AbstractCold mix asphalt (CMA) is commonly used for repairing asphalt pavement potholes. Ordinary CMA has the problems of poor construction workability and low initial strength in low-temperature ...environments. To improve pothole repair using CMA in low-temperature environments, a solvent-type cold asphalt liquid (CAL) has been developed and modified by a waterborne epoxy and styrene-butadiene rubber (WER+SBR). First, a low-temperature curing test, compatibility test of WER and SBR latex, and 60°C viscosity test of CAL were conducted and evaluated, and then the type of WER was selected. Second, an orthogonal test with four factors of diluent, WER, SBR, and tackifier was designed to analyze the effects of each factor on 60°C viscosity, adhesion grade, storage stability, and distillation residue of WER+SBR type CAL, and the best raw material ratio was determined. Finally, low-temperature construction workability and road performance of WER+SBR type CMA were evaluated. The results show that EP-20 can be used as the optimal WER for low-temperature type CAL, and the preferable composition of WER+SBR type CAL is SK90# asphalt (100): diluent (26): tackifier (5): WER (4): SBR (2). Compared with ordinary CMA, WER+SBR type CMA is excellent in initial strength, forming strength, high-temperature stability, low-temperature crack resistance, water stability, and low-temperature construction workability. WER+SBR type CMA can be applied to pothole repair in low-temperature environments, which is an important development in improving the repair of asphalt pavement potholes.
AbstractTo understand the performance of desulfurized rubber asphalt (DRA) and its application feasibility comprehensively, the road performance, viscosity–temperature characteristics, rheological ...properties, storage stability, aging resistance, and environmental performance of DRA were investigated and compared with ordinary rubber (hereinafter called rubberized rubber) asphalt. The test results showed that rubberized rubber asphalt (RRA) performs better than DRA in elastic recovery, aging resistance, and rutting resistance, but DRA performs better than RRA in storage stability and low-temperature performance. DRA has similar fatigue resistance as RRA. Compared with RRA, the construction temperature of DRA can be reduced by about 30°C, which means that DRA has better workability. The performance grade (PG) of DRA was classified as PG 76-34, which indicates that DRA has a wider temperature range and can be applied to lower-temperature environments. In addition, the harmful gas emission of DRA is lower than that of RRA, so DRA is more environmentally friendly. Therefore, it is necessary to modify DRA with compound methodologies to enlarge its application.
•A green road grouting material AASFGM was prepared at ambient temperature.•A multi-index optimization design based grey correlation and objective weighting is applied systematically.•The physical ...properties of AASFGM were tested and compared with those of cement grouting materials.•The microstructure and strength development mechanism of AASFGM was further characterized.
As a green and carbon-friendly material, alkali-activated grouting material (AAGM) has great application potential in reinforcement engineering. In this study, the alkali-activated slag/fly ash grouting material (AASFGM) was prepared with industrial-waste ground granulated blast-furnace slag (GGBS) and fly ash (FA) as raw materials. In order to meet the multi-performance requirements, a multi-index optimization design based on grey correlation and objective weight was adopted to prepare AASFGM pastes. And its physical performances including fresh and harden properties were tested and compared with those of cement grouting materials (CGM), more than that, the microstructure and strength development mechanism of AASFGM was further characterized by means of X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy-dispersive Spectrum (EDS) and Fourier transform infrared spectroscopy (FT-IR). It is found that the AASFGM paste possesses clean production, high mechanical strength, high fluidity, low bleeding rate and low porosity, providing appealing properties as grouting materials for reinforcement. The new multi-index optimization method, based on grey correlation and objective weights determined, is much more scientific and objective to obtain a balanced performance for AASFGM preparation. The optimized AASFGM paste has a uniform and compact microstructure, and it also has remarkable advantages in mechanical strength, bleeding rate and porosity compared with CGM. As a carbon-friendly grouting material, it may become a greener substitute of CGM for the cleaner reinforcement engineering.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
As a special type of joint fracture, the fracture evolution characteristics of parallel double joints have important engineering significance for the stability analysis of fractured rock mass. In ...this work, a new method for calculating stress intensity factor of parallel double-jointed fractures was importantly proposed. Physical uniaxial compression tests were carried out on parallel double jointed red sandstone filled with cement mortar under different geometric parameters, and the macroscopic mechanical properties and failure characteristics of red sandstone are deeply analyzed. The results show that the larger the connectivity rate is, the smaller the peak stress and strain are. The increase of connectivity rate will affect the change rate of transverse strain in the center of rock bridge. The closer the dip angle of the joint is, the lower the peak stress is and the shorter the failure time is. The damage mode of joint tip encroachment affects the lateral displacement of the rock bridge center, and the displacement is always close to the first damage section. The closer the joint tip is to the load, the easier the end-face penetrating cracks occur. The research content can provide basic support for guaranteeing the stability of underground engineering rock mass.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•RET modified asphalt was modified with polyurethane prepolymer (PUP).•Performance and its influencing factors of PUP/RET modified asphalt were studied.•The chemical reaction between PUP and RET ...modified asphalt was studied by FTIR.•PUP can improve the performance of RET modified asphalt and its mixture.•The optimal preparation of PUP/RET modified asphalt was put forward.
