Abstract: A porous silicate granular material, especially as aggregate for the production of construction materials such as lightweight concrete, mortar or heat-insulating plaster containing glass and a glassy crystalline component comprising 45 to 85 wt. % SiO2, 5 to 20 wt. % alkali oxide, 5 to 30 wt. % alkaline earth oxide and 2 to 30 wt. % of other oxides such as Al2 O3 and/or Fe2O3. The glassy crystalline component accounts for 5 to 75 wt. % of the granular material. The glassy crystalline component of the granular material is a sinter reaction product. There is also a method of producing such a granular material in which the mixture is agglomerated at a temperature of 20° C. to 150° C. at normal pressure with the water vapour partial pressure being adjusted, selected or controlled as a function of time-temperature and carbon dioxide being excluded or admitted, whereby the admission of carbon dioxide is controlled by adjusting or selecting the carbon dioxide partial pressure.