Improvement of Asphalt and HMA Properties and Characteristics by Using Additives

Abstract

Highways pavements in Sudan are exposed to rutting and humidity making it susceptible to pavement destruction for being exposed to heavy loads on the roads. Scientists and Engineers are constantly trying to improve performance of asphalt concrete pavements by modifying the asphalt binder. Polymer-modified asphalt mixtures have been used for many years to reduce the amount of distresses severity and extend the service life of hot mix asphalt (HMA) pavements. Polymers have efficient effects on asphalt mix at low and high temperature by increasing resistance to fatigue cracking, rutting and thermal cracking. The major objective of this research is to improve and evaluate the effect of polymer on the properties of asphalt and hot mix asphalt (HMA). The type of asphalt cement used in the study was grade (60-70) with one type of polymer (Polyethylene high-density) different percentages ranging from 0 to 9 % in cement by weight of asphalt cement. The study includes Marshall mix design tests by experimental preparing hot mix asphalt mixtures. Laboratory work showed that all polymer-modified mixtures have better stability, flow and significant improvement on physical properties and asphalt characteristics for more better than control the mixture. Results showed that stability and flow values increased by adding polymer polyethylene to the asphalt mixture. Further, it was shown that bulk specific gravity is semi-static by adding amount of polyethylene. However, adding large amounts of polyethylene led to decrease in the degree of penetration, increase in flash and fire points as well as increasing softening point. It was concluded that small particle sizes of polyethylene high density result in better pavement properties. In general, addition of 6% polyethylene to asphalt mixtures showed better improvement on performance properties of the mixes. Six percent polymer was referred to as the optimum polymer content.