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.
