Influence of Aging on the Properties of Waste Polymer Asphalt Binder

Abstract

Lengthening the service life of pavement had been the primary goal of road sector agencies. The severity of traffic demand that is being placed on our pavements is increasing significantly day by day. Likewise the rapid development, increase in traffic load and volume, and insufficient maintenance is leading to severe distresses of road surfaces like rutting and cracking. Thereby the high quality bitumen is inevitable to handle the above mentioned issues. The bitumen modification is one of the quality tool being used by the engineers since two decades for improvement of the service life of pavements by enhancing the pavement quality. A promising strategy that has been widely accepted for improving the pavement deficiencies, is the use of commercial polymers for asphalt binder modification. However their high cost is the major hurdle in their use, especially in the developing countries. Instead of these commercial polymers researchers are using waste plastic polymers to attain the same benefits. Their cost effectiveness and environment friendly quality is making them the most popular asphalt binder modifier all over the world. The current study aimed at studying the influence of aging on the properties of waste polymer modified asphalt binder. Two such polymers, waste PET (polyethylene terephthalate i.e. plastic bottles) and waste LDPE (low-density polyethylene i.e. plastic bags) were collected from the vicinity, than cleaned, uncapped and shredded to a size less than 0.5mm and blended separately with 60/70 penetration grade bitumen at four different concentrations (2%, 4%, 6% and 8% by weight of bitumen). Penetration, Ductility, Rotational viscosity and Ring and Ball tests were performed on the unaged modified binder samples, short term aged (using rolling thin film oven test (RTFO)) modified binder samples, and long term aged (using pressure aging vessel test (PAV)) modified binder samples. The chemical changes were studied using Fourier Transform Infrared Spectroscopy (FTIR), and morphological changes were studied using Scanning Electron Microscopy (SEM). The results showed decrease in penetration and ductility values, whereas increase in softening point and viscosity values. The sulfoxide and carbonyl index values decreased, that is the indicator of the improvement in the oxidation resistance. The results of the morphological analysis showed good compatibility of the modifiers with asphalt binder. To sum up, it could be said that the use of these non-biodegradable waste polymers is not only enhancing the properties of the binder but is saving the cost of the material as well as environment from pollution.