This paper presents a method to characterize asphalt pavement macrotexture using the gray-tone difference matrix （GTDM）and discusses the potentials of the GTDM indicators for skid resistance evaluation.There are 37 ...This paper presents a method to characterize asphalt pavement macrotexture using the gray-tone difference matrix （GTDM）and discusses the potentials of the GTDM indicators for skid resistance evaluation.There are 37 field sites included in the data collection,which cover 6 types of asphalt pavement surfaces. The mean profile depth derived from 3-D macrotexture measurements （MPD3 ） has a significant relationship with the mean texture depth （MTD ）,which can be described by a logarithm model with R2 of 0.962.There is no significant linear relationship between the friction coefficient at a speed of 60 km/h （DFT60 ）and macrotexture indicators.A nonlinear model with British pendulum number （BPN ） incorporated can relate DFT60 to MTD or indicator fcon .A comparison with MTD shows that GTDM-based fcon has a potential to be a macrotexture indicator for skid resistance evaluation,which describes the general height difference and the average local height difference of pavement macrotexture. A relatively high fcon is helpful for improving asphalt pavement skid resistance.展开更多
Twin roll cast ZK60 alloy strip/sheet with final thickness of 0.5 mm was prepared, and effect of rolling temperature on microstructure and texture development was investigated using OM and XRD technique, microstructur...Twin roll cast ZK60 alloy strip/sheet with final thickness of 0.5 mm was prepared, and effect of rolling temperature on microstructure and texture development was investigated using OM and XRD technique, microstructure and texture were measured on specimens subjected to rolling experiment at different rolling temperature, and macrotexture was also evaluated by X-ray diffraction method. In addition, the （1010）and （0002） pole figures were measured, and the tensile test was performed to reveal the influence of rolling temperature on mechanical properties. The results show that the microstrucmre of ZK60 alloy sheet consisted of fibrous structure with elongated grains, and shear bands along the rolling direction after warm rolling. Dynamic recrystallization could be found during the warm rolling process at rolling temperature 350℃ and above. And many fine recrystallized grain could be observed in the shear bands area. It is a little difficult to see the recrystallized grain in the sheet warm rolled at 300℃ because of higher density of shear bands. The warm rolled ZK60 alloy sheet exhibited strong （0002） pole texture, the intensity of （0002） pole figure decreases with the increasing of rolling temperature and the basal pole tilted slightly to the transverse direction after warm rolling.展开更多
This study entailed an investigation of the mechanical properties,microstructural and texture orientation evolutions of Cu-Cr-Co-Ti alloys prepared via twostage cryorolling and intermediate aging treatment.To this end...This study entailed an investigation of the mechanical properties,microstructural and texture orientation evolutions of Cu-Cr-Co-Ti alloys prepared via twostage cryorolling and intermediate aging treatment.To this end,X-ray diffraction and electron backscatter diffraction were employed.The results indicate that the two-stage cryorolling and intermediate aging treatments led to the development of profuse twin bundles and significantly enhanced the mechanical properties.The initial cryorolling led to coplanar slip and developed a strong Y({111}<112>)orientation,accelerating the formation of Goss({011}<100>)orientation and a Brass-type texture.The intermediate aging treatment relieved the restriction on dislocation slip and reoriented the grains toward the Copper({112}<111>)and Z({111}<110>)orientations.The Z orientation,with a relatively high volume fraction,dominated the macrotexture.Secondary cryorolling intensified twinning and shear banding,transforming the Copper-type shear bands into Brass-type shear bands with rhomboidal prism morphology.The areas inside the Brasstype shear bands exhibited a Y orientation,and the areas outside the shear bands exhibited a stable Brass-type texture.The evident decrease in the weighted Schmid factors demonstrated that the two-stage cryorolling and intermediate aging treatment can modify the texture evolution and aid the design of high-performance Cu alloys.展开更多
