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Micromechanical Modeling the Viscoelastic Performance of the Asphalt Concrete with Finite Element

Mohammad Karimi, Mohammad | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43804 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Tabatabaee, Nader
  7. Abstract:
  8. Asphalt concrete is a composite mixture of three phases; aggregate, bitumen and air void. Stress and strain distributions obtained from macroscopic modeling yield different results due to distinctly different mechanical properties of the above-mentioned phases. In this study a more exact analysis of the stress and strain, were carried out by considering the mixture as a two-phase composite; aggregate and mastic phases. Asphalt concrete was considered a composite material consisted of sand mastic and aggregate. Aggregate and mastic phases were separated and response of the loaded asphalt mixture was investigated. Aggregates finer than 2.36 mm in diameter, filler and bitumen consist the mastic phase, whereas aggregates larger than 2.36mm consist the aggregate phase. The images of the asphalt concrete cross sections obtained by high-resolution-scanner and digital image processing techniques were used to identify the boundaries of each phase. Mastic phase was assumed as a homogeneous and isotropic material with viscoelastic properties, whereas, the aggregate phase as a linear elastic material. Digital image correlation (DIC) technique was adapted to measure full field strain and displacement of loaded specimen. Micromechanical response of asphalt concrete samples under IDT loading were determined by applying DIC technique on the images of deformed cross section of asphalt concrete. Strain and displacement distributions in horizontal and vertical directions were compared with those obtained from micromechanical modeling of IDT test through Finite Element (FE) analysis. Also actual stress distribution in asphalt concrete was investigated for different value of aggregate and sand mastic elasticity modulus’s ratio. Also some of the viscoelastic property of the asphalt concrete such as creep compliance, relaxation modulus, complex modulus and phase angle are investigated for different direction of sample loading. Response of the asphalt mixture is studied for loaded sample in different displacement rate, too. Laboratory tests and simulation results show that FE micromechanical modeling of asphalt concrete is an appropriate means of obtaining the actual strain and stress distribution in different points of asphalt concrete cross section. Also DIC is a good technique for measuring strain and displacement distribution in loaded sample in laboratory
  9. Keywords:
  10. Image Processing ; Finite Element Method ; Micromechanical Modeling ; Asphalt Concrete ; Digital Image Correlation

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