Bituminous mixtures with a high polymer content

Method for preparing mixtures consisting of bitumen, thermoplastic polymer and wax, wherein the polymer is in amounts in the range from 5 to 30% by weight with respect to the weight of the mixture made up of bitumen and polymer, and the wax is in amounts in the range from 4.7 to 16.7% by weight with respect to the weight of the total mixture, which consists of reacting a concentrated mixture (A), stable at storage, containing bitumen and thermoplastic polymer in the range of from 5 to 30% by weight, with a hydrocarbon wax containing a number of carbon atoms in the range from 40 to 100 and having a melting temperature in the range from 70° C. to 120° C., in weight ratio between mixture (A) and wax in the range from 100:5 to 100:20, at a temperature in the range from 160 to 200° C. and for a time ranging from 15 minutes to 7 hours, wherein said mixture A is obtained by reacting a bituminous product having;

• a total asphaltenes, resins, saturates and aromatics content such to meet the requirement that the Ic value be in the range from 0.200 to 0.270 in the expression:
• Ic=(C7+C5+S)/(A+R)
• where:
• C7=concentration of alsphaltenes precipitated with n-heptane, in % by weight;
• C5=concentration of alsphaltenes precipitated with n-pentane, in % by weight;
• S=concentration of saturates, in % by weight;
• A=concentration of aromatics, in % by weight;
• R=concentration of resins, in % by weight,
• at a temperature ranging from 160° C. to 200° C. and for a time ranging from 15 minutes to 7 hours with a thermoplastic polymer, in weight ratio between bitumen and polymer ranging from 70:30 to 95:5, the thermoplastic polymer being a block copolymer between vinylbenzenes and conjugated dienes with radial structure, whose general formula is
• X(A−B)m
• where A represents a block obtained from monomers of the vinyl-aromatic type, B is a block obtained from diene monomers, X is a radical derived from a coupling agent and m varies from 3 to 5.