In this paper, the research on warm mix asphalt construction technology of asphalt surface course in low temperature season in cold areas is carried out. The research project is guided by surface theory, mortar theory...In this paper, the research on warm mix asphalt construction technology of asphalt surface course in low temperature season in cold areas is carried out. The research project is guided by surface theory, mortar theory, strength theory and asphalt concrete regulations, based on solid engineering practice, aiming at breaking through the bottleneck of Asphalt Mixture Construction under low temperature environment, through repeated tests and optimization. Carry out a series of studies including the selection of warm mix agent, the formula, road performance and construction technology of warm mix asphalt mixture, and start from four aspects: the selection of warm mix agent, the proportion and technology of warm mix asphalt mixture, the road performance of warm mix asphalt mixture and the construction technology of warm mix asphalt mixture expressway. It has formed a complete set of technical scheme and control standard system for selecting and determining the optimal type and dosage of warm mix agent, reasonable raw material ratio, mixing process and parameters, road performance and applicability of warm mix asphalt mixture, and construction of warm mix asphalt process in low temperature season of asphalt pavement engineering.展开更多
The fatigue behavior, indirect tensile strength （ITS） and resilient modulus test results for warm mix asphalt （WMA） as well as hot mix asphalt （HMA） at different ageing levels were evaluated. Laboratory-prepared...The fatigue behavior, indirect tensile strength （ITS） and resilient modulus test results for warm mix asphalt （WMA） as well as hot mix asphalt （HMA） at different ageing levels were evaluated. Laboratory-prepared samples were aged artificially in the oven to simulate short-term and long term ageing in accordance with AASHTO R30 and then compared with unaged specimens. Beam fatigue testing was performed using beam specimens at 25 ℃ based on AASHTO T321 standard. Fatigue life, bending stiffness and dissipated energy for both unaged and aged mixtures were calculated using four-point beam fatigue test results. Three-point bending tests were performed using semi-circular bend （SCB） specimens at -10 ℃ and the critical mode I stress intensity factor K1 was then calculated using the peak load obtained from the load-displacement curve. It is observed that Sasobit and Rheofalt warm mix asphalt additives have a significant effect on indirect tensile strength, resilient modulus, fatigue behavior and stress intensity factor of aged and unaged mixtures.展开更多
In view of the asphalt pavement structure layer dynamic shear creep properties of interface, according to the production mix of warm mix asphalt concrete mixture ratio, and through the European standard wheel rolling ...In view of the asphalt pavement structure layer dynamic shear creep properties of interface, according to the production mix of warm mix asphalt concrete mixture ratio, and through the European standard wheel rolling compaction machine forming specimen, placed in the mold of the MTS machine related series experiment, temperature, water environment and normal stress factors, to seek the dynamic shear creep displacement along with the changes in the number of cyclic loading. The dynamic creep ability of warm mix asphalt concrete is enhanced with the increase of temperature and water immersion condition. With the increase of normal stress, the displacement of dynamic shear creep in the second stage is relatively large, and the ability of warm mixed asphalt concrete to resist internal shear is enhanced.展开更多
With the continuous development of domestic highway construction,highway civil engineering and service level quality have attracted much attention.Good pavement quality and high-quality service make people feel comfor...With the continuous development of domestic highway construction,highway civil engineering and service level quality have attracted much attention.Good pavement quality and high-quality service make people feel comfortable and smooth when traveling.High-quality pavement can significantly reduce the probability of traffic accidents.At present,there is a direct relationship between pavement quality and pavement construction operations.Carrying out pavement construction operations in cold high-altitude areas requires a reasonable selection of construction equipment and methods.The application of warm-mix asphalt pavement construction technology can ensure pavement quality.Therefore,this paper analyzes the advantages of warm-mix technology,the environmental characteristics of cold high-altitude areas,and construction preparations,and discusses the construction technology of warm-mix asphalt pavement in cold high-altitude areas in detail,to improve the overall road quality of cold high-altitude areas.展开更多
