Interface bonding between hot-mix asphalt (HMA) overlays and Portland cement concrete (PCC) pavements is one of the most significant factors affecting overlay service life. In this study, accelerated pavement testing (APT) was performed to quantify the effects of tack coat type, tack coat application rate, and PCC surface texture on the interface bonding and overlay performance. This study builds on and validates previously completed laboratory tests where an HMA overlay was placed on top of an existing PCC pavement having various surface textures, including smooth, transverse tining,and milling. Asphalt emulsion SS-1hP and cutback asphalt RC-70 were applied at three residual application rates: 0.02, 0.04, and 0.09 gal/yd2. Asphalt binder PG64-22 was applied at 0.04 gal/yd2. As part of this study, 25pavement test sections were constructed and loaded with the Accelerated Transportation Loading ASsembly (ATLAS) at the centerline. The tensile strains at the bottom of HMA, to quantify potential interface slippage, were measured for selective sections, and primary HMA rutting was analyzed for all sections. The study validated the laboratory-determined optimum tack coat application rate, which provides the lowest interface strain and surface rutting in the field. Both PG64-22 and SS-1hP showed better rutting resistance than RC-70. Milled PCC surface provided lower rutting than transverse tined and smooth surfaces. The study also shows that PCC cleaning methods play an important role in the HMA-PCC bonding.
Samenvatting