Assessing the Sensitivity of the Strength Properties of Asphalt Concrete Mixture to the Variation in Asphalt Binder Content

saad sarsam

Abstract

The variationsin the asphalt cement binder content withinthe job mix formula, may exhibit a great influence on the required strength properties of asphalt concrete mixture. The present investigation deals with asphalt concrete mixtures which are usually implemented for wearing course pavement layer. The mixtures were prepared at optimum binder content of 4.8 %, and at ± 0.5 % of the optimum binder content and subjected to the short-term ageing process.Slab samples of asphalt concrete mixtureshave been prepared in the laboratory using roller compaction. Asphalt concrete beam specimens have been obtained from the roller compacted slab samples and subjected to testing for evaluation of the viscoelastic properties after practicing long-term ageing and moisture damage processes. The permanent deformation and the flexural stiffness have been evaluated by implementing the four-points bending beam test at 20 ºC environment and under constant micro-strain level of 750 and. It was noticed that higher flexural stiffness could be detected for aged or moisture damaged specimens when compared with the control mixtures. The strength properties of the asphalt concrete specimens in terms of the flexural stiffness and the resistance to permanent deformation were noticed to be highly sensitive to the variations in the asphalt binder content. However, it was revealed that a stringent control of asphalt binder content should be maintained when preparing the asphalt concrete mixture in the plant so that the physical properties of asphalt concrete throughout its service life could be enhanced.

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