To achieve environmentally friendly construction and safe operation of tunnel pavements,the mixing construction temperature of asphalt pavements needs to be reduced and the fire safety of asphalt pavements needs to be...To achieve environmentally friendly construction and safe operation of tunnel pavements,the mixing construction temperature of asphalt pavements needs to be reduced and the fire safety of asphalt pavements needs to be improved. In this paper, zeolite-based warm mix agent(WMA) and targeted flame retardants(TFR) were used for asphalt modification to reduce the mixing temperature and improve the fire safety of asphalt pavements. First, the formulation of zeolite-based warm mix flame retardant(WMFR) was optimized based on the response surface multi-satisfaction optimization method(RSMOM);then, three kinds of surface modifiers were used to surface modify for WMFR;finally, the functional properties and road performance of WMFR modified asphalt(WMFRMA) were investigated. The results showed that the surface modification could improve the compatibility and storage stability of WMFR with asphalt. The mixing temperature of Titanate coupling agent modified WMFR modified asphalt(Ti-WMFRMA) and surface active agent modified WMFR modified asphalt(Sur-WMFRMA) was reduced by about 10℃ compared with that of the matrix asphalt(JZ). But, there was no significant change in the mixing temperature of Silane coupling agent modified WMFR modified asphalt(Si-WMFRMA). The four kinds of WMFR could effectively improve the fire safety of asphalt binder and mixture. Among them, the peak heat release(PRR) of Sur-WMFRMA was 62.81% lower than that of JZ, and the peak smoke production(PSPR) of Ti-WMFRMA was 69.98% lower than that of JZ. The rheological properties of the flame retardant modified asphalt binder and the road performance of the asphalt mixture were verified, and the surface modification of WMFR could effectively improve the functional properties and road performance of asphalt.展开更多
Incorporation of warm mix asphalt （WMA） and reclaimed asphalt pavement （RAP） has benefited the asphalt industry in many ways such as reducing the demand for virgin materials, lowering energy requirement during the...Incorporation of warm mix asphalt （WMA） and reclaimed asphalt pavement （RAP） has benefited the asphalt industry in many ways such as reducing the demand for virgin materials, lowering energy requirement during the asphalt production and construction, in addition to reducing greenhouse-gas emissions. This study evaluated the effects of Evotherm and RH-WMA and RAP on mixtures＇ behavior in terms of the compaction energy index （CEI）, indirect tensile strength （ITS） and resilient modulus. The results showed that warm mix additives reduced the CEI, ITS and resilient modulus; while RAP increased the corresponding values. Statistical analysis showed that mixtures incorporating Evotherm and RAP had significant effects on CEI, while the effects of RH-WMA on the corresponding value were found to be statistically insignificant. General Linear Model showed that Evotherm, RAP and RH-WMA exhibited no significant effects on the ITS and resilient modulus. The one-way analysis of variance showed that Evotherm influenced mixture behavior significantly, while RAP and RH-WMA effects were found to be statistically insignificant. Regression equations with high accuracy levels were proposed to predict CEI, ITS and resilient modulus with respect to modification of mixture variables such as mix constituents （Evotherm, RH-WMA, and RAP） and compaction temperature.展开更多
This paper presents results from investigating the ageing behaviour and performance of different warm mix asphalt （WMA） pavement mixtures also called energy reduced pavements. The mixtures were either prepared in th...This paper presents results from investigating the ageing behaviour and performance of different warm mix asphalt （WMA） pavement mixtures also called energy reduced pavements. The mixtures were either prepared in the laboratory or taken directly from a mixing plant. The study compared the rutting and fatigue behaviours of unaged material in comparison to long term laboratory aged material. In order to conduct the long term ageing, a special laboratory ageing protocol with different heating, cooling and watering cycles had been developed. The investigation revealed a quite controversial rutting behavior which could not be explained with the available data. While most aged energy reduced pavements showed increased rutting for other mixtures, lower rut depths could be found. As opposed to this finding, fatigue and stiffness of all aged energy reduced pave- ment samples compared to unaged samples improved significantly. The overall results led to the conclusion that the ageing of energy reduced pavement simulated in the laboratory is not very critical regarding their mechanical performance. Therefore, it was confrmed that the application of this type of pavement provides a good solution for saving on CO2 emissions. Another advantage is that by using energy reduced pavements the road con- struction season can be significantly prolonged.展开更多
