Characterization of Load Transfer Behavior for Bonded Concrete Overlays on Asphalt

Abstract

A bonded concrete overlay on asphalt (BCOA) is a rehabilitation method for moderately distressed asphalt pavements by relatively thin plain cement concrete or fiber-reinforced concrete slabs. The joint load transfer behavior for BCOAs plays a significant role in the long-term performance. Poor load transfer across the joints of the concrete slabs initiates debonding of the asphalt layer from the concrete slabs, which promotes the development of corner cracks or longitudinal cracks. However, because of the tediousness involved in characterizing the joint load transfer behavior of BCOAs, this important aspect is not accounted for in many available mechanistic–empirical BCOA design procedures. The influences of joint load transfer behavior on the performance of BCOA are discussed. The joint load transfer behavior for BCOAs with 1.52- × 1.83-m (5- × 6-ft) slabs and 1.22- × 1.22-m (4- × 4-ft) slabs is analyzed with the finite element method. The load transfer contributed by the asphalt layer, as well as the concrete slab, is characterized as a function of the BCOA design features. Finally, a method is proposed to determine the nondimensional joint stiffness (AGG*) for BCOAs as a function of the structural design features of the pavement section. The AGG* is significant in that it is the factor commonly used to characterize joint load transfer behavior when pavements are designed with a mechanistic-based design approach.

Mechanical Connectors to Enhance the Interfacial Debonding of Concrete Overlays

“…Owing to slab discontinuities, top and bottom layers are unable to deform jointly, and consequently σtr,v emerges in the interface. These stresses increase when load transmission between adjacent slabs is poor and are also the leading cause of premature failure in whitetoppings [10,12]. Horizontal traffic loads (braking, acceleration, and centrifugal forces of vehicles) are applied by the wheel on the surface of the pavement.…”

“…Joint properties determine load transfer between adjacent slabs and water penetration towards the interface. Load transfer between two adjacent slabs [32] is produced by both the effect of aggregate interlocking and continuity of the bottom layer of the pavement [10,33]. Fibers also contribute to improving the load transmission by limiting joint and cracks opening and generating a dowel bar effect [34].…”

“…Fibers also contribute to improving the load transmission by limiting joint and cracks opening and generating a dowel bar effect [34]. Proper load transfer reduces the magnitude of normal debonding stress on the unloaded slab [10].…”

“…In recent decades, many studies were carried out to understand the mechanisms of bonding and debonding [5][6][7][8][9][10][11][12][13] and to bring recommendations for the maximization of the interfacial strength between layers in the whitetopping and overlays [8,[14][15][16]. Moreover, some technical reports that give guidelines to select interfacial treatments and good construction practices were also published [4,15,17].…”