Bitumen/polymer composition having improved low-temperature mechanical properties

A bitumen/polymer composition comprising:

• bitumen,
• an elastomer selected from the group consisting of random copolymers and block copolymers of styrene and of a conjugated diene,
• a sulfur-donating coupling agent, and
• between 0.05% and 15% by weight of an olefinic polymer adjuvant selected from the group consisting of random terpolymers and block terpolymers of ethylene, of a monomer A chosen from vinyl acetate and C1 to C6 alkyl acrylates or methacrylates, and of a monomer B chosen from glycidyl acrylate and glycidyl methacrylate, comprising from 0.5% to 40% by weight of units resulting from the monomer A and from 0.5% to 15% by weight of units resulting from the monomer B, the remainder being formed of units resulting from the ethylene,
• wherein the bitumen comprises at least:
• at least one first bitumen base having an intrinsic stability S of greater than 4.0 and a degree of peptization Sa of greater than 0.70, and
• from 24% to less than or equal to 50% by weight of at least one second bitumen base having an intrinsic stability S of less than or equal to 2.50 and a degree of peptization Sa of less than or equal to 0.60,
• the percentages being given by weight with respect to a total weight of the composition and said values S and Sa being measured according to the standard ASTM D 7157-12.