Warm mix asphalt （WMA} is a new technology which asphalt mix is produced and placed at normal temperature. It has advantages including low cost, environmentally friendly, haul-convenience, and so on. WMA has been wid...Warm mix asphalt （WMA} is a new technology which asphalt mix is produced and placed at normal temperature. It has advantages including low cost, environmentally friendly, haul-convenience, and so on. WMA has been widely tested and applied in the USA in the last decade, but it has just started in China. Recently, a new WMA using a new plastic- macromolecule-normal temperature additive, which was called ＂SMC＂ by the production company, was introduced as asphalt modifier. Based on discussing the strength forming process of this new WMA with SMC, a series of laboratory tests, including Marshall stability test （MST）, boiling test （BT）, modified immersion Marshall test （MIMT）, freeze-thaw split- ring test （FTST）, rutting test （RT）, low-temperature bending test （LTBT）, and abrasion loss test （ALT）, were conducted in this study to assess the performance of this WMA and the capability of applying it on low volume roads in China. SMC modified asphalt mixed under normal temperature is used in testing samples. It was found that this WMA product exhibited merits on its strength, which was about 6.7 kN bigger than the requirement of 5.0 kN in the JTG F40-2004, on high-temperature stability, which is about 1100 times/ram greater than the requirement of 600-1000 times/mm in the ）TG F40-2004, and on its storage stability. Based on these indicators, it is recommended that this product could be used for low volume low class roads construction. However, due to the relatively lower water resistance and low-temperature cracking resistance, this product is suggested to be applied first in the areas with warm weather and little rainfall. In order to improve the perfor- mance of this WMA with SMC, further research on this SMC asphalt modifier should be continued.展开更多
With the continuous improvement of the level of urbanization, the number of road construction is gradually increasing, which greatly facilitates people's travel and promotes the economic development of the city. T...With the continuous improvement of the level of urbanization, the number of road construction is gradually increasing, which greatly facilitates people's travel and promotes the economic development of the city. The quality maintenance of expressway pavement is of great significance to the safety of public traffic. To ensure the service life and quality of expressway, it is extremely important to do a good job of highway maintenance and quality control. Due to the poor maintenance effect of traditional technology and the large exposed base area of highway pavement, this paper analyzes the warm mixing ultra-thin wear layer technology used in the maintenance of expressway, hoping to provide reference for the upgrading of technology in the future.展开更多
With the rapid development of municipal engineering, the technology and scheme for the quality control of asphalt pavement concrete are becoming more and more perfect. In order to rush for work and time, paving constr...With the rapid development of municipal engineering, the technology and scheme for the quality control of asphalt pavement concrete are becoming more and more perfect. In order to rush for work and time, paving construction of some asphalt pavements is becoming more and more common in cold winter. In order to ensure the compaction quality of asphalt concrete during construction under low temperature conditions, the application of warm mix is more and more common. In this paper, SMA-13 is taken as the research object, through the comparative experimental study of different temperatures and whether warm-mix agent is added, it is found that warm-mix agent can greatly improve the compaction quality of SMA-13 under low temperature conditions, and continuous improvement of warm-mix agent technology provides a strong guarantee for asphalt concrete construction under cold conditions.展开更多
