Oily sludges are generally formed from oil residues, effluents and wastes of different stages of separation in the petroleum industry and have various and complex compositions depending on the source of production and storage conditions. In addition to reducing capacity and causing corrosion in storage tanks, these sludges will also cause environmental risks due to water and soil pollution. In this study, using physical methods, the hydrocarbon compounds in the sludge are separated from other compounds including water and solid minerals. Then by adding different percentages of separated sludge and natural bitumen to 60/70 bitumen, were formulated bitumens with different quality. The physical and chemical properties of the resulting bitumen were evaluated in the laboratory and the results show an increase in the desired quality of produced bitumen. In this paper, the surface response method (RSM) was used to optimize the bitumen production formulation.

Post-consumer waste polymers are considered as environmental pollutants that should be reused as inexpensive materials. Also, there are resources of natural bitumen in several regions of Iran that can be used to modify bitumen. The purpose of this study is to investigate the possibility of obtaining penetration grade modified bitumen from vacuum bottom residue (VB) by adding various recycled waste polymers and non-polymer materials without air blowing VB. Following this concept, natural bitumen (NB), recycled waste polyethylene (PE), recycled waste latex, crump rubber modifier (CRM) and heavy vacuum slopes (HVS) were used. The formulation of mixing blends was determined by experimental design method using design-expert V.7.16 software. It was found that 40/50, 60/70 and 85/100 grades of penetration bitumen with improved performance grades, 82-40, 70-40 and 70-40, respectively, are producible using these materials, although, decreased ductility is observed almost for all the blends. A combination of 10% natural bitumen and 5% recycled latex with VB are considered as the best blend amongst all blends. The resulting modified 60/70 grade bitumen shows improved complex modulus in comparison with neat 60/70 bitumen and consequently it has increased resistance against permanent deformation (rutting). Also, the lowered Frass breaking point of this blend (-21°C) improved its low temperature performance (PG = 70-40). Unfortunately, when the crump rubber modifier particles are not well-dispersed and fine enough in bitumen matrix, there is an unexpected decreased ductility occurred in the blends.

As a very important coating material in different applications, bitumen is a complex mixture of different chemicals. It is generally accepted that the principle of time-temperature superposition (TTS) holds for this material. In this study rheological measurements were carried out on four different bitumens. Different representations of the experimental data were examined to check failure or holding of TTS for this complex system. Due to differences in dynamics of components, discontinuities were observed in versus G* curves for all four bitumens. It was concluded that the TTS fails to be applied for the studied bitumens.

The main objective of the present study was to conduct a comparative test program on unmodified bitumen and modified bitumen containing nanoclay and assess the effects of asphalt properties on pavement performance. To meet this objective, the main targets of this study are to find out if the nanoclays alter the critical prop- erties of asphalt binder and influence the ageing and temperature sensitivity of the binder. Different tasks were performed to meet the objectives. The first task performed was studying the nanoclay modifiers at a nanoscopic level and the test performed in this area was the X ray analysis of the nanoclay modifiers. The sec- ond task was studying the influence of nanoclay modifiers on binder characteristics and the related tests performed were empirical studies of fresh (unaged) and aged bitumen types by empirical tests like penetration and softening points. Findings of the tests performed on binders proved that the cloisite-15A nanoclay modifications helped to increase the stiffness of the standard binder. This was especially true if the 4% cloisite modification was used. The nanofil-15 modification helps to improve the ageing resistance of the binder in short and long term applications. An overall conclusion from these findings is that the nanoclay modifications help to improve some characteristics of asphalt binders and asphalt mixtures, but at this level they are not at a stage to justify applications on large scales.

In the last decades, extensive research works have been devoted to bitumen and asphalt modification by using polymeric thermoplastic-elastomers. In this research a physical thermoplastic elastomer was prepared by mixing polystyrene (PS) and polybutadiene (PB) for bitumen modification purposes. These blends were introduced into bitumen for making polymer-bitumen mixtures. Then, stabilization mechanism and mechanical properties of the mixture were studied by optical microscopy and conventional tests such as: Frass test, softening point, penetration, performance grade and penetration index. The PS/PB (75/25) blend forms larger PS droplets and shows minimum stability among the blends. The co-continuous composition of PS/PB blend (27/73) is stable and PS droplets are very well dispersed and its particle sizes are the lowest. In the next step, PS/PB/SBR compatibilized blend was mixed with bitumen and than further studies were carried out. The results show that mechanical properties and elastic recovery of these blends are highly improved as compared with the former non-compatibilized blend admixtures.