In recent years,the amount of waste generated during milling has increased dramatically,and improper disposal poses a significant environmental challenge.To mitigate environmental pollution and enhance the road perfor...In recent years,the amount of waste generated during milling has increased dramatically,and improper disposal poses a significant environmental challenge.To mitigate environmental pollution and enhance the road performance of emulsified asphalt cold recycled mixtures(ECRM),this study employed recycled asphalt pavement(RAP)and reclaimed inorganic binder stabilized aggregate(RAI)as dual recycled materials for ECRM preparation.The blending ratios of reclaimed base and surface layer mixtures significantly influence ECRM's performance,with adjusted proportions substantially improving compressive strength and dynamic modulus.Firstly,three distinct proportioning options were developed for the recycled materials.Mix designs incorporating varying RAP/RAI ratios were used to determine the optimal mix parameters:moisture content,cement dosage,and emulsified asphalt content.Subsequently,comprehensive performance evaluations were conducted through high-temperature wheel tracking tests,freeze-thaw splitting tests,uniaxial compression tests,and dynamic modulus measurements to analyze the pavement characteristics of the three ECRM formulations.Experimental results demonstrate:Compared with ECRM with a blending ratio of RAP:RAI:new aggregate=30:50:20(Option 1),the dynamic stability,freeze-thaw splitting strength ratio,compressive strength,and compressive resilient modulus of ECRM under Option 3(RAP:RAI:new aggregate=50:30:20)decreased by 31.8%,5.2%,16.4%,and 13.1%,respectively.This indicates that increasing RAP content while reducing RAI proportion enhances the tensile strength of ECRM,yet adversely affects its high-temperature stability,moisture resistance,and compressive performance.This work not only addresses the challenge of jointly utilizing asphalt pavement waste and base waste,but also provides a cost-effective and sustainable method for the stable application of milling material resources in road engineering.展开更多
In order to study the application of gyratory compaction molding method in emulsified asphalt cold recycled mixture and optimize the relevant technical parameters, the study was carried out according to splitting stre...In order to study the application of gyratory compaction molding method in emulsified asphalt cold recycled mixture and optimize the relevant technical parameters, the study was carried out according to splitting strength, stability and water stability test;the design of the experiment involved changing gyration number, emulsified asphalt and water content, molded specimen temperature and other factors to analyze the volume parameters, mechanical properties and water stability. The results show that both the maximum dry density and dry and wet splitting strength ratio(DWSSR) of emulsified asphalt cold reclaimed mixture are improved by the rotary compacting method, while the porosity and the optimal dosage of water are reduced. Furthermore, with the increase of compaction times, the porosity and splitting strength index both change exponentially. DWSSR and porosity are consistent with quadratic functions. The use of gyratory compaction for 70 times at 25 °C and the optimum dosage of emulsified asphalt can be determined based on the splitting strength ratio. The high-temperature stability and water damage resistance of the pavement can be improved by the use of rotary compacting method effectively, and the early strength and road performance are higher than the regulatory requirements.展开更多
In recent years,with the improvement of the requirements of road performance,modified emulsified asphalts with better performance has gradually replaced the emulsified asphalt and become the primary material for road ...In recent years,with the improvement of the requirements of road performance,modified emulsified asphalts with better performance has gradually replaced the emulsified asphalt and become the primary material for road maintenance.This paper introduces the modified emulsified asphalt materials commonly used in pavement maintenance projects,definitions and modified mechanisms of polymerized styrene butadiene rubber(SBR)modified emulsified asphalt,styrene butadiene styrene block polymer(SBS)modified emulsified asphalt and waterborne epoxy resin(WER)modified emulsified asphalt are summarized.The analysis focused on comparing the effects of modifiers,preparation process,auxiliary additives,and other factors on the performance of modified emulsified asphalt.In this paper,it is considered that the greatest impact on the performance of emulsified asphalt is the modifier,emulsifier mainly affects the speed of breaking the emulsion,stabilizers on the basic performance of emulsified asphalt evaporative residue is small;and when the modifier is distributed in the asphalt in a network,the dosage at this time is the recommended optimum dosage.Finally,this study recommends that in the future,the polymer-asphalt compatibility can be improved through composite modification,chemical grafting and other methods to continue to develop broader applicability and better performance of modified emulsified asphalt.展开更多
