Influence of Constant Micro Strain Levels on the Strength Properties of the Asphalt Concrete mixture

Abstract

Asphalt concrete mixture is designed to resist the deformation and vehicular traffic loading throughout its service life. However, when the asphalt concrete pavement practices over loading within the service life period, it exhibits cracking and rutting. In the present investigation, an attempt has been taken to understand the strength performance of asphalt concrete when practicing variable levels of constant stresses. Asphalt concrete mixture was prepared at optimum asphalt cement requirement and compacted in a slab mold of (60 x 300 x 400) mm and subjected to roller compaction to the target bulk density. Beam specimens of 63 mm width, 50 mm depth, and 400 mm length were obtained from the compacted slab sample using the Diamond-saw. The beam specimens were tested for fatigue life under constant strain levels of 250, 400, and 750 with the aid of the four-points repeated flexural bending beam test to verify the influence of constant strain levels on the permanent deformation, fatigue life, flexural stiffness, and its resistance to flexural stresses. Test was conducted under 20 °C environment. It was concluded that the permanent deformation increases by (11, and 29) folds as the constant strain level raised from 250 to 400 and 750 respectively. The fatigue life declines by (95 and 99.1) percentage when the constant strain level increases from 250 to 400 and 750 respectively. The flexural stiffness declines by (16.6 and 20.8) percentage when the constant strain level increases from 250 to 400 and 750 respectively.