Interfacial Behavior Of Asphalt Mastics And Its Mechanism

Nowadays, early-damage of asphalt pavement is very serious in China, and thedamage types are complex, which affect driving safety and comfort seriously,reduce the quality of road usage, shorten the service life of the pavement. Sosolving the early damage of the asphalt pavement is very necessary to current roadconstruction and management in China. The existing research shows that thematerials and structures are the two most important factors effecting asphaltpavement performance. The materials used in the asphalt pavement are asphaltmixtures, and the asphalt mastics is the most important composition in its threelevels of distributed systems, which determines the performance and life of asphaltmixtures. Asphalt mastics consists of asphalt, fillers and interface, and the interfacephase is often ignored because it is difficult to catch. But the actual experience hasshown that the damage of asphalt mastics often happen on the interface phasebecause it is fickle.In this dissertation, dynamic mechanical analysis (DMA), differential scanningcalorimetry (DSC), surface physical chemistry method, and a variety of micro-characterization techniques are used to studied phase structure, interaction, bondingadhesion and other physical and chemical phenomena of asphalt mastics, andrevealed the mechanism of the interfacial behavior. The main research includes thefollowing:Firstly, a variety of phase transitions of asphalt mastics can occur because theworking temperature is very wide in China, even vary between-40°C and70°C innorthern China. So the structures and properties of interface have always beenchanging. This dissertation used DMA and DSC to study phase structure and phasebehavior of asphalt mastics, and analyzed the variation of the phase interface.Secondly, the microscopic mechanism of the asphalt mastics still stays in theinteraction theory of Л.A. Liebinjieer, and nobody has confirmed the correctness ofthe theory by experiment. This dissertation estimated the interfacial layer thicknessof asphalt mastics by DSC, analyzed the interaction of asphalt and fillers and itsevaluation index by DMA, and studied the complex interface behavior of the three-phase system by the Carreau viscosity model.Thirdly, water damage of the asphalt pavement has become a common anddifficult damage form, and researchers have confirmed that such damage is causedby the adhesion or cohesion failure of the asphalt and aggregate, but the internal cohesion and adhesion characteristics of asphalt mastics have never beeninvestigated. In this dissertation, the surface physical and chemical means are usedto test surface free energy and its components of asphalt and filler, calculate thecohesive and adhesive works between asphalt and fillers, analyze the influencefactors of cohesive and adhesive, and the consistency of the surface energy theoryand DMA was obtained.Finally, a variety of micro-testing techniques were used to analyze themechanism of the interface behavior. Atomic force microscopy (AFM) was used totest nano-morphology and nano-adhesive force of asphalt and fillers, and the factorsinfluencing them were analyzed. Fourier transform infrared spectroscopy (FTIR)was used to analyze the chemical bond of bitumen and filler. The adsorption testwas applied to study the adsorption and desorption characteristics of asphalt andmineral aggregate. The adsorption isotherm was used to distinguish the physicaland chemical actions between asphalt and mineral aggregate.