Warm-mix asphalt(WMA) technology was applied for asphalt mixture,plant-produced porous WMA using LEADCAP additive(porous WMA-LEADCAP) test section was built and compacted at 30℃ lower than porous hot-mix asphalt(poro...Warm-mix asphalt(WMA) technology was applied for asphalt mixture,plant-produced porous WMA using LEADCAP additive(porous WMA-LEADCAP) test section was built and compacted at 30℃ lower than porous hot-mix asphalt(porous HMA) test section.Marshall mix designs were conducted for porous WMA-LEADCAP mixture and porous HMA mixture in terms of Marshall stability,Cantabro loss and dynamic stability.The workability,compactablity and surface quality of porous WMA-LEADCAP pavement were investigated,and the engineering properties of plant-produced porous WMA-LEADCAP mixture and plant-produced porous HMA mixture were evaluated based on indirect tensile strength test and dynamic immersion test.Analysis result shows that LEADCAP additive does not affect polymermodified asphalt in terms of penetration,softening point,viscosity,ductility,toughness and tenacity.Porous WMA-LEADCAP pavement has similar field density,permeability and smoothness compared with standard porous HMA pavement.Plant-produced porous WMA-LEADCAP mixture is equivalent to plantproduced porous HMA mixture in indirect tensile strength,toughness and stripping resistance.4tabs,4figs,9refs.展开更多
Within the past two decades or so, the asphalt paving industry has responded positively to increasing global concerns over shrinking natural resource reserves and worsening environmental conditions through the develop...Within the past two decades or so, the asphalt paving industry has responded positively to increasing global concerns over shrinking natural resource reserves and worsening environmental conditions through the development and deployment of warm-mix asphalt technologies. Such technologies make it possible to produce and place asphalt concrete at reduced temperatures compared to conventional hot-mix methods. Several studies have reported on the potential of warm-mix asphalt with regard to improved pavement performance, efficiency and environmental stewardship. This paper reviews several of those studies in the context of pavement sustainability. Overall, warm-mix asphalt provides substantial sustainability benefits similar to or, in some cases, better than conventional hot-mix asphalt. Sustainability benefits include lower energy use, reduced emissions, and potential for increased reclaimed asphalt pavement usage. Growth in utilization of warm-mix asphalt worldwide may, in the not-too-distant future, make the material the standard for asphalt paving. Regardless, there are concerns over some aspects of warm-mix asphalt such as lower resistance to fatigue cracking, rutting and potential water-susceptibility problems, particularly with mixes prepared with water-based technologies, which require further research to address.展开更多
The mixed layer is deep in January-April in the Kuroshio Extension region. This paper investigates the response in this region of mixed layer depth （MLD） and the spring bloom initiation to global warming using the o...The mixed layer is deep in January-April in the Kuroshio Extension region. This paper investigates the response in this region of mixed layer depth （MLD） and the spring bloom initiation to global warming using the output of 15 models from CMIP5. The models indicate that in the late 21st century the mixed layer will shoal and the MLD reduction will be most pronounced in spring at about 33~N on the southern edge of the present deep-MLD region. The advection of temperature change in the upper 100 m by the mean eastward flow explains the spatial pattern of MLD shoaling in the models. Associated with the shoaling mixed layer, the onset of spring bloom inception is projected to advance due to the strengthened stratification in the warming climate.展开更多
Observational data obtained during the TOGA-COARE IOP in the "warm pool" area of the West-ern Tropical Pacific were used to analyze some characteristics of the intraseasonal variations in the mixedlayer. The...Observational data obtained during the TOGA-COARE IOP in the "warm pool" area of the West-ern Tropical Pacific were used to analyze some characteristics of the intraseasonal variations in the mixedlayer. The influence of westerly burst and rainfall on SST, salinity. and mixed layer depth are discussed.There are two pairs of counteracting processes in the "warm pool" mixed layer: (1) The increase of mixedlayer depth caused by local westerly bursts and the decrease of mixed layer depth caused by larger scaleeasterly relaxation;(2) the vertical mixing by local wind and the strong stratification due to rainfall in themixed layer. Some possible mechanisms through the interactions between the intraseasonal time scale varia-tions of the oceanic mixed layer and atmospheric low frequency oscillations are revealed.展开更多
