Study On Performance Of Modified Asphalt And Mixture By Shape Stabilized Composite Phase Change Materials

Asphalt pavements are prone to high temperatures due to solar radiation in summer.Under the effect of traffic loading,rutting,pushing,other high-temperature diseases occur,which seriously affects the service life and service quality of pavements.In recent years,with the development of multi-disciplinary integration,providing a new idea for solve pavement high-temperature disease to the active reduction of pavement temperature,which has been widely concerned by domestic and foreign scholars.Based on the theory of phase change temperature control in this paper,a new shape stabilized composite phase change material for asphalt pavements had prepared.Firstly,two kinds of different phase change materials were selected as the foundation temperature-adjusting materials,and expanded graphite was chosen as the carrier heat conduction network.The composite phase change materials were prepared by the vacuum impregnation method.Whereafter encapsulated and shaped by epoxy resin,form-shaped compound phase change materials suitable for the temperature-adjusting of asphalt pavement were obtained.The results show that the composited phase change materials had a physical combination,excellent chemical stability,and thermal stability,and they mainly meet the needs of temperature-adjusting pavement.The encapsulation system can effectively reduce the leakage of phase change materials.The phase transition temperature and enthalpy were 48.93℃ and 106.5 J/g,respectively,and meet the requirements of high-temperature production and long-term recycling of asphalt mixture.Secondly,the influence of fixed composite phase change material on asphalt performance was studied,including rheology,aging resistance,and temperature-adjusting effect.There are no significant free phase change materials in the phase change modified asphalt binders,which proved that the encapsulation effect was well.The addition of form-shaped composite phase change material improves the high-temperature stability,viscosity,and the crack resistance of the low-temperature reduced to a certain extent of the matrix asphalt.The internal for phase change modified asphalt binders with 20%content can be reduced maximum temperature by 10.4℃.After aging,the survival rate of form-shaped composite phase change material in asphalt binders can reach 88.0%,and it still had excellent heat storage and temperature-adjusting ability.The volatilization of the free phase change material was the main reason for the aging resistance of the phase change modified asphalt binders reduced.Finally,form-shaped composite phase change material was applied to asphalt mixtures,and study the influence of mixing content on the temperature-adjusting performance and pavement performance of asphalt mixtures.Adding form-shaped composite phase change material into asphalt mixtures by equal volume substitution method can effectively delay the heating rate of asphalt pavement and reduce its peak temperature.And the temperature-adjusting effect of the temperature-adjusting asphalt mixtures was remarkable.With the increase of mixing content,the temperature-adjusting effect of temperature-adjusting asphalt mixtures would increase,but the pavement performance would decrease.When the replacement content of shape stabilized composite phase change materials was 2.0%,the pavement performance indexes of temperature-adjusting asphalt mixtures can meet the specification requirements.And the asphalt pavement at a depth of 5cm can be reduced temperature of 3.7℃.Temperature-adjusting asphalt mixtures use the phase-change heat storage characteristics of the phase-change materials to realize the temperature-adjusting of asphalt pavement.Application of phase change materials can effectively reduce the peak temperature of pavements,broaden the application range of pavement temperature-adjusting materials,and providing a reference for the development of temperature-adjusting pavements.