified asphalt A. This indicates that the SBS latex modified asphalt had worse compatibility than the conventional SBS particle modified asphalt.
It was found that the softening point difference of the modified asphalt increased as the SBS latex dosage increased. This paper prepared and evaluated the rheological properties, compatibility and storage stability of SBS latex modified asphalt.
Improvement of Low-Temperature Performance of Buton Rock Asphalt Composite Modified Asphalt by
Materials Preparation and Test Method
It means that the percentage of pure asphalt is the same in BRA-modified asphalt and BRA ash mortar. The ash percentage is the same in BRA-modified asphalt and BRA ash mortar, as shown in Figure 1. However, according to the BRA test data of BRA-modified asphalt in this document, 58% of the amount of BRA-modified asphalt reached the limit of asphalt's low-temperature performance at −6◦C.
To further observe the improvement in low-temperature performance of BRA-modified asphalt from SBR, the low-temperature creep-bend test was conducted in this paper. The failure strain index of the low temperature flexural test was used to evaluate the low temperature performance of the modified asphalt mixture.
Test Result
This reflects that the addition of SBR improved the low-temperature performance of the BRA-SBR composite modified asphalt. With the addition of SBR, the compliance and strength of BRA-SBR composite modified asphalt increased. When the temperature decreased, the effect of SBR improved the low-temperature performance of BRA-SBR composite modified asphalt more clearly.
Which index is more suitable for characterizing the low-temperature performance of composite modified asphalt BRA-SBR will be further studied. SBR can improve the ability of BRA-modified asphalt to withstand low temperature damage.
