Influence of Interface Characteristics on the Shear Performance between Open-Graded Friction Course and Underlying Layer

This laboratory study evaluated the influence of interface characteristics on the bonding properties between open-graded friction courses (OGFC) and the underlying layer. One gravel OGFC and two commonly used underlying layers [one base material (BM) and one thin-layer D mixture (TLD)] were used in this study. The BM is a regular asphalt binder course mixture with 19-mm nominal maximum aggregate size, whereas the TLD is a thin asphalt surface-wearing course mixture with 12.5-mm nominal maximum aggregate size. A direct shear test was performed to obtain the shear strength and shear stiffness at different tack-coat application rates. Adhesive and cohesive failure types on the interfaces were identified. Noncontact area between OGFC and underlying was obtained. Results showed that there were no significant differences in adhesive failure area between OGFC-TLD and OGFC-BM. The cohesive failure area of OGFC-TLD was larger than that of OGFC-BM. The noncontact area between OGFC and BM was larger in contrast with the area between OGFC and TLD at the same tack-coat application rate. With an increase in tack-coat application rate, the adhesive failure area and noncontact area decreased and cohesive failure area increased. The shear force to overcome the adhesive bonding between OGFC and BM was larger than that of OGFC and TLD at the same tack-coat application rate because of the larger interface roughness caused by BM’s coarser aggregate gradation. At the optimal tack-coat application rates for OGFC-TLD and OGFC-BM, the difference in shear force to overcome the cohesive bonding between OGFC-BM and OGFC-TLD was very slight. The shear force to overcome the adhesive bonding is the factor that made the shear strength and shear stiffness of OGFC-BM larger than those of OGFC-TLD.

Language

  • English

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Filing Info

  • Accession Number: 01633224
  • Record Type: Publication
  • Files: TRIS, ASCE
  • Created Date: Apr 7 2017 3:02PM