Process for manufacturing a waterproofing membrane

A process for manufacturing a waterproofing membrane comprising:

• a preparation of a composition comprising an acrylic polymer and titanium dioxide dispersed in a solvent;
• coating a reinforcement layer by application of said composition on one side of the reinforcement layer;
• an evaporation of said solvent;
• having the coated reinforcement layer dried;
• and
• an application of a bituminous mass on another side of said reinforcement layer,
• characterized in that, during the preparation of the composition, the acrylic polymer and the titanium dioxide are dispersed in a solvent chosen in the group consisting of a solvent other than water or water wherein the acrylic polymer, the titanium dioxide and additives, in particular a thickening agent, are mixed with cristobalite.