Adequate pavement skid resistance is a key requirement for safe road operations.Unfortunately,the measurement and prediction of the skid resistance property of an in-service road pavement,or pavement mixture specimens...Adequate pavement skid resistance is a key requirement for safe road operations.Unfortunately,the measurement and prediction of the skid resistance property of an in-service road pavement,or pavement mixture specimens in the laboratory,is a highly challenging process from both theoretical and practical points of view.For more than 60 years,owing to the lack of theoretical solutions to the complex tire-fluid-pavement interaction problem,the practice of pavement skid resistance determination and prediction has essentially been derived from experimental and field observed data.The rapid development of efficient numerical computational techniques and high-power computing facilities in the last two decades made it possible for researchers to numerically solve the tire-fluidpavement interaction problem.It enables the numerical evaluation and prediction of high-speed wet skid resistance,and the determination of the tire-pavement kinetic friction coefficient in the evaluation of low-speed skid resistance.This paper presents a state-of-the-art review of the research development of theoretical mechanistic approaches in the determination and prediction of pavement skid resistance.It covers the following main aspects of the subject matter:(i)mechanisms of skid resistance generation in dry,wetted(i.e.,damp),wet and flooded pavements;(ii)theoretical evaluation of pavement skid resistance in dry,wetted,wet and flooded states;(iii)theoretical approaches in pavement skid resistance prediction;and(iv)concepts of representing the skid resistance state of pavement.The capability of finite element simulation approach for wet skid resistance evaluation with good accuracy is explained.Also highlighted is the practical significance of the Concept of Skid Resistance State.Areas of practical applications of the concept,coupled with the simulation model,are introduced.They include applications in driving safety analysis,road safety design and control,design of paving mixtures,safety maintenance and management of pavements,and harmonization of skid resistance measurements and predictions.展开更多
Skid resistance of road surface plays an important role on urban traffic accidents. It is thought that reduction of surface microtexture leads to reduced skid resistance. Hence, it affects driving safety negatively an...Skid resistance of road surface plays an important role on urban traffic accidents. It is thought that reduction of surface microtexture leads to reduced skid resistance. Hence, it affects driving safety negatively and may cause traffic accidents, This paper is about the effect of skid resistance and intersection safety. Urban four leg signalized intersections were selected from Isparta city. The surface frictional properties were measured and it was tried to find critical skid resistance value with the help of British Pendulum Tester. Macro texture values of the intersections were determined with Sand Patch test and concluded that surface macro texture contributes to skid resistance. An analysis technique based on probabili theory has been used. This method is used for expounding the interaction between skid resistance-intersection and accident rates. After the study results are evaluated, it is understood that pavement roughness is very important for urban intersection safety measures.展开更多
Recently, diamond grinding has gained increasing attention as pavement preservation treatment to restore desired surface characteristics, particularly friction. Compared to other pavement preservation treatments such ...Recently, diamond grinding has gained increasing attention as pavement preservation treatment to restore desired surface characteristics, particularly friction. Compared to other pavement preservation treatments such as surface overlays and high friction surface treat- ments, diamond grinding may cost less, save construction time, or require minimum maintenance. Diamond grinding produces longitudinal, continuous, and line-type texture that contains corrugations with evenly spaced ridges. The improved surface texture will immediately enhance pavement surface friction and reduce the possibility of hydroplaning in rainy weather. However, little information has been documented on the texture charac- teristics and long-term friction performance of diamond-ground pavements. A field evalu- ation was conducted to examine the surface texture and friction characteristics in diamond- ground concrete and asphalt pavements by the authors. Five pavement test sections, including two diamond-ground concrete pavements, one diamond-ground concrete bridge deck, one diamond-ground asphalt pavement, and one transversely tined concrete pave- ment, were selected for evaluation. Laser scanner testing was performed to capture both macro and microtexture profiles. Locked wheel testing was performed to measure the fric- tion numbers. The test results were examined and compared so as to evaluate two performances, after construction and long-term friction performance of diamond-ground pavements. It was found that longitudinal diamond grinding can provide durable, satisfactory surface friction performance for both concrete and asphalt pavements.展开更多