Recycling end-of-life tire rubber as asphalt modifier is known as a sustainable paving technology with merits including enhanced pavement durability,waste tire consumption and noise reduction.However,the criticisms on...Recycling end-of-life tire rubber as asphalt modifier is known as a sustainable paving technology with merits including enhanced pavement durability,waste tire consumption and noise reduction.However,the criticisms on the high construction emissions of asphalt rubber(AR)have limited its application.Warm mix asphalt(WMA)effectively reduces the mixing and compaction temperatures of conventional hot mix asphalt mixtures.The combination of AR and WMA,called warm asphalt rubber(WAR),is a promising paving material which achieves pavement sustainability from principles to practices.Many studies have demonstrated that WMA technologies work effectively with AR pavement in different ways,alleviating the concerns of potential higher emissions of AR by decreasing mixing and paving temperatures.A comprehensive literature review about WAR brings a better understanding of this promising paving technology.The findings of 165 publications were summarized in this review.It summarized the recent developments of WAR in various aspects,including rheological properties,mix design,mixture mechanical performance,field application,construction emission,and asphalt-rubber-WMA additive interaction.It is expected that this review is able to provide extensive information to explore further research development and application of WAR.展开更多
文摘In this paper, the research on warm mix asphalt construction technology of asphalt surface course in low temperature season in cold areas is carried out. The research project is guided by surface theory, mortar theory, strength theory and asphalt concrete regulations, based on solid engineering practice, aiming at breaking through the bottleneck of Asphalt Mixture Construction under low temperature environment, through repeated tests and optimization. Carry out a series of studies including the selection of warm mix agent, the formula, road performance and construction technology of warm mix asphalt mixture, and start from four aspects: the selection of warm mix agent, the proportion and technology of warm mix asphalt mixture, the road performance of warm mix asphalt mixture and the construction technology of warm mix asphalt mixture expressway. It has formed a complete set of technical scheme and control standard system for selecting and determining the optimal type and dosage of warm mix agent, reasonable raw material ratio, mixing process and parameters, road performance and applicability of warm mix asphalt mixture, and construction of warm mix asphalt process in low temperature season of asphalt pavement engineering.
文摘The fatigue behavior, indirect tensile strength （ITS） and resilient modulus test results for warm mix asphalt （WMA） as well as hot mix asphalt （HMA） at different ageing levels were evaluated. Laboratory-prepared samples were aged artificially in the oven to simulate short-term and long term ageing in accordance with AASHTO R30 and then compared with unaged specimens. Beam fatigue testing was performed using beam specimens at 25 ℃ based on AASHTO T321 standard. Fatigue life, bending stiffness and dissipated energy for both unaged and aged mixtures were calculated using four-point beam fatigue test results. Three-point bending tests were performed using semi-circular bend （SCB） specimens at -10 ℃ and the critical mode I stress intensity factor K1 was then calculated using the peak load obtained from the load-displacement curve. It is observed that Sasobit and Rheofalt warm mix asphalt additives have a significant effect on indirect tensile strength, resilient modulus, fatigue behavior and stress intensity factor of aged and unaged mixtures.
文摘In view of the asphalt pavement structure layer dynamic shear creep properties of interface, according to the production mix of warm mix asphalt concrete mixture ratio, and through the European standard wheel rolling compaction machine forming specimen, placed in the mold of the MTS machine related series experiment, temperature, water environment and normal stress factors, to seek the dynamic shear creep displacement along with the changes in the number of cyclic loading. The dynamic creep ability of warm mix asphalt concrete is enhanced with the increase of temperature and water immersion condition. With the increase of normal stress, the displacement of dynamic shear creep in the second stage is relatively large, and the ability of warm mixed asphalt concrete to resist internal shear is enhanced.
文摘With the continuous development of domestic highway construction,highway civil engineering and service level quality have attracted much attention.Good pavement quality and high-quality service make people feel comfortable and smooth when traveling.High-quality pavement can significantly reduce the probability of traffic accidents.At present,there is a direct relationship between pavement quality and pavement construction operations.Carrying out pavement construction operations in cold high-altitude areas requires a reasonable selection of construction equipment and methods.The application of warm-mix asphalt pavement construction technology can ensure pavement quality.Therefore,this paper analyzes the advantages of warm-mix technology,the environmental characteristics of cold high-altitude areas,and construction preparations,and discusses the construction technology of warm-mix asphalt pavement in cold high-altitude areas in detail,to improve the overall road quality of cold high-altitude areas.
