Effect of density of the polyethylene polymer on the asphalt mixtures

الملخص EN

In Iraq, for few recent years , the increasing number of vehicles and trucks with their heavy traffic loading and with the effects of other exterior factors such air temperatures effects and moisture , accumulation of these factors on the roads surfaces with an insufficient maintenance have caused distresses or deteriorations on pavement.

Polymer-modified asphalt mixtures have been used for many years to reduce the amount and severity of distress and extend the service life of hot mix asphalt (HMA) pavements.

The polymers have acceptable effects on asphalt mixes in low and high temperature due to increasing the resistance to fatigue cracking, rutting (permanent deformation) and thermal cracking.

The major objective of this research is to evaluate the effect of the density of polyethylene (PE) polymer, that one of physical properties of this locally polymer on the properties of the Hot Mix Asphalt (HMA).

One asphalt cement grade (40-50) from Al-Daurah refinery, two different types of locally available polymers (Low-Density Polyethylene LDPE and High-Density Polyethylene HDPE) have been used with three percentages for each type.

These percent's are (2, 5 and 7) % by weight of asphalt cement.

HDPE mixing at 180 C º and LDPE at 175 C º for 90 minutes by wet process with asphalt binder.

The properties of asphalt mixtures that investigated in the experimental test are Marshall volumetric properties (Marshall stability , Marshall flow) and rutting depth at (40 Cº & 50 Cº) by wheel track test to evaluate (the permanent deformations).

It can be concluded that the density of PE have significant effect on the asphalt mixtures at the optimum percent of PE (2 %) , where the increasing density increasing in Marshall Stability about (above 100 %) and reducing in rutting depth about (67 %), after compared with control mixtures .The increasing percent of HDPE & LDPE causing reducing in the asphalt mixture properties .

And concluded that HDPE modified mixtures provide better resistance against permanent deformations, because of their higher stability and stiffness, relatively lower flow.

Therefore the using of HDPE to modified asphalt mixtures give better properties to asphalt mixtures from modified mixtures by LDPE.

The effect of temperatures on the rutting depth and on the number of wheel loading passes is clearly apparent.

The samples failed at 50 Cº testing temperature faster that at 40 Cº testing temperature in which the wheel passes are decreasing to half also the rutting depth is increasing by (100 %).