Effect of aggregate nature on the fatigue-cracking behavior of asphalt mixes

Fatigue cracking in asphalt mixes is one of the most common road pavement distresses. When mixes are designed in the laboratory, it is very important to select the most suitable materials to ensure a good performance against this phenomenon. The types of binder and mortar strongly influence mix cohesion by providing tensile and shear strength. The mineral skeleton supplies it with compressive strength and bearing capacity. In this sense, the grading curve and shape of the aggregate affect crack growth (because of the internal friction), whereas the nature of the aggregate plays an important role in mix behavior (because of its adhesion to the bitumen and its resistance to fragmentation). This paper analyzes the impact of the nature of coarse aggregate on the fatigue-cracking behavior of asphalt mixes, an aspect that until now has received little attention. The UGR–FACT test was used to evaluate the cracking behavior of two mixes by varying the load amplitude, frequency, and test temperature. The results obtained showed that the nature of the coarse aggregate has an important effect in the fatigue-cracking behavior of asphalt mixes, and could be as important as bitumen type or mineral skeleton in mix design.