基金supported by Funding for Outstanding Doctoral Dissertation in NUAA (BCXJ23-11)Graduate Scientific Research and Innovation Foundation of Chongqing,China(Grant No. CYS20283)Graduate Student Innovative Experiment Competition cultivation program of Nanjing University of Aeronautics and Astronautics.
文摘To achieve environmentally friendly construction and safe operation of tunnel pavements,the mixing construction temperature of asphalt pavements needs to be reduced and the fire safety of asphalt pavements needs to be improved. In this paper, zeolite-based warm mix agent(WMA) and targeted flame retardants(TFR) were used for asphalt modification to reduce the mixing temperature and improve the fire safety of asphalt pavements. First, the formulation of zeolite-based warm mix flame retardant(WMFR) was optimized based on the response surface multi-satisfaction optimization method(RSMOM);then, three kinds of surface modifiers were used to surface modify for WMFR;finally, the functional properties and road performance of WMFR modified asphalt(WMFRMA) were investigated. The results showed that the surface modification could improve the compatibility and storage stability of WMFR with asphalt. The mixing temperature of Titanate coupling agent modified WMFR modified asphalt(Ti-WMFRMA) and surface active agent modified WMFR modified asphalt(Sur-WMFRMA) was reduced by about 10℃ compared with that of the matrix asphalt(JZ). But, there was no significant change in the mixing temperature of Silane coupling agent modified WMFR modified asphalt(Si-WMFRMA). The four kinds of WMFR could effectively improve the fire safety of asphalt binder and mixture. Among them, the peak heat release(PRR) of Sur-WMFRMA was 62.81% lower than that of JZ, and the peak smoke production(PSPR) of Ti-WMFRMA was 69.98% lower than that of JZ. The rheological properties of the flame retardant modified asphalt binder and the road performance of the asphalt mixture were verified, and the surface modification of WMFR could effectively improve the functional properties and road performance of asphalt.
基金the Malaysian Ministry of Higher Education for funding this research through the Exploratory Research Grant Scheme (ERGS grant number 203/ PAWAM/6730111)
文摘Incorporation of warm mix asphalt （WMA） and reclaimed asphalt pavement （RAP） has benefited the asphalt industry in many ways such as reducing the demand for virgin materials, lowering energy requirement during the asphalt production and construction, in addition to reducing greenhouse-gas emissions. This study evaluated the effects of Evotherm and RH-WMA and RAP on mixtures＇ behavior in terms of the compaction energy index （CEI）, indirect tensile strength （ITS） and resilient modulus. The results showed that warm mix additives reduced the CEI, ITS and resilient modulus; while RAP increased the corresponding values. Statistical analysis showed that mixtures incorporating Evotherm and RAP had significant effects on CEI, while the effects of RH-WMA on the corresponding value were found to be statistically insignificant. General Linear Model showed that Evotherm, RAP and RH-WMA exhibited no significant effects on the ITS and resilient modulus. The one-way analysis of variance showed that Evotherm influenced mixture behavior significantly, while RAP and RH-WMA effects were found to be statistically insignificant. Regression equations with high accuracy levels were proposed to predict CEI, ITS and resilient modulus with respect to modification of mixture variables such as mix constituents （Evotherm, RH-WMA, and RAP） and compaction temperature.
文摘This paper presents results from investigating the ageing behaviour and performance of different warm mix asphalt （WMA） pavement mixtures also called energy reduced pavements. The mixtures were either prepared in the laboratory or taken directly from a mixing plant. The study compared the rutting and fatigue behaviours of unaged material in comparison to long term laboratory aged material. In order to conduct the long term ageing, a special laboratory ageing protocol with different heating, cooling and watering cycles had been developed. The investigation revealed a quite controversial rutting behavior which could not be explained with the available data. While most aged energy reduced pavements showed increased rutting for other mixtures, lower rut depths could be found. As opposed to this finding, fatigue and stiffness of all aged energy reduced pave- ment samples compared to unaged samples improved significantly. The overall results led to the conclusion that the ageing of energy reduced pavement simulated in the laboratory is not very critical regarding their mechanical performance. Therefore, it was confrmed that the application of this type of pavement provides a good solution for saving on CO2 emissions. Another advantage is that by using energy reduced pavements the road con- struction season can be significantly prolonged.
