Experimental study on mode I fracture toughness of different asphalt mixtures.

Low temperature cracking is one of the main distresses observed in pavements made of hot mix asphalt mixtures. As a material property, the fracture toughness of asphalt pavements is a fundamental parameter for estimating the load bearing capacity and resistance of cracked pavements against crack growth. In this paper, the fracture toughness (K_Ic) of different and various compositions of asphalt mixtures is obtained experimentally, and the effects of asphalt characteristic specifications and its composition are investigated on the value of K_Ic. Several asphalt mixtures were prepared with three aggregate sizes, two aggregate types (limestone and siliceous), different air void percentages ranging from 3.5 to 8%, and two binders (60/70 and 85/100). Other similar work has only studied the influence of limited characteristic parameters on the low temperature fracture resistance of asphalt mixtures. Several Semi-Circular Bend (SCB) specimens subjected to three point bend loading were manufactured with different compositions and were then tested at -15°C. The experimental results showed the noticeable influence of characteristic specifications of asphalt mixtures on the value of K_Ic. Generally, the value of KIc decreases for those mixtures containing a smaller size of aggregates made of siliceous, with higher percentages of air voids and softer binder types. [ABSTRACT FROM AUTHOR]