Study On Water Stability And Failure Mechanism Of Hot Recycled Asphalt Mixture

With the development of transportation,recycling technology of waste asphalt mixture has been widely applied to the process of China's highway construction,hot recycled asphalt mixture with its wide applicability,accurate measurement,the construction quality can be guaranteed by a series of advantages such as a large number of applications,engineering experience shows that heat regenerative high temperature performance of asphalt mixture better than ordinary asphalt mixture,but its water stability was reduced.In this paper,based on the theory of aggregate asphalt adhesion,the strength and water stability of hot recycled asphalt mixture are studied systematically.In this paper,on the premise of ensuring the performance of raw materials,the Marshall design method is used to design the recycled asphalt mixture.On this basis,the influence of the factors such as the amount of old material,aggregate type,recycling agent and void fraction on the splitting strength and water stability of recycled asphalt mixture was studied by freeze-thaw splitting test.The results showed that with the increase of old material content,recycled asphalt mixture splitting strength increases while TSR decreases;the old material volume under the same conditions,the limestone mixture splitting strength and TSR were higher than that of granite;with the addition of regeneration agent,mixture splitting strength slightly decreases TSR increased slightly;with the increase of void ratio,mixture splitting strength and TSR were decreased.The sessile drop method for the determination of the corresponding with the old material content of the surface aging of asphalt and component changes and determination of regenerated asphalt surface free energy and its components;surface free energy components of limestone and granite and tested by wick column method.Based on the surface energy theory,the adhesion of asphalt and the adhesion work of asphalt were calculated.The results show that with the increase of the aging level of asphalt,asphalt cohesive power and adhesion work between the asphalt material increased,adhesion work of asphalt and the same limestone than granite;work of adhesion agent is added after the recycled aggregate asphalt decreased.The tensile test of temperature,and the influence of the aging level of asphalt aggregate types,regeneration agent,water and other factors on the interfacial bonding properties of asphalt material in use;in addition,the low temperature nitrogenadsorption test and SEM test analysis of aggregate surface morphology.The results show that the pull-out specimens at low temperature(0 ?)under adhesion failure at room temperature(20 ?)under the cohesion failure;the higher the aging level of asphalt,the interfacial bond strength is higher;the interfacial bond strength of asphalt and limestone same than granite;added to the aging asphalt recycling agent will make the interfacial bond strength decreased;under the action of water,aggregate asphalt interfacial bond strength decreased significantly;the aggregate surface area measurements show that the limestone surface area than granite,the results of SEM observation showed that the surface morphology of limestone than granite rough.The aggregate adhesion properties of recycled asphalt and asphalt mixture water stability correlation analysis can be drawn: the change rule and the asphalt mixture surface free energy and work of adhesion of splitting tensile strength of variation,indicating the surface free energy of asphalt,the adhesion work of asphalt and aggregate is large,the corresponding mixture splitting strength it has water,ratio of material;analysis ? of asphalt adhesion work and the difference between the anhydrous state adhesion work set under the condition of water,? and TSR showed more consistent trend,mixture water stability is better;to analyze the relationship between aggregate asphalt mixture and the corresponding interfacial bond strength splitting strength,both positive related changes the size of the interfacial bond strength can be explained by splitting tensile strength of variation;comparison of tensile specimens of freeze-thaw strength ratio of mixture and the relationship between TSR and the trend of the two,from the Analysis of water stability of asphalt mixture interface is reasonable.