الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The use of modifiers to improve the performance of asphalt concrete mixtures has been employed in highway industry from almost the first use of hot mix asphalt. Modifiers take many different forms. Many modifiers change the properties of the asphalt binder. These modifiers include polymer, latex and many chemical additive. There are also many modifiers that change the properties of mixtures: fillers, fibers, and some polymers which do not blend with the binders. Determining how modifiers actually affect the performance of a mixture and establishing construction quality control procedures for these modifiers is extremely interesting.
In the present research attention has been paid to study the influence of recycled plastic material on both dens- graded asphalt (ACM) and gap graded asphalt (SMA). The present study has been conducted through the following stages.,
• In the first stage three kinds of recycled plastic (Polyetheylene (PE), Polyethelene Tetra phthalate (PET) and Polyvinyl Chloride (PVC)) in a predetermined concentration of 13% by weight f asphalt were tested by Marshall mix design method which was employed for designing both conventional and modified mixtures to determine the optimum asphalt content for each type of gradation and determine the best type of polymers to be used in this study.
• The main outcome of the first stage confirmed that PET was the most suitable additive taking into consideration that the optimum binder content which gave the best mechanical properties was 5.2% ( by weigh of aggregate) with PET 13% ( by asphalt weight) instead of 6% without PET for ACM , while for SMA it was 5.8% (by weight of aggregate) with PET concentration 13% (by asphalt weight) instead of 6.2% without PET.
• During he last stage PET in different concentration (11, 12, 13, 1 4 and 15%) by weight of asphalt was extensively studied to verify the ideal concentration. Evaluation of the performance was based on Marshall test, indirect tensile strength test, rutting test and bending test. These data were confirmed by BISAR computer program.
The main finding of this research was that the addition of PET to asphalt cement exhibited an improvement of mechanical properties of asphalt concrete mixtures .Furthermore, from the economic point of view, it is much less expensive than the other types .
Also, it was found that , the use of Stone Matrix Asphalt (SMA) could be very useful in resisting permanent deformation especially when used with modified asphalt binders such as PET modified asphalt.