Author : Farag Khodary

The conventional bitumen has a limited capacity under wide range of loads and temperature which occur over the life of a pavement. Therefore, conventional bitumen needs to be modified to face the heavy loads and weather change. Number of materials used to improve the properties of bitumen and asphalt properties such as polymers and rubber. And with the considerable increase demand to get better properties of asphalt concrete mixtures nano scale material ware used as asphalt modifier. One of the most important properties of nano scale material is surface to volume ratio. The conventional bitumen used in this research was AC (60/70) penetration grade, modified with 5% styrene–butadiene–styrene as well as nanoclay (nCL) at four different modification levels namely 2%, 4%, 6% and 8% by weight of the bitumen. Morphology and structural of the prepared materials were investigated using spectroscopic techniques such as Transmission electron microscope (TEM) and Scan electron microscope (SEM). Penetration and softening point were used to evaluate the modified bitumen as well indirect tensile strength test and fatigue test were carried out to characterize the properties modified and unmodified asphalt concrete mixtures. Based on the results, it was found that using (SBS@Clay) nanocomposite improves both penetration and softening point of all modified bitumen. Tensile strength for modified mixtures with 5% SBS and 6% nanoclay is higher than unmodified mixtures by nearly three times. Fatigue life of (SBS@Clay) modified mixtures equals to 3.4 times higher than unmodified bitumen.

Keywords: Modified bitumen, Tensile strength, nano-clay, styrene–butadiene–styrene , fatigue , asphalt concrete mixtures.

Article published in International Journal of Current Engineering and Technology, Vol.5, No.2 (April-2015)