Aqueous suspension of surface-reacted calcium carbonate obtainable by a process for preparing a surface-reacted calcium carbonate in an aqueous environment, the process comprising the following steps: a) providing at least one ground natural calcium carbonate (GNCC); b) providing at least one water-soluble acid; c) providing gaseous CO 2; d) contacting said GNCC of step a) with said acid of step b) and with said CO 2 of step c); characterised in that: (i) said acid(s) of step b) each having a pK a of greater than 2.5 and less than or equal to 7, when measured at 20°C, associated with the ionisation of their first available hydrogen, and a corresponding anion formed on loss of this first available hydrogen capable of forming water-soluble calcium salts and wherein said water-soluble acid(s) are selected from the group consisting of acetic acid, formic acid, propanoic acid and mixtures thereof; (ii) following contacting said acid(s) with said GNCC, at least one water-soluble salt, which in the case of a hydrogen-containing salt has a pK a of greater than 7, when measured at 20°C, associated with the ionisation of the first available hydrogen, and the salt anion of which is capable of forming water-insoluble calcium salts, is additionally provided; (iii) said water-soluble acid(s) are dosed in a total amount corresponding to from 3 x 10 4 to 10 x 10 -4 mol of hydrogen atoms in the acid/m 2 GNCC provided in step a). a) providing at least one ground natural calcium carbonate (GNCC); b) providing at least one water-soluble acid; c) providing gaseous CO 2; d) contacting said GNCC of step a) with said acid of step b) and with said CO 2 of step c); characterised in that: (i) said acid(s) of step b) each having a pK a of greater than 2.5 and less than or equal to 7, when measured at 20°C, associated with the ionisation of their first available hydrogen, and a corresponding anion formed on loss of this first available hydrogen capable of forming water-soluble calcium salts and wherein said water-soluble acid(s) are selected from the group consisting of acetic acid, formic acid, propanoic acid and mixtures thereof; (ii) following contacting said acid(s) with said GNCC, at least one water-soluble salt, which in the case of a hydrogen-containing salt has a pK a of greater than 7, when measured at 20°C, associated with the ionisation of the first available hydrogen, and the salt anion of which is capable of forming water-insoluble calcium salts, is additionally provided; (iii) said water-soluble acid(s) are dosed in a total amount corresponding to from 3 x 10 4 to 10 x 10 -4 mol of hydrogen atoms in the acid/m 2 GNCC provided in step a). (i) said acid(s) of step b) each having a pK a of greater than 2.5 and less than or equal to 7, when measured at 20°C, associated with the ionisation of their first available hydrogen, and a corresponding anion formed on loss of this first available hydrogen capable of forming water-soluble calcium salts and wherein said water-soluble acid(s) are selected from the group consisting of acetic acid, formic acid, propanoic acid and mixtures thereof; (ii) following contacting said acid(s) with said GNCC, at least one water-soluble salt, which in the case of a hydrogen-containing salt has a pK a of greater than 7, when measured at 20°C, associated with the ionisation of the first available hydrogen, and the salt anion of which is capable of forming water-insoluble calcium salts, is additionally provided; (iii) said water-soluble acid(s) are dosed in a total amount corresponding to from 3 x 10 4 to 10 x 10 -4 mol of hydrogen atoms in the acid/m 2 GNCC provided in step a).