This paper investigates the effect of processes on fatigue fracture and healing during controlled-strain, dynamic mechanical analysis (DMA) testing. Sand asphalt samples were fabricated with two SHRP-classified binders: AAD-1 AAM-1. DMA testing was performed at 25°C 10 Hz. The response monitored using three different damage indicators: (1) change in modulus; (2) pseudo stiffness; (3) dissipated strain energy. When either these parameters are plotted versus number load cycles, inflection...

Expansive clay soils—those that change significantly in volume with changes water content—are the cause of distortions to structures cost taxpayers several billion dollars annually United States. Much has been learned about their behavior over past 60 years, and relatively successful methods have developed modify stabilize them. This paper reviews some key advances years improving our understanding nature modifying stabilizing expansive soils. The state practice stabilization is presented,...

The ability to quantify adhesion based on surface energies of the bitumen and aggregate components enables selection compatible materials quantitative assessment moisture susceptibility. Reliable energy characterization is required in order implement this technology successfully. One proven method estimate calculate it using contact angles measured with various liquids. However, improper probe liquids or interpretation resulting data can easily mislead users into drawing inaccurate...

Conventional methods to quantify the moisture sensitivity of asphalt mixtures are based on comparison mechanical properties mix before and after a moisture-conditioning process. Although this approach consolidates effect material mixture sensitivity, it does not identify causes responsible for poor or good performance mixture. In study, surface free energy binders aggregates was used derive parameters that various combinations materials. The 12 carefully designed represent wide range...

Moisture damage in asphalt concrete pavements is a major cause for high maintenance costs of state and federal highways. largely due to loss adhesion between bitumen aggregate, cohesive strength the mastic (bitumen mineral filler). Surface energy components aggregate are used calculate their interfacial bond effectively quantify moisture susceptibility mixes. This technology has several advantages over conventional mechanical tests currently being identify susceptible However, accurate...

Hydrated lime is evaluated as a filler in bitumen and compared to similarly sized comprised of calcium carbonate, limestone. Extensive laboratory testing considered, including rheological mastics (with dynamic shear rheometer, mechanical analyzer, bending beam rheometer); low temperature elongation fracture tests on mastics; torsional fatigue mixtures; permanent deformation mixtures. These confirm that hydrated significantly impacts the rate level microcrack-induced damage, microdamage...

The fatigue-cracking life of an asphalt mixture measured in the laboratory is generally a small fraction observed field. One reasons for this large difference self-healing property binders. Self-healing process that reverses growth fatigue cracks during rest periods between load applications. A thorough understanding healing mechanism required to accurately model and predict influence on mixtures. Previous studies have used experimental evidence demonstrate correlation chemistry functional...

The dynamic shear rheometer (DSR) is used to characterize linear viscoelastic properties of asphalt cement and mastic (asphalt with a filler that smaller than 75 μm in size). study focuses on using micromechanical rheology-based models assess the effect two fillers, limestone hydrated lime, performance mastic. Two distinctly, compositionally different cements were selected effect. Micromechanical reviewed, most appropriate these behavior (composite). Since are developed for elastic...

This paper presents a mechanistic approach to constitutive modeling of asphalt concrete under complicated repetitive loading conditions with rest periods. From an extensive literature review, two mechanisms are identified as important understanding inelastic stress‐strain behavior concrete: vis‐coelastic relaxation and fatigue damage accumulation process. The nonlinear viscoelastic correspondence principle developed by Schapery is applied separate the influences these hysteresis concrete....

The loss of physical adhesion between the aggregate and asphalt binder is one important mechanisms that accelerate moisture damage in hot-mix pavements. In this study, two parameters related to bond energy—adhesive energy reduction free when debonds from surface presence moisture—were quantified with energies both materials. Threshold values these identify asphalt-aggregate combinations susceptible premature were derived by comparison observed field performance for several mixes. Results...

ABSTRACT Significant evidence exists in the literature that healing has a substantial effect on performance of asphalt mixtures and therefore pavements. The incorporation mechanism tandem with crack growth is necessary for comprehensive modeling fatigue or fracture processes mixtures. This paper presents new framework combines material mechanical properties bitumen to predict mixture. based an analytical approach will allow it be incorporated future models damage. also test method using...

This paper semiquantitatively evaluates the microrheological properties of asphalt binder using atomic force microscopy. It also presents differences between these amongst various microstructures within an binder, in addition to influence oxidative aging on properties. Nano-indentation experiments performed a microgrid phases determined micromechanical such as stiffness, adhesion, and elastic/plastic behavior. The evaluated materials include asphalts AAB, AAD, ABD from Materials Reference...

AbstractThe primary objective of this paper was to investigate the impact asphalt chemical composition on microstructure and performance characteristics binder. The methods implemented in study include adsorption–desorption chromatography analysis a range atomic force microscopy (AFM) techniques. It revealed through that certain parameters have consistent measureable effect is observed with AFM. Particular microstructures emerged via doping were then discovered unique polarity, which...

The pseudo-strain concept based on Schapery’s extended nonlinear elastic-viscoelastic correspondence principle is demonstrated by a considerable database to be able characterize both microdamage and healing during the damage process. A change in pseudo stiffness can used quantify fatigue test. Pseudo decreases consistently with increasing number of loading cycles, indicating that occurs significant recovery after rest periods demonstrates effect due periods. Dissipated energy strong...

Cohesive and adhesive bonding within the asphalt—aggregate system are directly related to surface energy of asphalt. The thermodynamic changes in adhesion cohesion de-bonding interface between asphalt aggregate cracks that may occur mastic, respectively. However, it is also true required heal a fracture surfaces or mastic. methodology testing protocol for measuring presented. Both dewetting (fracture) wetting (healing) can be obtained from contact angle measurement with Wilhelmy plate...

This research is intended to contribute toward the understanding, development, and implementation of a more fundamental design process for bituminous pavement materials, utilizing thermodynamic properties materials involved. The theory developed by van Oss, Chaudhury Good forms basis this research. Optimization techniques characterize surface energy, as well consideration evaluation additional factors that influence adhesion in presence water, are pursued. A synthesis theories mechanisms...

Complex characteristics of fatigue behavior were evaluated on the basis test results and their mechanical analyses. The dynamic shear rheometer was used to characterize fundamental linear viscoelastic properties asphalt binders mastics. Various tests using cylindrical sand–asphalt samples mixed with pure binders, mastics, or both also performed estimate behavior. To assess filler effect, two distinctly compositionally different AAD-1 AAM-1, fillers, limestone hydrated lime, selected. Test...

Two moisture damage models based on major failure mechanisms are proposed. The adhesion model was developed to analyze the adhesive fracture between asphalt and aggregate in presence of water. Cohesive fractures an asphalt-aggregate system directly related surface energy characteristics aggregate. with or without water can be calculated from energies A diffusion one-dimensional consolidation soil a gas adsorption model. used obtain binders, including amount that permeate binder diffusivity...