Effects of high density polyethylene on the permanent deformation of asphalt concrete

Abstract

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This paper reports an investigation about the effect of high density polyethylene (HDPE) in powder form as a bitumen modifier on the permanent deformation of asphalt concrete using Marshall design parameters and creep behaviour. The parameters assessed are the compacted mix density, the percentage of air voids in the mixture, the percentage of void in the mineral aggregate, the percentage of voids filled with bitumen, Marshall stability and flow and also Marshall quotient (MQ), axial strain and stiffness modulus. It is also investigated the effect of HDPE on some physical properties such as penetration, softening point and ductility. Bitumen is mixed with the HDPE at 1-4% by weight of bitumen at 185°C for 60 min. duration using a high shear mixer. Marshall samples prepared with the HDPE modified binder provide the specification limits. The addition of 3% HDPE, results in an increase of 57% in Marshall quotient. In addition, it has been observed that the use of 2% HDPE decreased the permanent strain by 34% and increased the creep stiffness by 52%. The creep recovery values of the asphalt concrete with HDPE after 15 min have been found to be higher than control mixtures. It can be concluded that HDPE modified asphaltic binders provide better resistance against permanent deformation, because of their higher stability and stiffness, relatively lower flow. As a result, HDPE modified asphaltic binders are considered to be very useful in mitigating permanent deformation in hot climate regions.

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