Abstract
The properties of asphalt modified by styrene–butadiene–styrene, polyvinyl acetate and waste crumb rubber separately in a wide range of polymer loadings were studied in this paper. In analysing the relationship between polymer loading and modified asphalt properties, we found that the ductility of polymer modified asphalt measured at 5°C exhibited a percolation phenomenon, that is, as the loading of polymer exceeded a critical value, the ductility of modified asphalt changed abruptly. Furthermore, a percolation threshold differential existed. A rubber processing analyser, an optical microscope and a fluorescence microscope were used to characterise the microstructure of polymer modified asphalt and validate the occurrence of a polymer network in modified asphalt as a function of polymer loading. The percolation phenomenon of polymer modified asphalt was found to be associated with the polymer network in modified asphalt and can be well explained by the percolation mechanism of rubber toughened plastics.
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