基金the financial support of National Natural Science Foundation of China(51378438)National 973 Program(2013CB036204)specific research funding from Ministry of Education(SWJTU12ZT05)
文摘Warm mix asphalt （WMA} is a new technology which asphalt mix is produced and placed at normal temperature. It has advantages including low cost, environmentally friendly, haul-convenience, and so on. WMA has been widely tested and applied in the USA in the last decade, but it has just started in China. Recently, a new WMA using a new plastic- macromolecule-normal temperature additive, which was called ＂SMC＂ by the production company, was introduced as asphalt modifier. Based on discussing the strength forming process of this new WMA with SMC, a series of laboratory tests, including Marshall stability test （MST）, boiling test （BT）, modified immersion Marshall test （MIMT）, freeze-thaw split- ring test （FTST）, rutting test （RT）, low-temperature bending test （LTBT）, and abrasion loss test （ALT）, were conducted in this study to assess the performance of this WMA and the capability of applying it on low volume roads in China. SMC modified asphalt mixed under normal temperature is used in testing samples. It was found that this WMA product exhibited merits on its strength, which was about 6.7 kN bigger than the requirement of 5.0 kN in the JTG F40-2004, on high-temperature stability, which is about 1100 times/ram greater than the requirement of 600-1000 times/mm in the ）TG F40-2004, and on its storage stability. Based on these indicators, it is recommended that this product could be used for low volume low class roads construction. However, due to the relatively lower water resistance and low-temperature cracking resistance, this product is suggested to be applied first in the areas with warm weather and little rainfall. In order to improve the perfor- mance of this WMA with SMC, further research on this SMC asphalt modifier should be continued.
文摘With the continuous improvement of the level of urbanization, the number of road construction is gradually increasing, which greatly facilitates people's travel and promotes the economic development of the city. The quality maintenance of expressway pavement is of great significance to the safety of public traffic. To ensure the service life and quality of expressway, it is extremely important to do a good job of highway maintenance and quality control. Due to the poor maintenance effect of traditional technology and the large exposed base area of highway pavement, this paper analyzes the warm mixing ultra-thin wear layer technology used in the maintenance of expressway, hoping to provide reference for the upgrading of technology in the future.
文摘With the rapid development of municipal engineering, the technology and scheme for the quality control of asphalt pavement concrete are becoming more and more perfect. In order to rush for work and time, paving construction of some asphalt pavements is becoming more and more common in cold winter. In order to ensure the compaction quality of asphalt concrete during construction under low temperature conditions, the application of warm mix is more and more common. In this paper, SMA-13 is taken as the research object, through the comparative experimental study of different temperatures and whether warm-mix agent is added, it is found that warm-mix agent can greatly improve the compaction quality of SMA-13 under low temperature conditions, and continuous improvement of warm-mix agent technology provides a strong guarantee for asphalt concrete construction under cold conditions.
基金Strategic Research Project (Development of Low-Carbon and Low-Cost Asphalt Pavements)Funded by Korea Institute of Construction Technology
文摘Warm-mix asphalt(WMA) technology was applied for asphalt mixture,plant-produced porous WMA using LEADCAP additive(porous WMA-LEADCAP) test section was built and compacted at 30℃ lower than porous hot-mix asphalt(porous HMA) test section.Marshall mix designs were conducted for porous WMA-LEADCAP mixture and porous HMA mixture in terms of Marshall stability,Cantabro loss and dynamic stability.The workability,compactablity and surface quality of porous WMA-LEADCAP pavement were investigated,and the engineering properties of plant-produced porous WMA-LEADCAP mixture and plant-produced porous HMA mixture were evaluated based on indirect tensile strength test and dynamic immersion test.Analysis result shows that LEADCAP additive does not affect polymermodified asphalt in terms of penetration,softening point,viscosity,ductility,toughness and tenacity.Porous WMA-LEADCAP pavement has similar field density,permeability and smoothness compared with standard porous HMA pavement.Plant-produced porous WMA-LEADCAP mixture is equivalent to plantproduced porous HMA mixture in indirect tensile strength,toughness and stripping resistance.4tabs,4figs,9refs.
