Asphalt binder is inevitably aged by ultraviolet(UV)light during its service period.UV ageing can significantly decrease the technical properties of asphalt binder.The sensitivity of asphalt to UV ageing and thermal-o...Asphalt binder is inevitably aged by ultraviolet(UV)light during its service period.UV ageing can significantly decrease the technical properties of asphalt binder.The sensitivity of asphalt to UV ageing and thermal-oxidative ageing differs,such that the UV ageing performance cannot be determined based on the thermal-oxidative ageing performance.Previous researches mainly focused on the chemical composite and technical performance changes of asphalt binder during UV ageing,and the UV light parameters effect on the ageing rate of asphalt binder.However,the theory for characterizing and explaining the development of UV ageing depth does not get too much attentions,and the UV ageing mechanism of asphalt binder is not very clear.Therefore,it cannot guide to develop or select the good methods or anti-UV ageing additives for asphalt binders.This paper focuses on the latest researches of the mechanisms and anti-ageing methods of asphalt binders.With the increase of UV ageing time,the UV ageing of asphalt binder develops gradually from the surface to inner part.There are various methods,such as low-penetration grade asphalt,less air void ratio,UV stabilizers and UV light absorbers,that can improve the UV ageing resistance of asphalt binders.A new theory of sensitive wavelengths of asphalt UV ageing is proposed,which can enrich the basic theory of asphalt UV ageing.Depending on this theory,different wavelengths of UV light have different ageing effects on asphalt binder.The composite anti-UV ageing additives with barrier and specific absorption effects on UV light is proposed,and may have better improvement effect on the anti-UV ageing performance of asphalt binder.展开更多
Old-age dependency ratio(OADR)is commonly used to indicate the financial burden of population aging;increases in OADR have caused widespread concerns.To better measure the financial burden,this paper proposes a depend...Old-age dependency ratio(OADR)is commonly used to indicate the financial burden of population aging;increases in OADR have caused widespread concerns.To better measure the financial burden,this paper proposes a dependency ratio of non-labor-force population to labor-force population(NLDR).This ratio includes OADR as a special case.This paper finds that,when measured by NLDR,financial burden actually declined in five of the G7 countries during the years 2000-2014.To project future trends,labor force participation rates by age f(x)can be forecasted using the coherent LeeCarter method.This paper combines the forecasted f(x)and the population projections of the United Nations,to forecast increases of NLDR for the G7 countries between 2014 and 2050.These increases are on average less than onefifth of the increases projected for OADR.Because OADR ignores the increase of labor force participation,its description of the problem of population aging for the G7 countries in the past is unrealistic and inaccurate,and forecasts of the future based on OADR are likely to be just as unrealistic.Understanding the conditions and reasons for increases in labor force participation can provide valuable insights into the issues of population aging in China,where the remarkable increase of OADR may result in real financial burdens.One condition for labor force participation to increase could be that people remain in good health,which makes continuing to work more feasible.Other reasons for labor force participation to increase are likely to be found in government policies that encourage people to continue working longer.For China,collecting reliable data on labor force participation is also crucial.Without these data,the effects of the policies that encourage people to continue working longer cannot be detected;and therefore the policies cannot be properly developed.展开更多
基金The authors acknowledge the financial supported by National Natural Science Foundation of China(No.52108415 and No.51808517)the National Key R&D Program of China(No.2018YFB1600200)+5 种基金the Key Technical Innovation Projects of Hubei Province(No.2019AEE023)the Key R&D Program of Hubei Province(No.2020BCB064)the State Key Laboratory of Silicate Materials for Architectures(Wuhan University of Technology)(No.SYSJJ2022-21),the Transportation Technology Project of Department of Transport of Hubei Province(No.2022-11-1-10)the European Union's Horizon 2020 Research and Innovation Programme Under the Marie Skłodowska-Curie Grant Agreement(No.101030767)the Scientific Research Fund Project of Wuhan Institute of Technology(No.K2021032)the Open Fund of National&Local Joint Engineering Laboratory of Traffic Civil Engineering Materials,Chongqing Jiaotong University(No.LHSYS-2020-004).
文摘Asphalt binder is inevitably aged by ultraviolet(UV)light during its service period.UV ageing can significantly decrease the technical properties of asphalt binder.The sensitivity of asphalt to UV ageing and thermal-oxidative ageing differs,such that the UV ageing performance cannot be determined based on the thermal-oxidative ageing performance.Previous researches mainly focused on the chemical composite and technical performance changes of asphalt binder during UV ageing,and the UV light parameters effect on the ageing rate of asphalt binder.However,the theory for characterizing and explaining the development of UV ageing depth does not get too much attentions,and the UV ageing mechanism of asphalt binder is not very clear.Therefore,it cannot guide to develop or select the good methods or anti-UV ageing additives for asphalt binders.This paper focuses on the latest researches of the mechanisms and anti-ageing methods of asphalt binders.With the increase of UV ageing time,the UV ageing of asphalt binder develops gradually from the surface to inner part.There are various methods,such as low-penetration grade asphalt,less air void ratio,UV stabilizers and UV light absorbers,that can improve the UV ageing resistance of asphalt binders.A new theory of sensitive wavelengths of asphalt UV ageing is proposed,which can enrich the basic theory of asphalt UV ageing.Depending on this theory,different wavelengths of UV light have different ageing effects on asphalt binder.The composite anti-UV ageing additives with barrier and specific absorption effects on UV light is proposed,and may have better improvement effect on the anti-UV ageing performance of asphalt binder.
文摘Old-age dependency ratio(OADR)is commonly used to indicate the financial burden of population aging;increases in OADR have caused widespread concerns.To better measure the financial burden,this paper proposes a dependency ratio of non-labor-force population to labor-force population(NLDR).This ratio includes OADR as a special case.This paper finds that,when measured by NLDR,financial burden actually declined in five of the G7 countries during the years 2000-2014.To project future trends,labor force participation rates by age f(x)can be forecasted using the coherent LeeCarter method.This paper combines the forecasted f(x)and the population projections of the United Nations,to forecast increases of NLDR for the G7 countries between 2014 and 2050.These increases are on average less than onefifth of the increases projected for OADR.Because OADR ignores the increase of labor force participation,its description of the problem of population aging for the G7 countries in the past is unrealistic and inaccurate,and forecasts of the future based on OADR are likely to be just as unrealistic.Understanding the conditions and reasons for increases in labor force participation can provide valuable insights into the issues of population aging in China,where the remarkable increase of OADR may result in real financial burdens.One condition for labor force participation to increase could be that people remain in good health,which makes continuing to work more feasible.Other reasons for labor force participation to increase are likely to be found in government policies that encourage people to continue working longer.For China,collecting reliable data on labor force participation is also crucial.Without these data,the effects of the policies that encourage people to continue working longer cannot be detected;and therefore the policies cannot be properly developed.
