Viscosity properties of bimodal bitumen emulsions: new approach

The emulsions used in the manufacture of half warm asphat should contain very little water in their formulation. Conventional monomodal emulsions have a maximum dispersed phase concentration, ϕ, of 0.69. Recent research in this field is focused on the development of concentrated emulsions, ϕ = 0.70-0.74, or highly concentrated emulsions, ϕ >0.74. The concentrated or highly concentrated emulsions have little water in their formulation, <30%, but consequently have very high viscosities. This article summarizes the main conclusions related with the design, formulation and viscosity of bimodal concentrated bitumen emulsions. To formulate a bimodal emulsion is necessary to firstly manufacture two monomodal emulsion with a controlled drop size distribution from 1 and 5 μm respectively. These emulsions should be prepared with a system able to control the final drop size. In this study we have used the HIPR (High Internal Phase Ratio) procedure. The emulsions formulated in this paper are characterized by having viscosities up to ten times lower than their small monomodal size counterparts.