Under repeated train-induced loads, cement and emulsified asphalt mortar(CA mortar) as a viscoelastic material has a time-dependent deformation, part of which is irreversible. This could lead to debonding between the ...Under repeated train-induced loads, cement and emulsified asphalt mortar(CA mortar) as a viscoelastic material has a time-dependent deformation, part of which is irreversible. This could lead to debonding between the mortar layer and the track slab. Based on the theory of viscoelasticity and the analytical method of the time hardening law(THL), the viscoelastic deformation behavior of CA mortar was studied. Using ABAQUS, we established a solid model of China railway track system(CRTS) Ⅰ prefabricated slab track, with CA mortar at different initial Young’s moduli under cyclic loading corresponding to the influence of actual train loads. The results reveal that the fitted parameters of the THL for CA mortar are suitable for describing its viscoelastic deformation. As the initial Young’s modulus increases, the strain difference before and after cyclic loading gradually decreases, and the displacement difference increases from 0.2 mm to 0.6 mm. The deformation mainly occurs at the end of a mortar layer with longitudinal distribution of about 2.5 times the fasteners’ spacing. It follows that the viscoelastic performance of CA mortar is one of the most important reasons that cause debonding underneath the track slab. Therefore, we suggest that the adverse effects of viscoelastic behavior of CA mortar should be considered when researching such deformation and damage.展开更多
The slurry scaling with cationic emulsified asphalt, which is a new technique in highway construction, is rapidly extended at home and abroad. The technique should apply an excellent slow set cationic cmulsincr. Now, ...The slurry scaling with cationic emulsified asphalt, which is a new technique in highway construction, is rapidly extended at home and abroad. The technique should apply an excellent slow set cationic cmulsincr. Now, slow set emulsificrs are ligninamines which are synthesized by trimethylamine-epichlorohydrin route. Owing to high price and unstable quality, the extending of slurry sealing technique is affected seriously. We prepare the ligninaminc by a novel synthetic method. By the novel method, the cost of production is reduced by more than 30%, and the products have stable quality, high emulsifying function and broad adaptability for various asphalts. The novel synthetic method uses soda lignin, secondary amines and inexpensive aminating assistants as raw materials. The technological process of the method may use either one or two-step process, and the technological condition arc uncomplicated and easy to master.展开更多
In this work,C@Fe_(3)O_(4) composites were prepared through a typical template method with emulsified asphalt as carbon source,ammonium ferric citrate as transition metal oxide precursor,and NaCl as template.As an ano...In this work,C@Fe_(3)O_(4) composites were prepared through a typical template method with emulsified asphalt as carbon source,ammonium ferric citrate as transition metal oxide precursor,and NaCl as template.As an anode for lithium-ion batteries,the optimized C@Fe_(3)O_(4)-1:2 composite exhibits an excellent reversible capacity of 856.6 mA·h·g^(-1)after 100 cycles at 0.1A·g^(-1)and a high capacity of 531.1mA·h·g^(-1)after 300 cycles at 1 A·g^(-1),much better than those of bulk carbon/Fe_(3)O_(4) prepared without NaCl.Such remarkable cycling performance mainly benefits from its well-designed structure:Fe_(3)O_(4) nanoparticles generated from ammonium ferric citrate during pyrolysis are homogenously encapsulated in graphitized and in-plane porous carbon nanocages derived from petroleum asphalt.The carbon nanocages not only improve the conductivity of Fe_(3)O_(4),but also suppress the volume expansion of FesO4 effectively during the charge discharge cycle,thus delivering a robust electrochemical stability.This work realizes the high value-added utilization of low-cost petroleum asphalt,and can be extended to application of other transition-metal oxides-based anodes.展开更多
为研究激活作用下乳化沥青冷再生混合料强度的增强机理,首先研究激活作用下乳化沥青冷再生混合料路用性能的演变,继而通过扫描电子显微镜(scanning electron microscopy,SEM)、能量色散谱仪(energy dispersive spectroscopy,EDS)和原子...为研究激活作用下乳化沥青冷再生混合料强度的增强机理,首先研究激活作用下乳化沥青冷再生混合料路用性能的演变,继而通过扫描电子显微镜(scanning electron microscopy,SEM)、能量色散谱仪(energy dispersive spectroscopy,EDS)和原子力显微镜(atomic force microscopy,AFM)研究激活作用下界面过渡区(interfacial transition zone,ITZ)的形貌变化,分析混合料强度与界面过渡区形貌间的关系。结果表明:在乳化沥青冷再生混合料中加入激活剂能够有效提高其高温性能、低温性能和水稳定性能,激活乳化沥青冷再生混合料的15℃劈裂强度较不掺加激活剂的乳化沥青冷再生混合料提高达30.8%;激活乳化沥青冷再生混合料的界面结构紧密,随着养生时间的增加,界面过渡区宽度逐渐减小。激活作用下养生7 d的界面过渡区宽度与未激活状态下相比减小了77.8%。激活作用下旧沥青中的轻质组分可以得到有效补充,同时,激活剂中的苯乙烯-丁二烯-苯乙烯嵌段共聚物(styrence-butadiene-styrence,SBS)可以扩散到旧沥青中进行改性,从而促进了新旧沥青的融合。展开更多
基金sponsored by National Natural Science Foundation of China(No.52308466)SASAC Science and Technology Innovation Project(JF-23-01-0063)Shaanxi Provincial Transportation Research Project(25-84 K,25-85 K).
