Influence of fineness of glass cullet grinding on the structure and properties of porous glass ceramic materials

This research was aimed at establishing the effect of fineness of glass cullet grinding on the properties of porous glass ceramic materials obtained using open-hearth furnace slag as a gas-forming agent. Firing of the samples was carried out at the temperature of 7500С. For the samples under study, the volumetric weight and compressive strength were determined, the swelling coefficients were calculated, and the types of structure were analyzed, which depend on the average diameter of the predominant pores. It was found that the average pore size increased and the structure of the samples changed from fine (0.5 mm) to medium-porous (2–3 mm) with an increase in the specific surface of cullet. At the same time, there was a decrease in the volumetric weight of the samples from 500 kg m–3 to 325 kg m–3 and, accordingly, a decrease in the compressive strength limit from 6.76 MPa to 2.59 MPa. It was determined that it is necessary to use cullet with a specific surface area of at least 290 m2 kg–1 in order to obtain materials with a uniform fine- and medium-porous structure (average pore size of up to 1 mm). In the case of using cullet with a specific surface of 320 m2 kg–1, it is possible to obtain material having swelling coefficient of 3.98, volumetric weight of 376 kg m–3 and compressive strength of 3.53 MPa. A further increase in fineness of cullet grinding increases production costs and allows obtaining materials with lower volumetric weight and strength and with a pore size of up to 2–3 mm.