To improve the performance of Reactive Elastomeric Terpolymer (RET) modified asphalt and give full play to its role, the chemically modified material, polyurethane prepolymer (PUP), was used for composite modification. The effect of PUP content, RET content, preparation equipment, rotation speed and shear time on the performance of PUP/RET modified asphalt (PUP/RETMA) was investigated using asphalt tests. The chemical reaction between PUP and RET modified asphalt (RETMA) was confirmed using FTIR test. The high-temperature rutting resistance, low-temperature crack resistance and moisture susceptibility of several asphalt mixtures were evaluated and compared using mixture tests. The results show that PUP can improve the performance of RETMA and its mixture, especially the low-temperature performance. RET content and PUP content have the positive effect on the high and low temperature performance of PUP/RETMA, respectively. To obtain excellent performance, sufficient shearing and proper shear time are needed for the preparation of PUP/RETMA. The chemical reaction exists in the modification process of PUP and RETMA. Based on experimental study, the proper RET content and PUP content are recommended 1.5% and 8%–10% by weight of base asphalt respectively. The high-speed shear emulsifying mixer is recommended, 5000 rpm of shear speed and at least one hour of shearing are suggested. PUP can improve the performance of RETMA, thus, using PUP for composite modification is able to promote the application and popularization of RETMA.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The porous asphalt pavements is often used in important occasion for its special properties and performance which can be to a great extent attributed to the binder—high viscosity and elasticity ...asphalt (HVEA). To prepare high demanding binder for porous asphalt pavements, the polyurethane prepolymer (PUP) and styrene–butadiene–styrene (SBS) were used to modify the matrix asphalt compositely. First, based on a series of physical tests, the effects of binder composition on performance of SBS/PUP HVEA binder (SBS/PUP‐HVEA) were investigated. Then the Fourier transform infrared (FTIR) test was conducted to investigate the reaction mechanism of SBS/PUP‐HVEA binder. Last, the fluorescence microscopy, stability tests, multiple stress creep recovery test, and differential scanning calorimetry test were carried out to evaluate and compare the phase structure, storage, high‐temperature performance, thermostability characteristics of several HVEA binders. It is found that the composite modification of SBS and PUP can produce high quality binder which possesses high viscosity and high elasticity. And the composition of SBS/PUP‐HVEA were recommended as follows: Shell‐70# can be chosen as matrix asphalt, the contents of SBS modifier (SBS1301:SBS4303 = 1:2), H2122A PUP, chain extender M‐OEA, and crosslinker sulfur were suggested 4%, 5%, 0.5%, and 1‰, respectively. The new functional groups observed in FTIR confirmed the existence of physical and chemical reactions in the modification process, which were beneficial to improve the high temperature performance and storage stability of the binder. SBS/PUP‐HVEA had good phase structure, storage stability, high temperature performance, and thermostability compared to other HVEA binders. This study demonstrated that the SBS/PUP compositely modified asphalt possessed high viscosity and high elasticity, which can be used in the porous asphalt mixture and other highly demanding working environment as well.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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•Provide a new insight for exploring the UV aging mechanism of asphalt binders.•Explore the effects of some potential influencing factors and their interactions on the UV aging ...characteristics of asphalt binders with RSM method.•Characterize the micro properties of asphalt binders irradiated by UV light with different wavelengths through some microscopic experiments.
