Evaluation And Influencing Factors Of Interfacial Bonding Properties Between Asphalt And Aggregate

Water damage is one of the major diseases of asphalt pavement.Once it occurs,it will accelerate the generation of other diseases and greatly reduce the road performance of pavement.The interfacial adhesion between asphalt and aggregate directly affects the water stability of asphalt pavement.Therefore,it is of great significance to carry out the research on the interfacial adhesion between asphalt and aggregate.Traditional boiled and water immersion methods are easily influenced by subjective and can only be used as qualitatively.In this thesis,the Photoshop pixel analysis method and SHRP net adsorption method were used to quantitatively study the interfacial adhesion between asphalt and aggregates as well as its influencing factors.In the end,the freeze-thaw splitting test was used to evaluate water stability of asphalt mixture.First,the X-ray diffraction were used to analyze the chemical elements and composition of three different types of aggregates which were then classified according to their SiO₂ content.Limestone was defined as alkaline aggregate,basalt as neutral aggregate,and granite as acidic aggregate.On the other hand,the main four components of asphalt were determined as asphaltenes,gums,saturated components and aromatics.The 135°C viscosity of the asphalt was measured and the effect of aging on the four components and viscosity was analyzed.Second,the temperature and aging effect on adhesion were studied by the combination of water immersion method and Photoshop pixel analysis,the following conclusion is obtained:Photoshop pixel analysis method is used to quantitatively analyze the adhesive properties of asphalt and aggregate.For the same grade of asphalt,the higher alkalinity content one has,the better adhesiveness it could be.On the other hand,for the same type of aggregate,The greater the ratio of gum to asphaltene,the better adhesion.The peeling off temperature is not the same when it comes to different combination of asphalts and aggregates.Good adhesion system has high peeling off temperature whereas peeling occurs at relative low temperature for bad combinations;The adhesion between the aged asphalt and different aggregates has a random pattern,not just the rising viscosity of aged asphalt leading to a better adhesiveness consequence,indicating that viscosity is not the only factor that affects adhesion.Third,we used SHRP net adsorption method to evaluate the adhesion rate of asphalt,the following conclusions are drawn:with the increase of adsorption time,the adsorption capacity between asphalt and aggregate increases as a whole,and finally tends to a stable state.With the increase of the desorption time,the net adsorption amount of asphalt and aggregate appeared two changes:1,the net adsorption capacity gradually decreased and finally tended to stabilize;2,the net adsorption amount increased first and then decreased to the stability.We used SHRP net adsorption method to evaluate the adhesion rate of asphalt and aggregates with 4 hours adsorption time and 2 hours desorption time.SHRP net adsorption method could lead to the same conclusion as water immersion did,meaning that using SHRP net adsorption method to measure the adhesion of asphalt and aggregates is feasible.This method is highly accurate and could quantitatively evaluate the adhesiveness performance.Finally,a table of adhesion between asphalt and different aggregates is established.Fourth,a large number of limestones and basalts were subjected to freeze-thaw splitting tests and the freeze-thaw splitting strength ratios were counted.The grey correlation theory was used to analyze the factors affecting the asphalt pavement water stability.Through the analysis,asphalt saturation is the most important indicator of asphalt water stability.Therefore,asphalt saturation should be controlled within a reasonable range to ensure that the asphalt pavement has good road performance.