Identification of phase composition of binders from alkali-activated mixtures of granulated blast furnace slag and fly ash

The prepared alkali-activated binders (AAB) and composites using suitable latent hydraulic raw materials represent an alternative to materials based on Portland cements. This paper deals with ways how to influence the functional parameters of AAB by setting up mixtures of granulated blast furnace slag (GBFS) and fly ash with selected chemical compositions. In this way the course of hydration process is modified and the phase composition of products of alkali activation is changed as well as their final properties. The amorphous character of the hydration products makes evaluation of the phase composition of hardened AAB difficult and significantly limits the number of experimental techniques suitable to characterise their phase composition. It was observed that measuring the pH of water extracts obtained from the alkali-activated mixtures can give supplementary information about the process of hardening of alkali-activated mixtures of GBFS and fly ash.Web of Science581887

Změna alkality během hydratace kompozitu z vysokopecní strusky a elektrárenského popílku

Resumé též českyThe alkalinity change of the alkaline activated blast furnace slag alone (a dose of 3 wt.% of Na2O) and of the composites containing up to 20 wt.% of the fly ash component is nearly the same and ranges from the pH value 11.43 after 3 days of hydration to the value of approx. 11.2 after 42 days of hydration. An increase of the fly ash content (up to 60 wt.%) decreases the internal pH values approx. by 0.2 at each respective time of hydration

Slags from steel production: Properties and their utilization

During steel production a considerable amount of slags is produced. In addition to its usual processing, as recycling in device for steel production and preparation of aggregates, it is also possible to apply less common slag processing ways. Depending on cooling mode of the steel slags these may show some binding properties. Geopolymer type binders can be prepared from the slag using alkali activators or the hydraulic properties of the dicalciumsilicate present in the slag can be induced by water. The paper summarizes present state of material utilisation of the steel slags with focus on emphasize of the possible sources of the slag volume instability. The infl uence of process of slag cooling on its phase composition is documented. It was also found that slags from real sources show diff erent parameters compared to samples obtained for laboratory examination.Web of Science52333332

Potential modification of hydration of alkali activated mixtures from granulated blast furnace slag and fly ash

Alkali activated binders (AAB) and composites from suitable latent hydraulic raw materials represent an alternative to materials based on Portland cements. The paper deals with possibilities to influence functional parameters of AAB by setting the mixtures of GBFS and fly ash to the selected chemical composition or by fly ash reactivity change effected by milling. In this way course of hydration process is modified, the alkali activation products phase composition is changed as well as their final characteristic. The amorphous character of the hydration products limits the evaluation of the composition during the massing phase. Part of the study is the search for possibilities of identifying the differences in composition and properties of specially drafted mixtures of original raw materials after their alkali activation.Web of Science56217616