Shear Strength and Influence of Thin Asphalt Overlays on Cement Pavement. (English)

In view of shear failure of thin asphalt overlays on old cement concrete pavement, three types of tack coat oil (ordinary emulsified asphalt, SBS modified emulsified asphalt and self-made high-performance emulsified asphalt), three types of overlay mixtures (AC-10, SMA-10 and DTFC-10) and three kinds of underlying surface roughness (initial texturing, chiseling, and grooving) were selected to prepared compound pavement. The effects of various factors, such as the type and dosage of the tack coat oil, the type of the overlay mixtures and the surface roughness of the existing cement pavement, on the interlayer shear strength were evaluated by the direct shear test. In addition, the influence degrees of various factors were analyzed though gray theory. The results showed that the type of tack coat oil had a significant effect on the interlayer shear strength. Furthermore, the interlayer shear strength first increased and then decreased with the increase of the tack coat oil consumption. And the shear strength reached the maximum value when the amount of the tack coat oil was 0.8 L/m². The effects of the overlay asphalt mixtures type on the interlayer shear strength were significant, and the values of ultra-thin wear course DTFC-10 were greater than other two mixtures. The surface textural behavior of concrete pavement also had positive contribution to the interlayer shear strength. The shear strength values of underlying surface treated by chiseling method were slightly higher than that treated by grooving method. While, the values of those two textured surface were obviously greater than the initial surface. Cray correlation analysis revealed that the interlayer shear strength were notable dependent on the thin HMA overlays and the tack coat oil. Moreover, the surface texture of cement concrete pavement and the consumption of tack coat oil also had a certain influence. [ABSTRACT FROM AUTHOR]

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