Abstract
Fatigue cracking is an essential problem of asphalt concrete that contributes to pavement damage. Although stone matrix asphalt (SMA) has significantly provided resistance to rutting failure, its resistance to fatigue failure is yet to be fully addressed. The aim of this study is to evaluate the effect of crumb rubber modifier (CRM) on stiffness and fatigue properties of SMA mixtures at optimum binder content, using four different modification levels, namely, 6%, 8%, 10%, and 12% CRM by weight of the bitumen. The testing undertaken on the asphalt mix comprises the dynamic stiffness (indirect tensile test), dynamic creep (repeated load creep), and fatigue test (indirect tensile fatigue test) at temperature of 25°C. The indirect tensile fatigue test was conducted at three different stress levels (200, 300, and 400 kPa). Experimental results indicate that CRM-reinforced SMA mixtures exhibit significantly higher fatigue life compared to the mixtures without CRM. Further, higher correlation coefficient was obtained between the fatigue life and resilient modulus as compared to permanent strain; thus resilient modulus might be a more reliable indicator in evaluating the fatigue life of asphalt mixture.
Highlights
The design of asphalt concrete mixture involves the selection and proportioning of materials to obtain the desired properties in the finished product
These can be achieved by increasing the bitumen content of the mix; such attempt may have an adverse effect on the mix stability
Since there are only a limited number of studies that investigate the fatigue life of stone matrix asphalt (SMA) mixtures using bitumen modified with waste materials, the main aim of the current study is to investigate the fatigue properties of SMA mixtures reinforced with waste tyre rubber
Summary
The design of asphalt concrete mixture involves the selection and proportioning of materials to obtain the desired properties in the finished product. Moving loads that generate alternating compressive and tensile flexural stresses on both upper and lower surfaces can cause pavement’s fatigue cracks and failures. It generally appears in the form of alligator or map cracking that is initially confined to localized zones and spreads at an increasing rate [2]. The resistance of asphalt mixtures to cracking is essentially dependent upon its tensile strength and extensibility characteristics These can be achieved by increasing the bitumen content of the mix; such attempt may have an adverse effect on the mix stability. The use of softer bitumen can improve the mix flexibility, but this may be achieved at the expense of the tensile strength and stability of the mix
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