To explore the UV aging characteristics of asphalt, effects of potential influencing factors as well as their interactions on asphalt’s properties were investigated with the aid of Response Surface Methodology (RSM). Four influencing factors, including ultraviolet irritation wavelength, irritation intensity, asphalt film thickness, and aging temperature, were selected as the response variables of RSM. And complex shear modulus aging index G*AI, DSR function aging index DAI and fatigue factor aging index FAI were selected as the responses’ values. Then, the Central Composite Design (CCD) model of RSM was adopted to establish the statistical models to analyze the effects of different variables on asphalt’s UV aging behaviors. On this basis, aging degree of asphalt under ultraviolet irradiation with different wavelengths was analyzed emphatically with Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Force Microscope (AFM) tests. Meanwhile, method for speeding up the efficiency of asphalt UV aging test by reducing the asphalt film was also proposed. Test results show that UV aging rate of asphalt increases gradually with the decreasing of asphalt film and the increasing of radiation intensity and aging temperature; among them, the effect of asphalt film thickness is the greatest, while that of aging temperature is the smallest. In addition, radiations with different wavelength have different effects on UV aging behaviors of asphalt, and asphalt irradiated by UV-340 to UV-360 has the highest aging degree, which can be further proved by FTIR and AFM test results. Interactions between different factors will also affect the UV aging characteristics of asphalt, and the results are related to the types of asphalt. However, interaction between UV radiation wavelength and asphalt film thickness all have the significant effects on the UV aging behaviors of base asphalt and SBS modified asphalt. Decreasing the asphalt film thickness can effectively increase the UV aging rate of asphalt. Thus, the aging time can be appropriately reduced on the basis of thinner asphalt film, so as to improve the test efficiency. And finally, it can be found that two processes may exist during the UV aging process of asphalt, namely molecular excitation process and chemical bond breaking process. Under the two actions, unstable chemical bonds in asphalt will reach the excited state or break, and combine easily with the oxygen atom and then generate some polar oxygen-containing functional groups, thus causing the decline of asphalt’s properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Rejuvenator wets more easily on aged modified asphalt than on aged matrix asphalt.•The wetting effect of bio-rejuvenator is better than that of mineral oil rejuvenator.•Aging will adversely affect ...the wetting effect.•Rejuvenator with lower viscosity, larger surface tension and smaller contact angle is suggested to use.
In hot recycling engineering of asphalt pavement, the fusion effect between rejuvenator and RAP binder which is closely related to the wettability will remarkably affect the regeneration effect of old material. To analyze the wetting behavior and its influencing factors of rejuvenator/old asphalt interface and further to optimize the asphalt rejuvenator, the dynamic contact angles of different rejuvenators at old asphalt surface were measured by using dynamic surface tension meter. Also, based on the surface wetting theory, the wetting parameters of rejuvenator at old asphalt surface were calculated based on the contact angle test results, so as to comprehensively evaluate the wetting behavior of rejuvenator/old asphalt interface and analyze its influencing factors. The results show that it is easier for rejuvenator to wet on the surface of aged modified asphalt than on the surface of aged matrix asphalt. The deepening of aging of asphalt makes it more difficult for rejuvenator to infiltrate on its surface spontaneously, and the thermal-oxidative aging shows the similar effect as photo-oxidation aging. The wetting effect of bio-rejuvenator is better than that of mineral oil rejuvenator, and four rejuvenators can all infiltrate but cannot spread on the surface of aged asphalt. The interfacial wettability of rejuvenator/old asphalt is affected by the interaction of environmental temperature, surface tension, contact angle, viscosity and aging degree of old asphalt, and the effect of viscosity and contact angle on the interfacial wettability is stronger than that of surface tension. Therefore, when selecting asphalt rejuvenator, it is recommended to select the rejuvenator with lower viscosity, larger surface tension and smaller contact angle with aged asphalt, and the lower viscosity is especially the primary consideration. The findings deeply reveal the wetting behavior of rejuvenator/old asphalt interface, and provide a theoretical basis for the development of efficient-performance rejuvenator.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The higher permeation temperature or longer time contributed the permeation effect.•The permeability of mineral oil rejuvenator in aged asphalt was stronger than that of bio-rejuvenator.•Thinner ...aged asphalt layer made the rejuvenator more easily permeate.•Similar micro morphological and mechanical properties appeared at different layers of L-type RFLs.•L-type rejuvenator contained lower carbonyl and exhibited better permeability.
