###### Abstract  
The presented article studies a metakaolin-based geopolymer matrix for which two types of non-recyclable automotive glass waste (AGW) have been used as an alternative aggregate. Their composition and character, as well as their influence on the properties and structure of geopolymer composites (AGW-Gs), have been investigated by means of X-ray fluorescence and X-ray diffraction analyses, scanning electron microscopy, Fourier transform infrared spectrometry and gas chromatography/mass spectrometry. Infrared analysis has proven that the use of AGW does not affect the formation of geopolymer bonds. GC/MS analysis has revealed the presence of triethylene glycol bis(2-ethylhexanoate) in AGW and geopolymers, whose concentration varied according to the size of the fractions used. Preliminary compressive-strength tests have shown the promising potential of AGW-Gs. From the presented results, based on the study of two types of automotive glass waste, it is possible to assume that automotive glass will generally behave in the same or a similar manner in metakaolin-based geopolymer matrices and can be considered as potential alternative aggregates. The result is promising for the current search for new sources of raw materials, for ensuring resource security, for the promotion of sustainability and innovation and for meeting the needs of the growing world population while reducing dependence on limited resources. geopolymer; automotive glass waste; alternative aggregate; characterization Article  
The Synthesis and Characterization of Geopolymers Based on Metakaolin and on Automotive Glass Waste  
[PERSON], I.  
silicates) [10; 19]. A prerequisite is the presence of tetra- or penta-coordinated aluminum in the aluminosilicate precursor [7; 19]. The most extensively utilized and well-examined aluminosilicate precursors are metakaolin [20; 21], fly ash [22], different types of slag [23; 24] and various secondary or waste materials [10; 11; 25]. The precursor used significantly impacts the resulting microstructure, and obtaining the typical microstructure of the geopolymer is also associated with a precursor with a low calcium content [26; 27; 28]. The properties of geopolymers, including mechanical properties, durability, porosity, thermal insulation and others, can easily be modified by judicious selection of the matrix and/or aggregate used [11; 29; 30; 31]. In addition, geopolymers are capable of stabilizing many hazardous substances, including heavy metals or organics, in their structure [25; 32; 33]. On the other hand, the addition of organic additives to hybrid geopolymer-organic composites can help to improve their flexibility, tensile strength and overall durability [34]. Glass waste, a byproduct of various industries and municipal recycling programs, can be incorporated into geopolymer formulations as a partial or complete replacement for traditional precursors or aggregates [35; 36]. Moreover, GW can be used in the preparation of alkaline activators [36; 37]. The finely ground glass particles contribute supplementary sources of silica and alumina, enhancing the geopolymerization process. It has been demonstrated that GW serves as a feasible alternative to the commercial sodium silicate hydrates (commonly known as water glass) typically utilized in the activation of aluminosilicate materials like fly ash for geopolymer preparation [38]. The study by [PERSON] et al. has proven that sodium water glass derived from glass waste and rice husk ash can serve as viable alternative alkaline solutions in the production of metakaolin-based geopolymer binders [39]. [PERSON] and [PERSON] have reached similar conclusions regarding alkali-activated slag (AAS) [40]. They found that solutions obtained by processing GW lead to the formation of compounds and microstructures similar to those observed for AAS prepared using water glass [40].