The present invention relates to glassy solids which are obtainable by carbonation of a solid glassy precursor, said glassy precursor having a SiO.sub.2 content of at least 65 wt. %. The invention further relates to a mechanochemically carbonated glassy solid and methods of its production. The invention further relates to uses of the (mechanochemically carbonated) glassy solid, for example as a filler. The invention further relates to compositions comprising the (mechanochemically carbonated) glassy solid and a further material selected from the group consisting of asphalt, cement, geopolymer, polymers and combinations thereof. The invention further relates to a method of preparing concrete.