Performance Modification of Saudi-Asphalt Binders

Using Local Polymers

Hamad I. Al-Abdul Wahhab, Ibrahim M. Asi

And Isam Abaker

Abstract

The Kingdom of Saudi Arabia has invested more than SR 135 billion in road construction over the past twenty-five years. Some of the roads, which have been built to the best international standards, have shown early signs of distresses due to the harsh environmental and traffic loading. This has led to an increased demand to modify asphalt binders. Different methods have been used to upgrade the properties of asphalt binders. One of the most commonly used procedures is modification by addition of polymers. In the kingdom, most of the used asphalt-polymers are imported from abroad. The main objective of this research is to modify locally produced asphalt using polymer produced by Saudi Basic Industries Company (SABIC). The study covered the asphalt binders produced in Ras Tanura refinery and the polymer produced by SABIC. Ten polymers were identified as potential asphalt modifiers based on their physical properties and chemical composition. Based on the preliminary laboratory evaluation for the melting point of these polymers, four polymers were selected for local asphalt modification which included: 1) Linear Low Density Polyethylene (LLDPE) grade M200024, 2) LLDPE grade M50026, 3) High Density Polyethylene (HDPE) grade M200056, and 4) Medium Density Polyethylene (MDPE) grade R50035. In the initial stage, required mixing time was decided based on the relation between shear loss modulus and mixing time. The optimum polymer content was selected based on Superpave binder performance grade specifications. The suitability of improvement was verified through the evaluation of permanent deformation and fatigue behavior of laboratory prepared asphalt concrete mixes. The results indicate that the rheological properties of the modified binders were improved significantly with sufficient polymer content (3%). They were also influenced by the type and content of the polymer. The aging properties of the modified binders were found to be dependent on the type of polymer. The fatigue life and resistance to permanent deformation were significantly improved due to the improvement in the rheological properties of the binders. In general, the research has shown the possibility of modifying local asphalts using SABIC polymers.