having a grain size of 0 10 mm the binder is bitumen with a penetrability of 35 50 according to the standard nf en 1426 and drying is carried out at 130 u00b0 c when it is applied to only a first part of the granular materials and at 90 u00b0 c when it is applied to the entirety of the granular materials the proportions indicated are by mass the solid fragments are formed of 98 granular materials having a grain size of 0 10 mm and of 2 calcareous fines the 98 of 0 10 granular materials are formed of porphyry and have the following grain size distribution the 6 10 and 2 6 fractions and fines are mixed and dried at 130 u00b0 c then the 0 2 fraction is added at ambient temperature its degree of humidity being 4 then 5 6 35 50 bitumen is added at 160 u00b0 c to carry out coating the composition of solid fragments and the quantity of binder are the same as in example 1 drying is carried out on the entirety of the solid fragments whereupon 1 5 water is added in proportion by mass before carrying out coating by adding binder at 160 u00b0 c the type and distribution of grain sizes of the solid fragments and the quantity of binder are the same as in examples 1 and 2 the entirety of the solid fragments is divided homogeneously into a first part representing 65 by mass and a second part representing 35 by mass the first part is dried at 130 u00b0 c then the second part is added at ambient temperature its degree of humidity being 4 then.