Porous asphalts have supplementary surface and volumetric properties(e.g., acoustic absorption, drain ability, texture, and friction). These properties are linked to intrinsic factors(e.g., gradation and bitumen conte...Porous asphalts have supplementary surface and volumetric properties(e.g., acoustic absorption, drain ability, texture, and friction). These properties are linked to intrinsic factors(e.g., gradation and bitumen content) and extrinsic factors(e.g., traffic load), while their evolution over time depends on complex phenomena and processes that cause their deterioration and therefore affect safety, noise, and budget. Despite the decay of so many and complex properties over time, there is a lack of criteria to synergistically optimize the pavement system. Consequently, the objective of this study is to set up and validate a design method that synergistically addresses the most relevant properties of friction courses as a part of a pavement structure. The abovementioned method is based on indepth analyses of the literature and on laboratory and on-site tests carried for several years in order to evaluate the decay over time of the main surface and volumetric properties.Results show that (1) the level of fulfilment of single requirements varies over time and among the characteristics;(2) a sound optimization of the design of the mix in order to balance the different characteristics is needed;(3) further studies are needed because of uncertainty in predicting the main surface properties.展开更多
基金The National Natural Science Foundation of China(No.50908004,51178013)
文摘This paper presents a method to characterize asphalt pavement macrotexture using the gray-tone difference matrix （GTDM）and discusses the potentials of the GTDM indicators for skid resistance evaluation.There are 37 field sites included in the data collection,which cover 6 types of asphalt pavement surfaces. The mean profile depth derived from 3-D macrotexture measurements （MPD3 ） has a significant relationship with the mean texture depth （MTD ）,which can be described by a logarithm model with R2 of 0.962.There is no significant linear relationship between the friction coefficient at a speed of 60 km/h （DFT60 ）and macrotexture indicators.A nonlinear model with British pendulum number （BPN ） incorporated can relate DFT60 to MTD or indicator fcon .A comparison with MTD shows that GTDM-based fcon has a potential to be a macrotexture indicator for skid resistance evaluation,which describes the general height difference and the average local height difference of pavement macrotexture. A relatively high fcon is helpful for improving asphalt pavement skid resistance.
基金Project(35060905) supported by the Doctoral Foundation of Jiangsu University of Science and Technology
文摘Twin roll cast ZK60 alloy strip/sheet with final thickness of 0.5 mm was prepared, and effect of rolling temperature on microstructure and texture development was investigated using OM and XRD technique, microstructure and texture were measured on specimens subjected to rolling experiment at different rolling temperature, and macrotexture was also evaluated by X-ray diffraction method. In addition, the （1010）and （0002） pole figures were measured, and the tensile test was performed to reveal the influence of rolling temperature on mechanical properties. The results show that the microstrucmre of ZK60 alloy sheet consisted of fibrous structure with elongated grains, and shear bands along the rolling direction after warm rolling. Dynamic recrystallization could be found during the warm rolling process at rolling temperature 350℃ and above. And many fine recrystallized grain could be observed in the shear bands area. It is a little difficult to see the recrystallized grain in the sheet warm rolled at 300℃ because of higher density of shear bands. The warm rolled ZK60 alloy sheet exhibited strong （0002） pole texture, the intensity of （0002） pole figure decreases with the increasing of rolling temperature and the basal pole tilted slightly to the transverse direction after warm rolling.
基金supported by the National Natural Science Foundation of China(Nos.52271025,51927801 and U22A20174)the Science and Technology Planning Project of Liaoning Province(No.2023JH2/101700295)+1 种基金the Innovation Foundation of Science and the Technology of Dalian(No.2023JJ12GX021)the Natural Science Foundation of Jiangsu Province(No.BK20200695)。
文摘This study entailed an investigation of the mechanical properties,microstructural and texture orientation evolutions of Cu-Cr-Co-Ti alloys prepared via twostage cryorolling and intermediate aging treatment.To this end,X-ray diffraction and electron backscatter diffraction were employed.The results indicate that the two-stage cryorolling and intermediate aging treatments led to the development of profuse twin bundles and significantly enhanced the mechanical properties.The initial cryorolling led to coplanar slip and developed a strong Y({111}<112>)orientation,accelerating the formation of Goss({011}<100>)orientation and a Brass-type texture.The intermediate aging treatment relieved the restriction on dislocation slip and reoriented the grains toward the Copper({112}<111>)and Z({111}<110>)orientations.The Z orientation,with a relatively high volume fraction,dominated the macrotexture.Secondary cryorolling intensified twinning and shear banding,transforming the Copper-type shear bands into Brass-type shear bands with rhomboidal prism morphology.The areas inside the Brasstype shear bands exhibited a Y orientation,and the areas outside the shear bands exhibited a stable Brass-type texture.The evident decrease in the weighted Schmid factors demonstrated that the two-stage cryorolling and intermediate aging treatment can modify the texture evolution and aid the design of high-performance Cu alloys.
