Abstract: 
The invention relates to organopolysiloxane compositions comprising (A1) resin component consisting of at least one organopolysiloxane resin consisting of units of the formula Ra(OH)b(R1O)cSiO(4abc) /2 (I), (A2) organosilicon component consisting of at least one organosilicon compound consisting of units of the formula R2 d(OH)e(R3O)fSiO(4def)/2 (II), where the radicals and indices are each as defined in claim 1, with the proviso that in formula (I) the sum of a + b + c ≤ 3, in the resin component (A1) in at least 2% of all the units of the formula (I) b ≥ 1, in the resin component (A1) in at most 10% of all the units of the formula (I) c ≥ 1, in the resin component (A1) in at most 50% of the units of the formula (I) a = 2, and the resin component (A1) has a mean molecular weight Mw (weight average) of 500 g/mol to 11 000 g/mol and a molecular weight Mn (number average) of 500 g/mol to 5000 g/mol, and the polydispersity (Mw/Mn) of the resin component (A1) is 1 to 5, the sum in formula (II) d + e + f ≤ 4, in the organosilicon component (A2) in at least 10% of all the units of the formula (II) f ≥ 1, in the organosilicon component (A2) in at most 2% of all the units of the formula (II) e ≥ 1, and in the organosilicon component (A2) in at most 50% of the units of the formula (II) having d + e + f ≤ 3 d = 2, and to processes for preparation thereof and to the use thereof, especially for production of synthetic rocks.
