Determining Normal and Shear Pull-off Strength of Asphalt Mastic Films due to Diffusion of Water Vapor

In this study, normal and shear pull-off strength of asphalt mastic films are measured at three Relative Humidity (RH) conditions. Mastic films of size 5 mm² with thickness ranges from 0.193 mm to 0.210 mm were prepared in between two aggregate slices. Laboratory RH conditioning was applied by aqueous solution of Potassium Acetate (25% RH), Potassium Carbonate (49% RH), and Sodium Chloride (71% RH) in enclosed desiccators. After humidity conditioning, one aggregate slice was attached to the base of a testing frame, and pull-off force was applied on the other aggregate slice. Load-displacement curves indicate that mastic films show ductile behavior at high RH% conditioning and brittle behavior at low RH% conditioning while normal pull-off strength is measured. Mastic films behave more ductile by showing a definite yield point, ultimate strength, and failure strength with high elongation at 71% RH. However, at 49% RH, mastic films tear down abruptly like elastic-perfectly plastic material. At 25% RH, mastic films tear down suddenly like a brittle material. Average yield and ultimate strength for 71% RH is the lowest compared to those at 49% and 25% RH. The ductile nature of mastic films at high RH% influences the shear pull-off strength by showing higher shear pull-off strength. Average shear strength of mastic films increases with an increase in relative humidity. As humidity increases, viscosity decreases and elasticity increases due to diffusion and absorption of vapors in the mastic. Reduction in viscosity causes insufficient bonding between aggregates and mastic materials, and accelerates damage.

  • Supplemental Notes:
    • This paper was sponsored by TRB committee AFK20 Characteristics of Asphalt Materials.
  • Corporate Authors:

    Transportation Research Board

    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Authors:
    • Hossain, Mohammad I
    • Tarefder, Rafiqul A
  • Conference:
  • Date: 2014

Language

  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; References;
  • Pagination: 17p
  • Monograph Title: TRB 93rd Annual Meeting Compendium of Papers

Subject/Index Terms

Filing Info

  • Accession Number: 01506463
  • Record Type: Publication
  • Report/Paper Numbers: 14-1285
  • Files: TRIS, TRB, ATRI
  • Created Date: Feb 3 2014 12:23PM