Effect of different additives on fatigue behavior of asphalt mixtures

Fatigue failure is a common problem of asphaltic concrete pavements which can lead to damage. Fatigue cracking has been recognized as one of the main forms for structural damage in asphalt concrete pavements. Under the action of repeated vehicular loading, deterioration of the asphalt concrete materials in pavements, caused by the accumulation and growth of micro- and macro-cracks, gradually takes place. This paper studies the beneficial properties of modified asphalt mixtures in resistance to fatigue of mixtures with different additives of crumb rubber (CR), reclaimed rubber (RR) and styrene-butadiene-styrene SBS. Laboratory asphalt mixture samples were fabricated then compacted into slabs and sawed to beam samples. Asphalt mixture beams were tested under four point bending (4PB) universal testing machine. Stress controlled testing protocol simulates the same situation as in the pavement structure. As the stress remains constant during load cycles the measured strain increases continuously. Beam fatigue results compared to each other and results showed that modified mixtures had performed better in different conditions.