Bitumen-Organo-Clay Composites

Abstract

The physical properties and temperature susceptibility characteristics of bitumen influence pavement performance at low and high field operating temperatures. It was proven that addition of additives like polymers can influence the temperature susceptibility of asphalt cements and as a result an improvement in the performance of asphalt mixtures can be obtained in a wide temperature range. Similar to polymer nanocomposites, a number of physical properties of bitumen can successfully be enhanced when the bitumen is modified with small amount of clay on condition that the clay is dispersed at nanoscopic level. Based on the same principle as used with polymer modifications, we have carried out the modification of bitumen using organically modified and polymer compatibilized clays. Three different types of clays on the basis of polarity and one type of polymer as compatibilizer were selected for bitumen modification. The expectation with the nanoclay modified bitumen is to influence properties like rutting resistance, fatigue resistance and resistance to ageing. The main objectives of the project are to find out if the nanoclay alters the critical properties of bitumen and influences the ageing and rheology of the binder. To meet the objectives, the first task was performed to study the clay modified bitumen at nanoscopic level and therefore microscopic and x-ray analyses were performed to study the nanoclay dispersion in bitumen. The second task was to study the influence of nanoclay modifiers on bitumen characteristics and therefore the rheological studies of fresh (un-aged) and aged bitumen samples by dynamic shear rheometer (DSR); including the empirical tests such as penetration and softening point measurements were performed. The findings from the tests proved that nanoclay modification helped to increase rutting resistance (at 40OC and 60 OC) of bitumen. The modification also helped to increase the ageing resistance of bitumen. However, the nanoclay modifications were observed to negatively influence the fatigue resistance parameter of bitumen.