The paper presents a study on the infl uence of ground waste glass cullet, introduced as a component of Portland cements in the amounts of 5% and 35% by mass, on the properties of pastes and mortars. The pozzolanic nature of the additive was confirmed – the long-term compressive strength of cement composites has incre-ased, compared to the reference sample. However, a decrease in the early compressive strength was observed. Replacing part of the Portland clinker with ground waste glass cullet resulted in the reduction of the heat of hydration. It was determined that the degree of grinding has a signifi cant impact on the activity of waste glass cullet – in the case of the cullet ground to 5000 cm2/g, the beginning of the pozzolanic reaction was observed after 7 days, whereas for the cullet ground to 3000 cm2/g, the reaction was severely delayed. In the course of one year, no negative impact of the alkali-silica reaction on the strength and microstructure of mortars and pastes was observed, however, a longer study needs to be conducted to verify the results. The research proves that waste glass cullet can be potentially used as a main component of Portland cements, with no adverse effects on the properties of the composites.

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The influence of four naturally occurring mineral additives (zeolite, diatomite, trass and bentonite) on the hydration and properties of cement pastes and mortars was investigated. The materials change the phase composition, heat of hydration (determined by calorimetry) and mechanical properties of composites. After 28 days, the amount of Ca(OH)2 was reduced by up to 23% and up to 35% more C-S-H was formed, as proved by TG measurements. Differences were observed in the kinetics of heat release, especially for 25% of the addition. In the calorimetric curves, an additional exothermic effect is observed, related to the alteration in the hydration of C3A in cement. From the point of view of beneficial influence on mechanical properties of mortars, the additives could be ranked as follows: bentonite < diatomite, zeolite < trass after 2 days and bentonite < diatomite < trass < zeolite after 28 days of curing. The highest compressive strength (58.5 MPa) was observed for the sample with a 10% addition of zeolite. Zeolite, trass, bentonite and diatomite are all pozzolanic materials; however, their activity varies to an extent due to the differences in their specific surface area and the content of the amorphous phase, responsible for the pozzolanic reaction.

Lime quartz samples in which ground quartz sand was gradually substituted with waste glass powder (GP) were obtained under hydrothermal conditions to determine the influence of GP addition on the microstructure (observed by SEM), phase composition (analyzed by XRD), and compressive strength of autoclaved building materials. An additional series containing analytical grade NaOH and no GP was formed to evaluate the effect of sodium ions on tobermorite formation and its impact on the mechanical properties of the samples. GP addition hindered the formation of tobermorite during autoclaving. Instead, a higher amount of an amorphous and semi-crystalline C–S–H phase formed, leading to the densification of the composite matrix. Nevertheless, tobermorite-like structures were found during both XRD and SEM analyses, proving that the presence of small amounts of Al3+ ions allowed, to an extent, for the stabilization of the phase despite the high sodium content. The compressive strength values indicate that the presence of alkali in the system and the resulting formation of additional portions of C–S–H have a beneficial influence on the mechanical properties of autoclaved composites. However, the effect fades with increasing glass powder content which, together with a slight expansion of the samples, suggests that at high sand substitution levels, an alkali–silica reaction takes place.

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