Effect of natural sand percentages on fatigue life of asphalt concrete mixture

الملخص EN

The design of a flexible pavement requires the knowledge of the material properties which are characterized by stiffness and fatigue resistance.

The fatigue resistance relates the number of load cycles to failure with the strain level applied to the asphalt mixture.

The main objective of this research is the evaluation of the fatigue life of asphalt mixtures by using two types of fine aggregate having different percentages.

In this study, two types of fine aggregate were used natural sand (desert sand) and crushed sand.

The crushed sand was replaced by natural sand (desert sand) with different percentages (0%, 25%, 75% and 100%) by the weight of the sand (passing sieve No.8 and retained on sieve No.200) and one type of binder (40/50) penetration from Al-Daurah refinery.

The samples of beams were tested by four point bending beam fatigue test at the control strain mode (250, 500 and 750) microstrain while the loading frequency (5Hz) and testing temperature (20oC) according to (AASHTO T321).

The experimental work showed that fatigue life (Nf) and initial flexural stiffness increased when control strain decreased for asphalt mixtures.

Acceptable fatigue life at 750 microstrain was obtained with asphalt concrete mixtures containing 100% crushed sand as well as asphalt concrete contained 25% natural sand.

The asphalt concrete contained 100% and 75% of natural sand exhibited high fatigue life at low level of microstrain (250).

The main conclusion of this study found that best proportion of natural sand to be added to an asphaltic concrete mixture is falling within the range (0% and 25%) by weight of fraction (passing No.8 and retained on No.200) sieve