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.