The research on asphalt performance mainly focused on the macro performance and micro mechanism.Mesoscopic analysis was introduced to study the effect of rubber powder movement on asphalt rubber properties.After the p...The research on asphalt performance mainly focused on the macro performance and micro mechanism.Mesoscopic analysis was introduced to study the effect of rubber powder movement on asphalt rubber properties.After the preparation parameters and the preparation process of asphalt rubber were determined,the modification mechanism and rheological properties were analyzed which revealed the compatible stability mechanism.Then,the analysis model of asphalt rubber was established to focus on simulating the effect of rubber powder and the spatial movement on its mechanical properties.The experimental results show that rubber powder can make the asphalt rubber bear more uniform stress distribution and enhance the ability to resist deformation.Meanwhile,the rotational motion and final distribution of rubber powder have an obvious impact on the mechanical properties of asphalt rubber.In the selected feature points,the average stress of rubber powder at 0°space angle is only 34.1%of that at90°space angle.When the rubber powders are all in parallel in the ideal state,it enhances the mechanical properties the most.This study supplements the“mesoscopic”scale between macro and micro research.The relationship between micro mechanism and macro properties of asphalt rubber will be established from the mesoscopic perspective.It is also an effort to realize the effective correlation from micro,mesoscopic to macro in asphalt.展开更多
A dynamic triaxial instrument was used to study the effects of different concentrations of sodium chloride and stress amplitudes on the dynamic properties of an expansive soil under cyclic loading.In particular,four p...A dynamic triaxial instrument was used to study the effects of different concentrations of sodium chloride and stress amplitudes on the dynamic properties of an expansive soil under cyclic loading.In particular,four parameters were considered in such a parametric investigation,namely,hysteresis curve morphology characteristic non-closure degreeεp,the ratio of the short and long axisα,the slope of the long axis k and the enclosed area S.The results show that with an increase in the sodium chloride concentration,the soil particle double electric layer becomes thinner,the distance between soil particles decreases,and the whole sample becomes denser.Theεp-N,α-N and S–N relation curves all show a decreasing trend.The ratio of plastic deformation to total deformation grows with increasing the dynamic stress amplitude,and the curves show an upwards trend.The k-N relationship curve displays an increasing trend with the concentration and a general downwards trend as the dynamic stress amplitude is made higher.This also indicates that sodium chloride solutions can improve the engineering properties of expansive soil to a certain extent.With an increase in the vibration times N,the shape of the hysteretic curve becomes narrower,and the whole soil exhibits a cyclic strain hardening.With the help of an exponential function,a model is introduced to predict the relationship between the concentration and the hysteretic curve.展开更多
Waste plastics and rubber have always posed a threat to the environment and a great challenge for disposal.The use of these two waste materials as modifiers for road asphalt provides new road asphalt binders and at th...Waste plastics and rubber have always posed a threat to the environment and a great challenge for disposal.The use of these two waste materials as modifiers for road asphalt provides new road asphalt binders and at the same time provides a new way for waste material resource treatment.Rubber-modified asphalt and plastic-modified asphalt have received widespread attention due to their green and low-carbon characteristics and some performance advantages,but there are still some performance shortcomings that hinder their promotion and application.In order to continue to explore the application of waste materials in the field of road engineering,combined with the performance advantages of both,many scholars began to study the rubber-plastic composite modified asphalt(RPCMA).Therefore,this paper reviewed the different types of waste rubber and plastic,the comprehensive performance of different types of asphalt and its mixture performance,analyzed the modification mechanism of rubber-plastic composite modified asphalt and its performance changes.The results show that rubber-plastic composite modified asphalt is mostly prepared by directly adding modified materials.However,the pretreatment or melt granulation of rubber and plastic will make the performance of rubber-plastic modified asphalt has improved.There is a mutual promotion mechanism between rubber and plastic in asphalt,which makes the performance of rubber-plastic modified asphalt better than that of asphalt obtained by a single modification method(rubber modified asphalt or plastic modified asphalt).In some properties,it can be close to the commercial SBS modified asphalt.The performance of rubber and plastic composite modified asphalt at high temperature has been generally recognized by researchers,but its low-temperature performance is still controversial.Therefore,it is recommended to apply in high-temperature areas.Future work should focus on the development of composite modifiers with stable performance,low cost and ease of use,standardization of modification processes,improvement of low-temperature performance,and monitoring of road performance and environmental impact.展开更多
