A method of producing a mainly carbonate bonded article for use as a construction material by carbonation, the method comprising the steps of: - providing a granular material having a pH higher than or equal to 8.3, the granular material comprising at least one alkaline earth metal silicate phase, wherein the granular material comprises a fine fraction consisting of all the particles of the granular material having a size smaller than or equal to 500 μm, the fine fraction amounting to at least 50% by weight of the granular material, and wherein at least 10% by volume of the fine fraction has a particle size smaller than or equal to 50 μm, - compacting the granular material with a compaction pressure of at least 5 MPa to obtain a compact of the granular material, wherein the granulometry of the granular material is so selected and the compacting step is so arranged that the porosity of the compact is smaller than or equal to 37% by volume and the intrinsic permeability of the compact is at least 1·10 -12 cm 2, and - reacting the granular material in said compact with carbon dioxide in the presence of water to form at least 5% by weight of carbonates CO 3 2 − thus transforming the compact into the mainly carbonate bonded article, in which reacting step the compact, being unsaturated with moisture at the beginning of the reacting step, is put in an atmosphere comprising said carbon dioxide, wherein said atmosphere is at a temperature of at least 70°C and at a pressure of at least 0.5 MPa so that said alkaline earth metal silicate phase contributes to the formation of said carbonates, said pressure being higher than the saturated vapour pressure of water at said temperature, wherein the granular material is free of material having hydraulic binding properties or comprises at most such an amount thereof that the compressive strength of the mainly carbonate bonded article is more than two times the strength of a same compact treated in a nitrogen atmosphere which is free of carbon dioxide under same conditions as in the reacting step. - providing a granular material having a pH higher than or equal to 8.3, the granular material comprising at least one alkaline earth metal silicate phase, wherein the granular material comprises a fine fraction consisting of all the particles of the granular material having a size smaller than or equal to 500 μm, the fine fraction amounting to at least 50% by weight of the granular material, and wherein at least 10% by volume of the fine fraction has a particle size smaller than or equal to 50 μm, - compacting the granular material with a compaction pressure of at least 5 MPa to obtain a compact of the granular material, wherein the granulometry of the granular material is so selected and the compacting step is so arranged that the porosity of the compact is smaller than or equal to 37% by volume and the intrinsic permeability of the compact is at least 1·10 -12 cm 2, and - reacting the granular material in said compact with carbon dioxide in the presence of water to form at least 5% by weight of carbonates CO 3 2 − thus transforming the compact into the mainly carbonate bonded article, in which reacting step the compact, being unsaturated with moisture at the beginning of the reacting step, is put in an atmosphere comprising said carbon dioxide, wherein said atmosphere is at a temperature of at least 70°C and at a pressure of at least 0.5 MPa so that said alkaline earth metal silicate phase contributes to the formation of said carbonates, said pressure being higher than the saturated vapour pressure of water at said temperature, wherein the granular material is free of material having hydraulic binding properties or comprises at most such an amount thereof that the compressive strength of the mainly carbonate bonded article is more than two times the strength of a same compact treated in a nitrogen atmosphere which is free of carbon dioxide under same conditions as in the reacting step.