Method for producing an asphalt binder emulsion which makes it possible to control the viscosity and breaking properties of the emulsion

A process for the production of an aqueous asphalt binder emulsion with controlled viscosity and breaking properties which comprises:

• introducing a molten asphalt binder at a temperature of from 80.degree. C. to 180.degree. C. and an aqueous phase, containing at least a portion of an emulsifying system and optionally a pH adjusting agent, at a temperature of from 10.degree. C. to 90.degree. C. into an emulsifying zone (1) comprising an inlet (6) and an outlet (10) separated by a series (28 to 33) of rotor/stator shearing zones arranged in series each comprising at least one circular groove (28 to 33) formed in one face (19 to 24) of a stationary stator element (15 to 17), rigidly connected to the wall (2) of the zone (1) into which circular groove enters a series of rotor projections (37 to 42), each having, in cross-section through a plane containing the axis (18) of the groove, a shape complementary to that of the corresponding cross-section of the groove, so as to define, between each projection and the groove, a space forming a gap, the projections being rigidly connected to one of the faces of a rotor support disc (47 to 50) centered on the axis (18) of the groove and rotationally mobile around the axis, which disc is traversed by orifices (51 to 54) arranged between the axis of the groove and the projections, the grooves of two consecutive shearing zones being arranged so as to be either formed in the opposite faces (21,22) of the same stator element (16) and connected via channels (35) connecting their respective bottoms, or formed in the facing faces (22, 23) of two consecutive stator elements (16, 17) and separated by a rotor support disc (49) carrying projections (40, 41) on its two faces, the process being characterized in that there is injected into the emulsifying enclosure, via its inlet, an asphalt binder (8) in the form of a molten mass having a temperature between 80.degree. C. and 180.degree. C., and an aqueous phase (9), which contains an emulsifying system or at least one of its components, the remainder of the emulsifying system then being present in the asphalt binder, and optionally an agent for adjusting the pH of the emulsion and which has a temperature between 10.degree. C. and 90.degree. C., wherein the combined asphalt binder and aqueous phase pass into the successive shearing zones having air-gaps with a width of from 0.1 mm to 5 mm, by imposing a rotational speed on the rotor discs carrying the projections such that their peripheral speed is between 4 and 18 m/s.