基金Funded by the Key Research and Development Projects in Shaanxi Province (2022SF-328)the Science and Technology Project of Henan Department of Transportation (2020J-2-3)the Science and Technology Project of Shaanxi Department of Transportation (Nos.19-10K and 19-28K)。
文摘The research on asphalt performance mainly focused on the macro performance and micro mechanism.Mesoscopic analysis was introduced to study the effect of rubber powder movement on asphalt rubber properties.After the preparation parameters and the preparation process of asphalt rubber were determined,the modification mechanism and rheological properties were analyzed which revealed the compatible stability mechanism.Then,the analysis model of asphalt rubber was established to focus on simulating the effect of rubber powder and the spatial movement on its mechanical properties.The experimental results show that rubber powder can make the asphalt rubber bear more uniform stress distribution and enhance the ability to resist deformation.Meanwhile,the rotational motion and final distribution of rubber powder have an obvious impact on the mechanical properties of asphalt rubber.In the selected feature points,the average stress of rubber powder at 0°space angle is only 34.1%of that at90°space angle.When the rubber powders are all in parallel in the ideal state,it enhances the mechanical properties the most.This study supplements the“mesoscopic”scale between macro and micro research.The relationship between micro mechanism and macro properties of asphalt rubber will be established from the mesoscopic perspective.It is also an effort to realize the effective correlation from micro,mesoscopic to macro in asphalt.
文摘A dynamic triaxial instrument was used to study the effects of different concentrations of sodium chloride and stress amplitudes on the dynamic properties of an expansive soil under cyclic loading.In particular,four parameters were considered in such a parametric investigation,namely,hysteresis curve morphology characteristic non-closure degreeεp,the ratio of the short and long axisα,the slope of the long axis k and the enclosed area S.The results show that with an increase in the sodium chloride concentration,the soil particle double electric layer becomes thinner,the distance between soil particles decreases,and the whole sample becomes denser.Theεp-N,α-N and S–N relation curves all show a decreasing trend.The ratio of plastic deformation to total deformation grows with increasing the dynamic stress amplitude,and the curves show an upwards trend.The k-N relationship curve displays an increasing trend with the concentration and a general downwards trend as the dynamic stress amplitude is made higher.This also indicates that sodium chloride solutions can improve the engineering properties of expansive soil to a certain extent.With an increase in the vibration times N,the shape of the hysteretic curve becomes narrower,and the whole soil exhibits a cyclic strain hardening.With the help of an exponential function,a model is introduced to predict the relationship between the concentration and the hysteretic curve.
基金sponsored by National Natural Science Foundation of China(No.52308466,No.42271144,No.42071100)Key Research and Development Project of Shaanxi Province(2022SF-328,2022GY-427)+1 种基金the SASAC Science and Technology Innovation Project(JF-23-01-0063)Shaanxi Provincial Transportation Research Project(24-19K,24-20K).
文摘Waste plastics and rubber have always posed a threat to the environment and a great challenge for disposal.The use of these two waste materials as modifiers for road asphalt provides new road asphalt binders and at the same time provides a new way for waste material resource treatment.Rubber-modified asphalt and plastic-modified asphalt have received widespread attention due to their green and low-carbon characteristics and some performance advantages,but there are still some performance shortcomings that hinder their promotion and application.In order to continue to explore the application of waste materials in the field of road engineering,combined with the performance advantages of both,many scholars began to study the rubber-plastic composite modified asphalt(RPCMA).Therefore,this paper reviewed the different types of waste rubber and plastic,the comprehensive performance of different types of asphalt and its mixture performance,analyzed the modification mechanism of rubber-plastic composite modified asphalt and its performance changes.The results show that rubber-plastic composite modified asphalt is mostly prepared by directly adding modified materials.However,the pretreatment or melt granulation of rubber and plastic will make the performance of rubber-plastic modified asphalt has improved.There is a mutual promotion mechanism between rubber and plastic in asphalt,which makes the performance of rubber-plastic modified asphalt better than that of asphalt obtained by a single modification method(rubber modified asphalt or plastic modified asphalt).In some properties,it can be close to the commercial SBS modified asphalt.The performance of rubber and plastic composite modified asphalt at high temperature has been generally recognized by researchers,but its low-temperature performance is still controversial.Therefore,it is recommended to apply in high-temperature areas.Future work should focus on the development of composite modifiers with stable performance,low cost and ease of use,standardization of modification processes,improvement of low-temperature performance,and monitoring of road performance and environmental impact.
