A mixture comprising: T1) from 99 wt% to 75 wt% of bitumen, and T2) from 1 wt% to 25 wt% of polymer composition comprising the following components, A) 5-35% by weight of a propylene homopolymer or a propylene ethylene copolymer containing 90% by weight or more of propylene units; component A) containing 10.0 % by weight or less of a fraction soluble in xylene at 25°C (XSa), both the amount of propylene units and of the fraction XS A being referred to the weight of A); B) 20-50% by weight; of a copolymer of ethylene and a C 3 -C 8 alpha-olefin containing from 1.0 % to 20.0 % by weight of alpha-olefin units and containing 25.0 % by weight or less; of a fraction soluble in xylene at 25°C (XS B), both the amount of alpha-olefin units and of the fraction XS B being referred to the weight of; and C) 30-60% by weight of a copolymer of ethylene and propylene containing from 25.0 % to 75.0 % by weight of ethylene units and containing from 40.0 % to 95.0% by weight of a fraction soluble in xylene at 25°C (XSc), both the amount of ethylene units and of the fraction XSc being referred to the weight of; the amounts of, and being referred to the total weight of + +, the sum of the amount of + + being 100; the amounts, wt%, of T1 +T2 being 100 wt%. T1) from 99 wt% to 75 wt% of bitumen, and T2) from 1 wt% to 25 wt% of polymer composition comprising the following components, A) 5-35% by weight of a propylene homopolymer or a propylene ethylene copolymer containing 90% by weight or more of propylene units; component A) containing 10.0 % by weight or less of a fraction soluble in xylene at 25°C (XSa), both the amount of propylene units and of the fraction XS A being referred to the weight of A); B) 20-50% by weight; of a copolymer of ethylene and a C 3 -C 8 alpha-olefin containing from 1.0 % to 20.0 % by weight of alpha-olefin units and containing 25.0 % by weight or less; of a fraction soluble in xylene at 25°C (XS B), both the amount of alpha-olefin units and of the fraction XS B being referred to the weight of; and C) 30-60% by weight of a copolymer of ethylene and propylene containing from 25.0 % to 75.0 % by weight of ethylene units and containing from 40.0 % to 95.0% by weight of a fraction soluble in xylene at 25°C (XSc), both the amount of ethylene units and of the fraction XSc being referred to the weight of; A) 5-35% by weight of a propylene homopolymer or a propylene ethylene copolymer containing 90% by weight or more of propylene units; component A) containing 10.0 % by weight or less of a fraction soluble in xylene at 25°C (XSa), both the amount of propylene units and of the fraction XS A being referred to the weight of A); B) 20-50% by weight; of a copolymer of ethylene and a C 3 -C 8 alpha-olefin containing from 1.0 % to 20.0 % by weight of alpha-olefin units and containing 25.0 % by weight or less; of a fraction soluble in xylene at 25°C (XS B), both the amount of alpha-olefin units and of the fraction XS B being referred to the weight of; and C) 30-60% by weight of a copolymer of ethylene and propylene containing from 25.0 % to 75.0 % by weight of ethylene units and containing from 40.0 % to 95.0% by weight of a fraction soluble in xylene at 25°C (XSc), both the amount of ethylene units and of the fraction XSc being referred to the weight of; the amounts of, and being referred to the total weight of + +, the sum of the amount of + + being 100; the amounts, wt%, of T1 +T2 being 100 wt%.