文摘In recent years,the amount of waste generated during milling has increased dramatically,and improper disposal poses a significant environmental challenge.To mitigate environmental pollution and enhance the road performance of emulsified asphalt cold recycled mixtures(ECRM),this study employed recycled asphalt pavement(RAP)and reclaimed inorganic binder stabilized aggregate(RAI)as dual recycled materials for ECRM preparation.The blending ratios of reclaimed base and surface layer mixtures significantly influence ECRM's performance,with adjusted proportions substantially improving compressive strength and dynamic modulus.Firstly,three distinct proportioning options were developed for the recycled materials.Mix designs incorporating varying RAP/RAI ratios were used to determine the optimal mix parameters:moisture content,cement dosage,and emulsified asphalt content.Subsequently,comprehensive performance evaluations were conducted through high-temperature wheel tracking tests,freeze-thaw splitting tests,uniaxial compression tests,and dynamic modulus measurements to analyze the pavement characteristics of the three ECRM formulations.Experimental results demonstrate:Compared with ECRM with a blending ratio of RAP:RAI:new aggregate=30:50:20(Option 1),the dynamic stability,freeze-thaw splitting strength ratio,compressive strength,and compressive resilient modulus of ECRM under Option 3(RAP:RAI:new aggregate=50:30:20)decreased by 31.8%,5.2%,16.4%,and 13.1%,respectively.This indicates that increasing RAP content while reducing RAI proportion enhances the tensile strength of ECRM,yet adversely affects its high-temperature stability,moisture resistance,and compressive performance.This work not only addresses the challenge of jointly utilizing asphalt pavement waste and base waste,but also provides a cost-effective and sustainable method for the stable application of milling material resources in road engineering.
基金Projects(51708048,51704040)supported by the National Natural Science Foundation of ChinaProject(17C0050)supported by the Scientific Research Project of Hunan Provincial Department of Education for General Scholars,China+1 种基金Project(kfj160103)supported by the Open Fund of State Engineering Laboratory of Highway Maintenance Technology(Changsha University of Science&Technology),ChinaProject supported by the Open Fund of Guangxi Key Lab of Road Structure and Materials,China
文摘In order to study the application of gyratory compaction molding method in emulsified asphalt cold recycled mixture and optimize the relevant technical parameters, the study was carried out according to splitting strength, stability and water stability test;the design of the experiment involved changing gyration number, emulsified asphalt and water content, molded specimen temperature and other factors to analyze the volume parameters, mechanical properties and water stability. The results show that both the maximum dry density and dry and wet splitting strength ratio(DWSSR) of emulsified asphalt cold reclaimed mixture are improved by the rotary compacting method, while the porosity and the optimal dosage of water are reduced. Furthermore, with the increase of compaction times, the porosity and splitting strength index both change exponentially. DWSSR and porosity are consistent with quadratic functions. The use of gyratory compaction for 70 times at 25 °C and the optimum dosage of emulsified asphalt can be determined based on the splitting strength ratio. The high-temperature stability and water damage resistance of the pavement can be improved by the use of rotary compacting method effectively, and the early strength and road performance are higher than the regulatory requirements.
基金The authors acknowledge the financial support from National Natural Science Foundation of China(No.51968006).
文摘In recent years,with the improvement of the requirements of road performance,modified emulsified asphalts with better performance has gradually replaced the emulsified asphalt and become the primary material for road maintenance.This paper introduces the modified emulsified asphalt materials commonly used in pavement maintenance projects,definitions and modified mechanisms of polymerized styrene butadiene rubber(SBR)modified emulsified asphalt,styrene butadiene styrene block polymer(SBS)modified emulsified asphalt and waterborne epoxy resin(WER)modified emulsified asphalt are summarized.The analysis focused on comparing the effects of modifiers,preparation process,auxiliary additives,and other factors on the performance of modified emulsified asphalt.In this paper,it is considered that the greatest impact on the performance of emulsified asphalt is the modifier,emulsifier mainly affects the speed of breaking the emulsion,stabilizers on the basic performance of emulsified asphalt evaporative residue is small;and when the modifier is distributed in the asphalt in a network,the dosage at this time is the recommended optimum dosage.Finally,this study recommends that in the future,the polymer-asphalt compatibility can be improved through composite modification,chemical grafting and other methods to continue to develop broader applicability and better performance of modified emulsified asphalt.
