Volume 20, Issue 53, January - June, 2023

Variation of initial stiffness under variable strain levels and binder content

Saad Issa Sarsam^♦

Director, Sarsam and Associates Consult Bureau (SACB), Baghdad, Iraq/Professor and former Head, Department of Civil Engineering, College of Engineering, University of Baghdad, Iraq

^♦Corresponding author
Director, Sarsam and Associates Consult Bureau (SACB), Baghdad, Iraq/Professor and former Head; Department of Civil Engineering, College of Engineering, University of Baghdad, Iraq

ABSTRACT

At moderate pavement temperature, the initial stiffness of asphalt concrete is controlled by the asphalt binder content and can sustain the various vehicular loading. The aim of the present investigation is to monitor the variation in the initial flexural stiffness percentage throughout the asphalt concrete fatigue life among variable constant strain levels and asphalt binder content. Mixtures of Asphalt concrete were prepared in the laboratory using the optimum binder content and extra mixtures were prepared with a variation in the binder content of ± 0.5% within the optimum asphalt contents as a service tolerance during the asphalt mixture preparation process. The mixtures were compacted in a slab mold using laboratory rollers. Beam specimens of asphalt concrete have been obtained from the prepared slab samples and tested under dynamic flexural stresses under three constant microstrain levels of (750, 400 and 250) and tested for flexure at 20℃ environments. It was noticed that the asphalt concrete fatigue life at 400 microstrain level decline by (95, 86.6 and 96.5) % for mixtures prepared with (4.8, 4.3 and 5.3) % asphalt cement binder respectively as compared with mixtures sustaining constant microstrain level of 250. However, the fatigue life at 750 microstrain level decline by (98.1, 83.3 and 96.5) % for mixtures prepared with (4.8, 4.3 and 5.3) % asphalt cement binder respectively as compared with mixtures sustaining constant microstrain level of 250.

Keywords: Constant strain level, asphalt concrete, binder, stiffness, fatigue life, flexure

Indian Journal of Engineering, 2023, 20(53), e23ije1653

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DOI: https://doi.org/10.54905/disssi/v20i53/e23ije1653

Published: 14 June 2023