Abstract: This process for obtaining bitumens containing at least one elastomer comprises two steps according to which, in the first step, a homogeneous dispersion is prepared consisting of elastomer and of selected bitumen containing a low percentage of saturated products and of asphaltenes by blending the said elastomer and the said bitumen until a master solution containing a high concentration of elastomer is obtained and, in the second step, the said master solution is diluted with a roadmaking bitumen until a homogeneous product is obtained in the form of an elastomeric bitumen.

Abstract: The bituminous mixtures for roads consist in a granular composition basically containing hard rock aggregate and a binder composed of very hard bitumens and possible additives and used in an amount corresponding to a corrected richness modulus .kappa. within the range of 3.8 to 4.5 in accordance with the relation: ##EQU1## .SIGMA.=conventional specific surface-area of the aggregate=0.25 G+2.3 S+12s+135f, in m.sup.2 /kg with the proportions by weightG representing the percentage of particles larger than 6 mmS representing the percentage of particles ranging from 6 to 0.315 mms representing the percentage of particles ranging from 0.315 to 0.08 mmf representing the percentage of particles smaller than 0.08 mmK=corrected richness modulus.alpha.=corrective coefficient intended to take into account the mass per unit volume of the aggregate, .alpha. being equal to 2.65/mass per unit volume of the aggregate.