Due to high expenditures, maintenance of road networks has always been one of the main concerns of pavement engineers. Effective use of Nano materials in industry, was a good reason for authors to study the capability of these kinds of materials in order to increase the service life of asphalt pavements. Considering the fact that applying Nano clay in polymers, modifies polymers characteristics e.g. stiffness, tensile strength, thermal stability, increasing flash point and resistance against moisture and vapor, also as bitumen is a thermoplastic material, the bitumen was modified by adding 20% nano clay and tested for increasing the fatigue life of asphalt pavements. The effect of nano clay additive on performance of flexible pavements is investigated through the repeated constant stress, in indirect tensile test for the core samples prepared by conventional mix and asphalt mixed with 2% of nano clay in four stress levels from 200 – 500 KPa (Steps of 100). The primary results indicated that nano core samples have almost double or even more fatigue lives in most of stress levels with less variability than conventional ones.
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