High temperature rutting is a typical highway damage in Xinjiang, China, and its trigger process usually has a close relationship with characteristics of road temperature distribution. A numerical model of earth-atmos...High temperature rutting is a typical highway damage in Xinjiang, China, and its trigger process usually has a close relationship with characteristics of road temperature distribution. A numerical model of earth-atmosphere coupling heat transfer on a typical section of the Beijing-Xinjiang Expressway(G7) from Wutong Daquan to Yiwu was established in this work. Spatiotemporal characteristics of pavement structure layer temperature distribution, frequency and duration times of road surface high temperature from May 1 to September 30 are statistically studied. The effects of wind speed, weather and air temperature on asphalt layer and pavement temperature are analyzed. The results show that:(1) Spatial and temporal temperature distribution characteristics of pavement structural layers are greatly affected by the coupled earth-atmosphere heat transfer process. Surface temperature increases along the airflow direction and daily temperature variation of the pavement structure layer decreases with an increase of depth.(2) G7 expressway will face the challenge of high rutting damage. The proportion of temperature higher than 50 ℃ for pavement surface and asphalt upper layer both exceeds 50%and high temperature of road lasts for more than six hours in numerous days.(3) High temperatures of asphalt pavement are usually associated with low ambient wind speeds, while the wind flow has little cooling effect when the road surface temperature is relative high. Weather conditions have a significant impact on temperature of the road surface. The probability of high temperature in sunny days is obviously higher than other weather conditions.(4) Pavement temperature rises as air temperature rises. When air temperature is higher than 30 °C, the proportion of pavement daily maximum temperature over softening point reaches up to 78%.展开更多
Superhydrophobic materials are severely limited in their applications due to their weak mechanical properties and complex preparation process.In this paper,polystyrene/fluorinated silica(PS/SiO_(2))superhydrophobic co...Superhydrophobic materials are severely limited in their applications due to their weak mechanical properties and complex preparation process.In this paper,polystyrene/fluorinated silica(PS/SiO_(2))superhydrophobic composite coatings were prepared on the surface of 304 stainless steel using a simple one-step spraying method.The effects of different PS contents on the wettability as well as the wear properties of the samples were investigated.SiO_(2) was encapsulated in polystyrene to form a structure similar to cement encapsulated stones.With the addition of PS,a mound-like structure was formed on the sample surface,and a more optimized micro–nano structure was obtained when the content of PS was 0.6 g.At this time,the sample exhibited excellent wettability with a contact angle of 157.86°and a sliding angle of 0.84°.In addition,the contact angle of 151.09°was achieved after 180 cm of friction under a 100 g load and the composite coating prepared by this method also has excellent chemical stability,water impact resistance,corrosion resistance,and self-cleaning properties.This opens up new possibilities for the development of simple and robust superhydrophobic materials.展开更多
基金supported by the China Railway Construction Group Scientific Research and Development Project(ZTJ2021WBXKYKT)Natural Science Foundation of Shaanxi Province(Grant No.2022JM143)+1 种基金the Fundamental Research Funds for the Central Universities,CHD(Grant No.300102262104)the National Science Foundation of China(Grant Nos.41502292,51574037)。
文摘High temperature rutting is a typical highway damage in Xinjiang, China, and its trigger process usually has a close relationship with characteristics of road temperature distribution. A numerical model of earth-atmosphere coupling heat transfer on a typical section of the Beijing-Xinjiang Expressway(G7) from Wutong Daquan to Yiwu was established in this work. Spatiotemporal characteristics of pavement structure layer temperature distribution, frequency and duration times of road surface high temperature from May 1 to September 30 are statistically studied. The effects of wind speed, weather and air temperature on asphalt layer and pavement temperature are analyzed. The results show that:(1) Spatial and temporal temperature distribution characteristics of pavement structural layers are greatly affected by the coupled earth-atmosphere heat transfer process. Surface temperature increases along the airflow direction and daily temperature variation of the pavement structure layer decreases with an increase of depth.(2) G7 expressway will face the challenge of high rutting damage. The proportion of temperature higher than 50 ℃ for pavement surface and asphalt upper layer both exceeds 50%and high temperature of road lasts for more than six hours in numerous days.(3) High temperatures of asphalt pavement are usually associated with low ambient wind speeds, while the wind flow has little cooling effect when the road surface temperature is relative high. Weather conditions have a significant impact on temperature of the road surface. The probability of high temperature in sunny days is obviously higher than other weather conditions.(4) Pavement temperature rises as air temperature rises. When air temperature is higher than 30 °C, the proportion of pavement daily maximum temperature over softening point reaches up to 78%.
基金This study was supported by the National Natural Science Foundation of China(Grant Number 52172090 and 52071159).
文摘Superhydrophobic materials are severely limited in their applications due to their weak mechanical properties and complex preparation process.In this paper,polystyrene/fluorinated silica(PS/SiO_(2))superhydrophobic composite coatings were prepared on the surface of 304 stainless steel using a simple one-step spraying method.The effects of different PS contents on the wettability as well as the wear properties of the samples were investigated.SiO_(2) was encapsulated in polystyrene to form a structure similar to cement encapsulated stones.With the addition of PS,a mound-like structure was formed on the sample surface,and a more optimized micro–nano structure was obtained when the content of PS was 0.6 g.At this time,the sample exhibited excellent wettability with a contact angle of 157.86°and a sliding angle of 0.84°.In addition,the contact angle of 151.09°was achieved after 180 cm of friction under a 100 g load and the composite coating prepared by this method also has excellent chemical stability,water impact resistance,corrosion resistance,and self-cleaning properties.This opens up new possibilities for the development of simple and robust superhydrophobic materials.