文摘Within the past two decades or so, the asphalt paving industry has responded positively to increasing global concerns over shrinking natural resource reserves and worsening environmental conditions through the development and deployment of warm-mix asphalt technologies. Such technologies make it possible to produce and place asphalt concrete at reduced temperatures compared to conventional hot-mix methods. Several studies have reported on the potential of warm-mix asphalt with regard to improved pavement performance, efficiency and environmental stewardship. This paper reviews several of those studies in the context of pavement sustainability. Overall, warm-mix asphalt provides substantial sustainability benefits similar to or, in some cases, better than conventional hot-mix asphalt. Sustainability benefits include lower energy use, reduced emissions, and potential for increased reclaimed asphalt pavement usage. Growth in utilization of warm-mix asphalt worldwide may, in the not-too-distant future, make the material the standard for asphalt paving. Regardless, there are concerns over some aspects of warm-mix asphalt such as lower resistance to fatigue cracking, rutting and potential water-susceptibility problems, particularly with mixes prepared with water-based technologies, which require further research to address.
基金supported by the National Basic Research Program of China (Grant No. 2012CB955602)the National Natural Science Foundation of China (Grant Nos. 41476002, 41490643, 41176006 and 41221063)the Fundamental Research Funds for the Central Universities (Grant No. 201503029)
文摘The mixed layer is deep in January-April in the Kuroshio Extension region. This paper investigates the response in this region of mixed layer depth （MLD） and the spring bloom initiation to global warming using the output of 15 models from CMIP5. The models indicate that in the late 21st century the mixed layer will shoal and the MLD reduction will be most pronounced in spring at about 33~N on the southern edge of the present deep-MLD region. The advection of temperature change in the upper 100 m by the mean eastward flow explains the spatial pattern of MLD shoaling in the models. Associated with the shoaling mixed layer, the onset of spring bloom inception is projected to advance due to the strengthened stratification in the warming climate.
基金Supported by National Natural Science Foundation of China (49276250) and LASG of Beijing.
文摘Observational data obtained during the TOGA-COARE IOP in the "warm pool" area of the West-ern Tropical Pacific were used to analyze some characteristics of the intraseasonal variations in the mixedlayer. The influence of westerly burst and rainfall on SST, salinity. and mixed layer depth are discussed.There are two pairs of counteracting processes in the "warm pool" mixed layer: (1) The increase of mixedlayer depth caused by local westerly bursts and the decrease of mixed layer depth caused by larger scaleeasterly relaxation;(2) the vertical mixing by local wind and the strong stratification due to rainfall in themixed layer. Some possible mechanisms through the interactions between the intraseasonal time scale varia-tions of the oceanic mixed layer and atmospheric low frequency oscillations are revealed.
基金Project(51808228)supported by the National Natural Science Foundation of ChinaProject(OE514/10-1)supported by the German Research Foundation。
文摘Recycling end-of-life tire rubber as asphalt modifier is known as a sustainable paving technology with merits including enhanced pavement durability,waste tire consumption and noise reduction.However,the criticisms on the high construction emissions of asphalt rubber(AR)have limited its application.Warm mix asphalt(WMA)effectively reduces the mixing and compaction temperatures of conventional hot mix asphalt mixtures.The combination of AR and WMA,called warm asphalt rubber(WAR),is a promising paving material which achieves pavement sustainability from principles to practices.Many studies have demonstrated that WMA technologies work effectively with AR pavement in different ways,alleviating the concerns of potential higher emissions of AR by decreasing mixing and paving temperatures.A comprehensive literature review about WAR brings a better understanding of this promising paving technology.The findings of 165 publications were summarized in this review.It summarized the recent developments of WAR in various aspects,including rheological properties,mix design,mixture mechanical performance,field application,construction emission,and asphalt-rubber-WMA additive interaction.It is expected that this review is able to provide extensive information to explore further research development and application of WAR.
