Evaluation of properties of energy-efficient geopolymer cellular concrete containing basic oxygen furnace slag aggregate

In north-western Kazakhstan, there is a higher demand for energy-efficient construction materials such as cellular concrete in the construction industry due to severe weather conditions. Moreover, construction industries in Kazakhstan are looking into developing new construction materials utilizing industrial by-products. Unlike blast furnace slag (BFS), utilization of basic oxygen furnace slag (BOFS) is limited due to its chemical composition and volumetric instability mainly caused by f-CaO and f-MgO. This study developed a total of nine energy-efficient geopolymer mixtures (3-normal geopolymer mixture and 6-geopolymer cellular concrete). Mix design variables included a partial substitution of river sand (RS) with BOFS aggregate (0%, 50%, and 100%) and three different percentages of a foaming agent (0%, 25%, and 50%). The properties of geopolymer mixtures were evaluated in terms of compressive strength, hardened density, expansion behavior, and thermal conductivity. Test results presented that replacing RS with 50% BOFS aggregates decreased compressive strength, while replacing sand with 100% BOFS aggregate led to increasing the strength regardless of the geopolymer mixture type. Geopolymer cellular concrete had lower compressive strength and thermal conductivity compared to the normal geopolymer mixture due to a higher porous cellularity structure and satisfied the threshold value of expansion due to converting f-CaO and f-MgO to CaSiO3 and MgSiO3 and absorbing the expansion stress by cellular structure.