基金Project supported by the National Natural Science Foundation of China(No.51578472)。
文摘Under repeated train-induced loads, cement and emulsified asphalt mortar(CA mortar) as a viscoelastic material has a time-dependent deformation, part of which is irreversible. This could lead to debonding between the mortar layer and the track slab. Based on the theory of viscoelasticity and the analytical method of the time hardening law(THL), the viscoelastic deformation behavior of CA mortar was studied. Using ABAQUS, we established a solid model of China railway track system(CRTS) Ⅰ prefabricated slab track, with CA mortar at different initial Young’s moduli under cyclic loading corresponding to the influence of actual train loads. The results reveal that the fitted parameters of the THL for CA mortar are suitable for describing its viscoelastic deformation. As the initial Young’s modulus increases, the strain difference before and after cyclic loading gradually decreases, and the displacement difference increases from 0.2 mm to 0.6 mm. The deformation mainly occurs at the end of a mortar layer with longitudinal distribution of about 2.5 times the fasteners’ spacing. It follows that the viscoelastic performance of CA mortar is one of the most important reasons that cause debonding underneath the track slab. Therefore, we suggest that the adverse effects of viscoelastic behavior of CA mortar should be considered when researching such deformation and damage.
文摘The slurry scaling with cationic emulsified asphalt, which is a new technique in highway construction, is rapidly extended at home and abroad. The technique should apply an excellent slow set cationic cmulsincr. Now, slow set emulsificrs are ligninamines which are synthesized by trimethylamine-epichlorohydrin route. Owing to high price and unstable quality, the extending of slurry sealing technique is affected seriously. We prepare the ligninaminc by a novel synthetic method. By the novel method, the cost of production is reduced by more than 30%, and the products have stable quality, high emulsifying function and broad adaptability for various asphalts. The novel synthetic method uses soda lignin, secondary amines and inexpensive aminating assistants as raw materials. The technological process of the method may use either one or two-step process, and the technological condition arc uncomplicated and easy to master.
基金supported by the National Natural Science Foundation of China(51402030)the Chongqing Special Key Project of Technological Innovation and Application Development(CSTB2022TIAD-KPX0031)+2 种基金the Team Building Project for Graduate Tutors in Chongqing(JDDSTD2022006)the Research and Innovation Program for Graduate Students in Chongqing(2023S0090)the National Innovation and Entrepreneurship Projects for College Students(202310618015).
文摘In this work,C@Fe_(3)O_(4) composites were prepared through a typical template method with emulsified asphalt as carbon source,ammonium ferric citrate as transition metal oxide precursor,and NaCl as template.As an anode for lithium-ion batteries,the optimized C@Fe_(3)O_(4)-1:2 composite exhibits an excellent reversible capacity of 856.6 mA·h·g^(-1)after 100 cycles at 0.1A·g^(-1)and a high capacity of 531.1mA·h·g^(-1)after 300 cycles at 1 A·g^(-1),much better than those of bulk carbon/Fe_(3)O_(4) prepared without NaCl.Such remarkable cycling performance mainly benefits from its well-designed structure:Fe_(3)O_(4) nanoparticles generated from ammonium ferric citrate during pyrolysis are homogenously encapsulated in graphitized and in-plane porous carbon nanocages derived from petroleum asphalt.The carbon nanocages not only improve the conductivity of Fe_(3)O_(4),but also suppress the volume expansion of FesO4 effectively during the charge discharge cycle,thus delivering a robust electrochemical stability.This work realizes the high value-added utilization of low-cost petroleum asphalt,and can be extended to application of other transition-metal oxides-based anodes.
文摘为研究激活作用下乳化沥青冷再生混合料强度的增强机理,首先研究激活作用下乳化沥青冷再生混合料路用性能的演变,继而通过扫描电子显微镜(scanning electron microscopy,SEM)、能量色散谱仪(energy dispersive spectroscopy,EDS)和原子力显微镜(atomic force microscopy,AFM)研究激活作用下界面过渡区(interfacial transition zone,ITZ)的形貌变化,分析混合料强度与界面过渡区形貌间的关系。结果表明:在乳化沥青冷再生混合料中加入激活剂能够有效提高其高温性能、低温性能和水稳定性能,激活乳化沥青冷再生混合料的15℃劈裂强度较不掺加激活剂的乳化沥青冷再生混合料提高达30.8%;激活乳化沥青冷再生混合料的界面结构紧密,随着养生时间的增加,界面过渡区宽度逐渐减小。激活作用下养生7 d的界面过渡区宽度与未激活状态下相比减小了77.8%。激活作用下旧沥青中的轻质组分可以得到有效补充,同时,激活剂中的苯乙烯-丁二烯-苯乙烯嵌段共聚物(styrence-butadiene-styrence,SBS)可以扩散到旧沥青中进行改性,从而促进了新旧沥青的融合。