文摘Adequate pavement skid resistance is a key requirement for safe road operations.Unfortunately,the measurement and prediction of the skid resistance property of an in-service road pavement,or pavement mixture specimens in the laboratory,is a highly challenging process from both theoretical and practical points of view.For more than 60 years,owing to the lack of theoretical solutions to the complex tire-fluid-pavement interaction problem,the practice of pavement skid resistance determination and prediction has essentially been derived from experimental and field observed data.The rapid development of efficient numerical computational techniques and high-power computing facilities in the last two decades made it possible for researchers to numerically solve the tire-fluidpavement interaction problem.It enables the numerical evaluation and prediction of high-speed wet skid resistance,and the determination of the tire-pavement kinetic friction coefficient in the evaluation of low-speed skid resistance.This paper presents a state-of-the-art review of the research development of theoretical mechanistic approaches in the determination and prediction of pavement skid resistance.It covers the following main aspects of the subject matter:(i)mechanisms of skid resistance generation in dry,wetted(i.e.,damp),wet and flooded pavements;(ii)theoretical evaluation of pavement skid resistance in dry,wetted,wet and flooded states;(iii)theoretical approaches in pavement skid resistance prediction;and(iv)concepts of representing the skid resistance state of pavement.The capability of finite element simulation approach for wet skid resistance evaluation with good accuracy is explained.Also highlighted is the practical significance of the Concept of Skid Resistance State.Areas of practical applications of the concept,coupled with the simulation model,are introduced.They include applications in driving safety analysis,road safety design and control,design of paving mixtures,safety maintenance and management of pavements,and harmonization of skid resistance measurements and predictions.
文摘Skid resistance of road surface plays an important role on urban traffic accidents. It is thought that reduction of surface microtexture leads to reduced skid resistance. Hence, it affects driving safety negatively and may cause traffic accidents, This paper is about the effect of skid resistance and intersection safety. Urban four leg signalized intersections were selected from Isparta city. The surface frictional properties were measured and it was tried to find critical skid resistance value with the help of British Pendulum Tester. Macro texture values of the intersections were determined with Sand Patch test and concluded that surface macro texture contributes to skid resistance. An analysis technique based on probabili theory has been used. This method is used for expounding the interaction between skid resistance-intersection and accident rates. After the study results are evaluated, it is understood that pavement roughness is very important for urban intersection safety measures.
文摘Recently, diamond grinding has gained increasing attention as pavement preservation treatment to restore desired surface characteristics, particularly friction. Compared to other pavement preservation treatments such as surface overlays and high friction surface treat- ments, diamond grinding may cost less, save construction time, or require minimum maintenance. Diamond grinding produces longitudinal, continuous, and line-type texture that contains corrugations with evenly spaced ridges. The improved surface texture will immediately enhance pavement surface friction and reduce the possibility of hydroplaning in rainy weather. However, little information has been documented on the texture charac- teristics and long-term friction performance of diamond-ground pavements. A field evalu- ation was conducted to examine the surface texture and friction characteristics in diamond- ground concrete and asphalt pavements by the authors. Five pavement test sections, including two diamond-ground concrete pavements, one diamond-ground concrete bridge deck, one diamond-ground asphalt pavement, and one transversely tined concrete pave- ment, were selected for evaluation. Laser scanner testing was performed to capture both macro and microtexture profiles. Locked wheel testing was performed to measure the fric- tion numbers. The test results were examined and compared so as to evaluate two performances, after construction and long-term friction performance of diamond-ground pavements. It was found that longitudinal diamond grinding can provide durable, satisfactory surface friction performance for both concrete and asphalt pavements.
文摘Porous asphalts have supplementary surface and volumetric properties(e.g., acoustic absorption, drain ability, texture, and friction). These properties are linked to intrinsic factors(e.g., gradation and bitumen content) and extrinsic factors(e.g., traffic load), while their evolution over time depends on complex phenomena and processes that cause their deterioration and therefore affect safety, noise, and budget. Despite the decay of so many and complex properties over time, there is a lack of criteria to synergistically optimize the pavement system. Consequently, the objective of this study is to set up and validate a design method that synergistically addresses the most relevant properties of friction courses as a part of a pavement structure. The abovementioned method is based on indepth analyses of the literature and on laboratory and on-site tests carried for several years in order to evaluate the decay over time of the main surface and volumetric properties.Results show that (1) the level of fulfilment of single requirements varies over time and among the characteristics;(2) a sound optimization of the design of the mix in order to balance the different characteristics is needed;(3) further studies are needed because of uncertainty in predicting the main surface properties.
