Aim of study was to verify the effect of temperature on the pozzolanic reactivity of thermally activated attapulgite and sepiolite samples. Activation temperatures were selected: 650, 700 and 750 °C for attapulgite and 800, 825 and 850 °C for sepiolite. Content of pozzolanic reactive SiO₂ and Al₂O₃ after thermal treatment and the amount of Ca(OH)₂ consumed in the pozzolanic reaction were measured. It should be noted that a higher activation temperature improves the reactivity of attapulgite and sepiolite. The upper limit for the increase in the pozzolanic reactivity of these materials is the formation of enstatite and the deactivation of silica. In addition to reactive decomposition products, series of minerals formed in the reactions of attapulgite and sepiolite with impurities present in them are also observed.

In the experiment, the aluminosilicate glasses with aluminum saturation index (ASI), defined as the Al₂O₃/(Na₂O+K₂O+2CaO), equal to 0.74, 1.72. 2.52, or 4.05 were synthesized. The spectroscopy tests (MIR and ²⁷Al MAS-NMR) confirm that in glass with ASI < 1, the aluminum ions occur in the [AlO₄]^5- only. In glasses with ASI > 1, the aluminum ions create mainly [AlO₄]^5-, but part of them occurs in the form of [AlO₆]^9-. The content of [AlO₆]^9- octahedrons increases successively for ASI from 1.72 to 4.05. Glass with ASI equal to 4.05 demonstrates the highest content of pozzolanic active Al₂O₃. Model ashes were prepared by mixing 70 wt.% of glass, 20 wt.% of synthetic mullite and 10 wt.% of SiO₂ as an equivalent of quartz. Then Portland cement CEM I 42.5R was milled together with 20 wt.% of each of model ashes to Blaine’s specific surface area of 4,200±50 cm² g^-1. It was found that the addition of ash with higher content of [AlO₆]^9- octahedrons in the structure of glass accelerates the hydration process of cement blend, which, in turn, positively affects its usable features (heat of hydration, initial setting time and compressive strength). According to the requirements of PN-EN 197-1:2012 standard, the introduction of ash with ASI coefficient equal to 4.05 gives cement blend of strength class of 52.5N. Cement blends with the ash of ASI value equal to 1.72 and 2.52 correspond to strength class of 32.5R, whereas the cement blend with the ash of ASI value equal to 0.74 does not achieve the minimum value of strength for any cement strength class. Results show that the change in chemical composition of fly ash glass and resulting from this diversified structure are essential from the point of view of hydration and properties of cement containing fly ashes in its composition.

The paper analyses the properties of Portland-composite cement CEM II/B-M (V-W) prepared by addition of mixture of siliceous and calcareous fly ashes – in percentage proportion of 20:0, 10:10, 20:10 or 15:15 – to Portland cement CEM I 42.5R. Blaine’s surface area of cements equalled 4000±100 cm2/g. Hydration heat, standard consistency, initial setting time, soundness and compressive strength were analysed in the paper. Partial replacement of siliceous fly ash with calcareous fly ash in cement gives a Portland-composite cement CEM II/B-M (V-W) of strength class 52.5N or even 52.5R, if the percentage proportion of siliceous to calcareous fly ash is 20:10.

The cement mixtures used in the studies were prepared by partial replacing of Portland cement CEM I 42.5R with a mixture of blast furnace slag and siliceous fly ash. The purpose of the study is to verify the properties of the ternary cements included in the PN-EN 197-5:2021 standard as CEM II/C-M and CEM VI cements. Their hydration heat, compressive strength, phase composition and microstructure were studied. The higher blast furnace slag content results in a greater reduction in the rate of hydration heat evolution and cumulative hydration heat evolved and lower and delayed effects related to Ca(OH)2 and alkalis presence. More blast furnace slag gives a cement mixture of the lower strength class according to the PN-EN 197-1:2012 standard. With the addition of 50 % blast furnace slag, none of the strength classes is achieved. Strength reduction may be due to the discontinuity in microstructure observed in SEM studies.

In the study, cement mixtures containing granulated blast furnace slag (GBFS) and siliceous fly ash (SFA) were tested, including those corresponding to special cements according to the PN-B-19707: 2013 standard. Measurements included the period of development of standard strength (up to 28 days) and concerned the compressive strength, linear changes and phase composition of cement mixtures. Furthermore, an evaluation of the microstructure of cement mortar was carried out by SEM. The mixture of composition CEM II/C-M (S-V) satisfies the requirements of the 32.5R or 32.5N strength class, whereas that of CEM VI (S-V) is of the 32.5N strength class, as opposed to stronger mixtures richer in Portland clinker.

Przedmiotem artykułu jest analiza właściwości zaczynu i zaprawy przygotowanych z mieszaniny cementu portlandzkiego CEM I 42,5R (CEM I) i mielonego wapienia (ML) w ilości 5%, 15%, 30%, 35%, 40% i 50% masy spoiwa. Badania właściwości zaczynów cementowych obejmowały ciepło hydratacji, konsystencję normową i początek czasu wiązania. W przypadku zapraw cementowych określono ich wytrzymałość na ściskanie. Ze wzrostem udziału wapienia następuje zmniejszenie szybkości wydzielania ciepła hydratacji. Cement zawierający do 35% ML wykazuje zbliżony czas początku wiązania w stosunku do cementu kontrolnego, natomiast przy udziale 40% i 50% ML czas początku wiązania ulega wyraźnemu skróceniu. Cement z dodatkiem 5% i 15% ML osiąga klasę wytrzymałości 42,5R, natomiast cement z dodatkiem 30% i 35% ML – jedynie klasę wytrzymałości 32,5N. Przy dodatku 40% i 50% ML cement nie spełnia wymagań normy PN-EN 197-1:2012 odnośnie klasy wytrzymałości.