Study of Structure and Phase Formation During Thermal Treatment of Geopolymer Compositions Based on Mineral Waste

A comprehensive study was conducted to investigate the influence of mineral waste on the thermal stability of foamed geopolymer materials. The study's objects were steelmaking slag (SS) from the Taganrog Metallurgical Plant, drilling sludge (DS) from the Sutorminskoye oil field, and an ash and slag mixture (ASM) from the Novocherkasskaya SDPP. The utilisation of drilling sludge as an additive in the production of geopolymers has been proposed for the first time. The study involved the development of alkaline activators based on solutions of sodium and potassium silicates and their hydroxides. The samples were synthesised with varying proportions of steelmaking slag and drilling sludge, and physicochemical, mechanical and high-temperature studies were conducted to ascertain the optimal composition. X-ray phase analysis of the synthesised samples was conducted. An investigation was conducted into alterations in the phase composition of the material as a consequence of heat treatment. Proposals were hereby made for the mechanisms of the formation of new phases. The study identified an alkaline activator based on a solution of silicate and sodium hydroxide, with the introduction of 10% steelmaking slag into the component mixture, as the most effective mixture. The resultant geopolymers exhibited a density of 311 kg/m³ and an ultimate compressive strength of 1.54 MPa.