Full-Scale Evaluation of Concrete-Asphalt Interphase in Thin Bonded Concrete Overlay on Asphalt Pavements

Abstract

Thin bonded concrete overlay on asphalt (BCOA) pavements rely on concrete-asphalt bonding to resist traffic loading. To investigate variables affecting bonding, experimental data were used from 15 instrumented thin BCOA sections, with 11 tested with heavy vehicle simulators (HVS). Sections included three slab sizes, four rapid-strength concrete mixes, new and old asphalt bases, and three asphalt surface texturing techniques. Analysis of strain data from HVS testing served to determine the concrete-asphalt bonding condition. Laboratory testing and forensic data from the sections were also evaluated. Overall, the performance of concrete-asphalt bonding in the sections with 1.8 × 1.8 m (6 × 6 ft) slabs was excellent. In these sections, concrete-asphalt bonding remained intact throughout the HVS testing despite the unfavorable testing conditions, which included flooding of the section, channelized traffic at the slab edge, and HVS wheel (half axle) loading of up to 100 kN (22.5 kips). The sections with 3.6 × 3.6 m (12 × 12 ft) slabs presented a delamination band between the asphalt and concrete along the perimeter of the slabs. This delamination was a tensile break occurring in the asphalt around 5–10 mm (0.2–0.4 in.) below the concrete-asphalt interphase caused by the large vertical hygrothermal deformations in the slabs. Because of this asphalt failure, the concrete and asphalt worked as two independent layers near the transverse joints. Based on laboratory procedures, it was observed that cement paste penetration into the asphalt layer caused a reinforcing effect in the concrete-asphalt interphase. It was also observed that milling and micromilling did not improve the concrete-asphalt bonding.

Accelerated Testing of Full-Scale Thin Bonded Concrete Overlay of Asphalt

“…The poor performance of Section J, compared with Section I, was attributed to debonding between the concrete slabs and the asphalt base that occurred at the transverse joints and to a lesser extent at the longitudinal edges of the slabs. This hypothesis agreed with the fact that traffic-loading–induced strain measured in Section J at the top of the asphalt layer near the transverse joints was compressive ( 12 ). The same occurred in Section K, whose slabs were also 12 × 12.…”

“…The excellent performance of the sections with new RHMA-G contradicts—apparently—Colorado’s thin BCOA recommendations ( 11 ), which state that “concrete does not bond well to a new AC pavement, milled or not.” The good performance of the bonding between concrete and new RHMA-G was also verified in the laboratory ( 12 ).…”

“…Most of the cores extracted from this milled HMA section presented either asphalt surface damage or concrete-asphalt debonding. On the other hand, most of the cores extracted from the sections with micromilled old HMA showed the asphalt and the concrete-asphalt interface to be in good condition ( 12 ).…”

Full-Scale Experimental Evaluation of the Flood Resiliency of Thin Concrete Overlay on Asphalt Pavements

“…The five sections studied in this research are part of a wider experiment that focused on the implementation of COA in California, U.S. The experiment was conducted for the California Department of Transportation (Caltrans) between 2014 and 2017 ( 12 , 13 ). As part of this wider experiment, 11 COA sections were tested with the HVS.…”

Design of Cold-Mixed High-Toughness Ultra-Thin Asphalt Layer towards Sustainable Pavement Construction

“…This is because the thickness of the wear layer is reduced. It leads to the growth of the tensile stress of the bottom layer, the fatigue damage rate of the structural layer, and the shear force between the layers [16][17][18]. In order to enhance the durability and stability of the ultra-thin wear layer, scholars focused on the improvement of asphalt materials and the optimization of the grading design.…”