Bitumen emulsions formulation and destabilisation process relationship: influence of salts addition
Résumé
To simulate ionic species release from hydrolysis reactions when bitumen emulsions come into contact with gravel, electrolyte solutions have been added to cationic emulsions and their impact on emulsions stability has been tested. In order to understand how the different parameters (oils viscosity, oils and electrolytes nature) influence the emulsion destabilisation, which included a gelation process, different materials have been used: two bitumen from different origins as well as two silicone oils with different viscosities, acting as model oils to simplify the system. According to cationic emulsifier, a quaternary ammonium salt was used. The different emulsions have been studied. Macroscopic and microscopic observations as well as size distribution measurements have been performed to evaluate the emulsion destabilisation. Results obtained show relationships between emulsion formulation and destabilisation evolution (gelation process included) of the materials studied. Phenomena observed could be interpreted by well-known mechanisms such as flocculation and coalescence. Moreover, it will be discussed how the coalescence and relaxation shape kinetics, probably due to salt and emulsion formulation, affect the gelation phenomenon.