Moreover, PET fibres in concrete minimise the prevalence of cracks and reduce its susceptibility to brittle fractures [23]. Glass stands as the predominantly used packaging material, producing waste volumes parallel to plastics. Eurostat data reveal that between 2009 and 2020, glass waste saw a 13.5% increase, amounting to 15.2 million tonnes, whereas plastic packaging waste rose by 26.7%, equalling 15.5 million tonnes during the same timespan [24]. The 2020 recycling rate for glass packaging was 76%, marking a 13.8% increase since 2006 [25]. Waste glass is remelted in smelting furnaces into glass mass, from which new products are formed. Crushed into finer fractions, waste glass can serve as an ecological substitute for cement, aiding in the reduction of CO\({}_{2}\) emissions; the manufacturing of one tonne of cement yields 0.9 tonnes of CO\({}_{2}\) emissions. Various studies support the notion that substituting approximately 10-20% of cement with glass powder results in concrete possessing superior strength compared to mixes devoid of this additive [26; 27; 28]. Employing glass in concrete as a supplementary cementitious material (SCM), without compromising its strength, mandates the meticulous selection of its quantity and granularity. Depending on several factors including the alkalinity of the pore solution, calcium content, and the particle size of the glass, the dissolved silica may repolymerise into an expansive ASR gel, form calcium silicate hydrate (C-S-H) phases, or yield both products [29]. It has been demonstrated that finely ground glass exhibits pozzolanic behaviour, with its pozzolanic properties diminishing as the particle size increases [27]. Conversely, when glass partially replaces fine or coarse aggregates, it exhibits alkali-silica reactions (ASR), necessitating the use of low alkaline cement and mineral additives to mitigate the risk of ASR occurrence [30; 31]. Appropriately quantified glass dust in concrete can shield it from the detrimental reactions of aggregates with alkalis, displaying a resistance to chloride corrosion comparable to that of concrete incorporated with fly ash [32; 33]. The imperative to recycle waste materials remains paramount, which, beyond its ecological dimension and commitment to environmental care, also bears significant economic rationality. To curtail the amount of waste sent to landfill, the European Union promulgated Directive 2018/852 established mandated thresholds for the recovery and recycling pertinent to the management of packaging and associated waste. According to this Directive, member states are obligated to recycle 65% of packaging waste by 2025; this includes 50% of plastics and 70% of glass [34]. Numerous studies presented at the EATA 2023 conference indicate a strong need to utilise plastomers, including PET, for the production of asphalt mixtures. The dry method, which involves introducing PET flakes into the recycled mixture, is used to build bounded road bases with a cement binder. In work [35], it was concluded that there is a lack of studies on the effects of the PET content on concrete behaviour. However, it was indicated that the possible optimal replacement of the aggregate by PET ratio is 1-5%. In turn in work [36], it has been suggested that replacing sand with waste PET particles positively affects the strength-related values of concrete specimens as long as the replacement ratio is less than 15%. Therefore, the application of PET as an aggregate substitute has environmental and practical meaning as well. The objective of this research is to explore the feasibility of utilising waste from PET and glass packaging as an additive for cement mortar. Insights garnered from the literature review ascertain that PET can serve as a partial aggregate substitute and glass pow-der as a partial cement substitute. A discernible void is evident in both the national and international literature regarding the combined impacts of these additives on the properties of both fresh and hardened mortar.