BITUMEN IN COLLOID SCIENCE - A CHEMICAL, STRUCTURAL AND RHEOLOGICAL APPROACH

The present study gives a new understanding about bitumen's colloidal behavior, related to its chemical composition, microscopic structure a nd rheological properties. Bitumens possess a strong temperature depen dence of rheological properties, governed by the interaction of the in dividual constituents. Much importance is given to the colloidal index of the bitumen, based on the ratio of the four main chemical componen ts (asphaltenes, resins, aromatics, saturates). Increasing one of thes e constituents fundamentally changes the structure and the theological behavior of bitumen. Therefore, a gel bitumen contains high asphalten e/resin concentrations, leading to a network structure with high rigid ity and elasticity (high IGI, low delta), whereas a sol bitumen posse sses a high resin/asphaltene ratio, forming domains of coherent asphal tene micelles which lead to a good time-temperature equivalence in the Black space but also high viscous behavior. (C) 1998 Elsevier Science Ltd. All rights reserved.