Aiming to analyze the permeation behaviors and micro characteristics of rejuvenator in old asphalt, the rejuvenation fusion layer (RFL) of rejuvenator and old asphalt was first fabricated by permeation test. Then, the viscosity of RFLs was analyzed and its several influencing factors were explored via conducting the rotational viscosity test. On this basis, coupled with Fick’s law and composite material theory, the permeability coefficient (D) of rejuvenator in old asphalt was calculated and the influencing factors were investigated. Lastly, the micro-phase morphology, mechanical and chemical characteristics of RFL were analyzed via the AFM and FTIR tests. Results showed that the permeability of rejuvenator in old asphalt depended on permeation temperature, permeation time, rejuvenator type and asphalt layer thickness. The higher permeation temperature or longer time contributed to the permeation effect of rejuvenator in old asphalt. Moreover, based on the results, the mixing temperature should not be less than 150 °C and the mixing time should be about 12 s ∼ 18 s for the uniform mixing of RAP and rejuvenator in actual thermal rejuvenation engineering. The permeability of mineral oil rejuvenator in aged asphalt was stronger than that of bio-rejuvenator, and thinner aged asphalt layer made the rejuvenator more easily permeate. Further, the sampling layer exhibited the most remarkable influence on the permeability of rejuvenator in old asphalt, followed by rejuvenator type, permeation time and permeation temperature. The AFM test confirmed that the permeation effect of mineral oil rejuvenator in aged asphalt was superior to that of bio-rejuvenator from the micro perspective, and that under the permeation conditions of 130 °C and 6 h, the mineral oil rejuvenator can fully fuse with aged asphalt and show similar morphological characteristics (“bee” size and quantity) at different layers of RFLs. Further, the mineral oil rejuvenator greatly enhanced the micro mechanical properties of aged asphalt, demonstrating a favorable rejuvenation effect. FTIR test manifested that the functional group composition of the L-type rejuvenator was similar to that of the original asphalt, and that the L-type rejuvenator contained lower carbonyl contents compared to B-type and H-type rejuvenators and exhibited better permeability and rejuvenation effect.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A new warm-mix recycling agent was developed using uniform design method.•WR improves low-temperature property and fatigue resistance of reclaimed asphalt.•WR remarkably reduces construction ...temperatures of reclaimed asphalt.•Compared with commercial rejuvenators, WR exhibits better economical benefit.
Warm-mix recycling asphalt mixture has remarkable environmental and economic benefits. In this study, a new warm-mix recycling agent (WR) was developed by using base oil (80%), surfactant (9.5%), plasticizer (8.0%) and antiaging agent (2.5%) based on uniform design method. Experimental tests including penetration, softening point, ductility, elastic recovery, dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), bending beam rheometer (BBR), linear amplitude sweep (LAS), rotational viscosity as well as Fourier transform infrared spectroscopy (FTIR) test were conducted to evaluate the properties of aged binders incorporating the WR and other two commercial rejuvenators, i.e. an emulsified rejuvenator (ER) and a resinous rejuvenator (RR). Additionally, the workability and cost of reclaimed asphalt binders were analyzed. Results indicate that the WR is able to rejuvenate conventional physical properties of aged asphalt. Reclaimed asphalt containing WR shows the best low-temperature performance and longest fatigue life than that containing other two commercial rejuvenators. With regard to high-temperature performance, reclaimed asphalt incorporating WR compares favorably with that incorporating ER. The results from FTIR test demonstrated that physical interaction dominated the rejuvenation of aged asphalt after adding the WR. WR can significantly replenish the volatiles in aged asphalt, and restore its components’ proportion that resembles the virgin asphalt. In comparison with ER and RR, WR exhibits a lower increased cost and the excellent capability of reducing mixing and compaction temperature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
