Régis Vincent

The weak help the strong: low-molar-mass organogelators harden bitumen.

Low-molar-mass organogelators (LMOG) can turn liquids into thermoreversible gels because they self-assemble into a fibrous network. In contrast, using the same kind of low-molar-mass additives to harden materials, which are already solidlike on their own, has been hardly exploited. We show here that simple dicarboxylic acids are very efficient low-molar-mass organogelators (LMOG) for bitumen. Indeed, they increase the range of temperature where bitumen is a solid. Moreover, the hardness and elastic modulus of bitumen at room temperature are also improved. This concept of improving the mechanical properties of a solid with an LMOG can probably be applied to other materials.

A new bituminous binder replacing oxidized bitumen in roofing applications

Thanks to its excellent properties of adhesion, the use of the oxidized bitumen as HAC goes back up to decades. However, these oxidized bitumen’s stemming from blowing processes possess a high viscosity leading to an application temperature superior of 210°C. In these conditions of applications, smokes are generated and can disturb the operator. In the objective to reduce the application temperature of these HAC, an alternative binder to oxidized bitumen for bonding applications was developed. This new product possesses similar or superior performances to those of the oxidized bitumen. It is characterized by a Ring-Ball temperature close to 100°C and a weak viscosity what allows an important reduction of the application temperature (from 40 to 90°C). This decrease improves on one hand the comfort of the teams of application by a remarkable reduction of smokes and on the other hand allows a substantial energy saving. Besides, pealing experiments showed a bonding property more successful than that observed with oxidized bitumen. Finally, an excellent creep resistance is demonstrated by rheological measurements until a temperature of 75°C under load. Consequently, a stability strengthened by this product in block during its transport and its storage is noted.