## 1 Introduction
Such treatment harms the environment due to the non-biodegradable character of the glass, and it occupies valuable land. Therefore, an alternative use of waste glass is increasingly sought after. In the production of cement-based building materials, the leading direction is using recycled waste glass (WG) as a fine aggregate [29]. The use of WG improves the fluidity of geopolymer mortars because of the low water absorption and smooth surface of WG grains [30; 31]. Numerous previous investigations [32; 33; 34; 35] have demonstrated that the smooth surface of WG particles worsens the mechanical performance of cement-geopolymer mortar and concrete. Using WG as a fine aggregate diminished the geopolymer mortar's sorption [36] and improved the chloride resistance [28; 31]. Additionally, including WG decreased the high drying shrinkage of the cement mortar [37]. The thermal conductivity of geopolymer mortar has been decreased by using WG as an aggregate due to its own low thermal conductivity [36]. However, because most waste glass from the food industry contains a three-component sodium-calcium-silicate system, harmful alkali-silica reactions (ASRs) can occur in alkaline environments, like geopolymer or cement [38]. It was found in [39] that the geopolymer binder is less exposed to ASR degradation than the cement binder due to calcium deficiency. As demonstrated in [40], a finely ground WG can act as an alternative for the fine aggregate in geopolymers based on FA or GGBFS, because fine glass particles increase the matrix alkalinity, which leads to a broader range of dissolution and reactions close to the aggregate grains. The research presented in [41] has shown that the mixture's fluidity improved with growing WG content when using WG as a partial substituent for the fine aggregate. However, at WG content higher than 22.5%, a decrease in the compressive strength was noted. In turn, the studies presented in [42] have demonstrated that using WG as a partial replacement for the fine aggregate significantly improves the thermo-insulating ability and fire-proof performance of the geopolymer mortar based on FA. Using WG as a coarse aggregate was described in [43]. The 28-day compressive and tensile strength of the geopolymer concrete based on FA was investigated. The coarse aggregate was substituted with the waste glass by 10% to 40%. A downfall of the compressive strength was observed as the share of the recycled waste glass increased in the coarse aggregate. The research presented in [44] shows that WG can effectively replace up to 50% of the coarse aggregate without a significant change in the strength. The investigations aimed to obtain geopolymer based only on waste binders, with mechanical performance similar to that of ordinary cement mortar. The fly ash obtained from a Polish power plant was used as the main alkali-activated binder. Broken glass from a refuse site in Szczecin was employed to improve the geopolymer's mechanical properties. The tests showed the possibility of using waste glass to improve the geopolymer mortar's mechanical performance, particularly its compressive strength. Substituting 10% of FA with WG brought about more than a fourfold increase in the compressive strength and more than a twofold increase in the flexural strength. The compressive strength of all specimens containing WG was above 35 MPa and was similar to the strength of the mortars containing class 32.5 cement [45].