Process for preparing bitumen-polymer compositions, application of these compositions of the obtention of coverings and mother solution of polymer usable for the obtention of the said compositions

A process for the preparation of a bitumen-polymer composition which comprises:

• (a) contacting, at a temperature between 130.degree. C. and 230.degree. and under stirring, from 80% to 95% by weight of a bitumen with 20% to 5% by weight of a mother solution, which consists of a solution of a styrene/conjugated diene copolymer and a polysulfide in a solvent consisting of a hydrocarbon oil having a distillation range between 100.degree. C. and 450.degree. C. at atmospheric pressure and contains, by weight of the solvent, from 10% to 35% copolymer and 0.5% to 5% polysulfide, said polysulfide having the formula:
• R.sub.1 --(S).sub.m --R--(S).sub.m)R.sub.2
• wherein R.sub.1 and R.sub.2 are each independently a C.sub.1 to C.sub.20 saturated monovalent hydrocarbon radical or a C.sub.1 to C.sub.20 unsaturated monovalent hydrocarbon radical or R.sub.1 and R.sub.2 can be linked to form a C.sub.1 to C.sub.20 saturated divalent hydrocarbon radical or a C.sub.1 to C.sub.20 unsaturated divalent hydrocarbon radical, R is a C.sub.1 to C.sub.20 saturated divalent hydrocarbon radical or a C.sub.1 to C.sub.20 unsaturated divalent hydrocarbon radical, (S).sub.m is a divalent group of m sulfur atoms wherein m can be different for each group and represents a whole number of from 1 to about 6 with at least m in one group being at least 2 and x is a whole number ranging from 0 to 10;
• and
• (b) maintaining the thus obtained mixture, under stirring, at a temperature of from about 130.degree. C. to about 230.degree. C. for period of at least 15 minutes to form the bitumen-polymer composition.