[01] Saad Issa Sarsam, Department of Civil Engineering, College of Engineering, University of Baghdad, Baghdad, Iraq. [02] Sara Ali Jasim, Department of Highway and Transportation, University of Al Mustansiria, Baghdad, Iraq.

The asphalt cement is obtained as a byproduct through the distillation process of crude oil, it requires further processing to control its constituents and quality. In Iraq, the processing units are out of order due to aging and lack of maintenance, and the produced asphalt cement does not match the standard specification required for paving work. One of the existing remedy process is to go for modified asphalt cement, which can be prepared by the addition of certain additives. The preparation method of modified asphalt cement has a great influence on its quality. In this work, asphalt cement of 44 penetration grade was obtained from Dora refinery, south of Baghdad, the asphalt cement had experienced physical and rheological properties determination. Asphalt cement was then digested with three types of modifiers, scrap tire rubber, Styrene-butadiene-styrene (SBS) and low density Polyethylene (LDPE). A cooking pressure vessel of 6 liters capacity was implemented throughout the preparation process of modified asphalt cement. The mixture was subjected to four mixing periods (10, 20, 30 and 50) minutes and a temperature of 130°C and the pressure applied by the vessel was maintained to 1bar (15 Psi). The modified asphalt cement obtained was subjected to physical and rheological properties determination, and the test results have been analyzed and compared. It was concluded that the controlled heat and pressure and mixing period have a various positive or negative impacts on the overall properties of modified asphalt cement.

Modified Asphalt Cement, Mixing Temperature, Pressure, Rheology, SBS, LDPE, Scrap Tire Rubber

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