Investigation of the usage of stone powder waste cooked with boron minerals as a substitution and additive material in metakaolin-based geopolymer mortars

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Aktürk M., Topçu İ. B., Keskin Ü. S.

SELCUK UNIVERSITY JOURNAL OF ENGINEERING SCIENCES, vol.22, no.01, pp.6-15, 2023 (Peer-Reviewed Journal)


Although portland cement continues to be the most used binder material in the concrete industry today, due to the high energy requirement during the production of cement and the harmful effect of the CO₂ gas released on the atmosphere, some studies have been carried out for the production of alternative binder building materials to cement in recent years. In this study, geopolymer mortars that can be an alternative to cement were produced. In the production of mortar, metakaolin was used as binder, different percentages of baked stone dust waste, colemanite mineral, borax penta hydrate mineral and borax deca hydrate mineral were used as substitute material. In mortar production, 50% of 10 M sodium hydroxide (NaOH) and 50% of 2 module sodium silicate Na₂SiO₃ were used as alkali activators. Geopolymer mortars produced using a liquid/binder ratio of 1, a water/binder ratio of 0,60, and a sand/binder ratio of 2,25 were cured for 24 hours at room temperature and 60 ℃ curing conditions. When the dispersion values of the produced geopolymer mortars were examined, it was observed that the dispersion value increased with the increase of the replacement rate of the cooked stone powder waste substituted for the metakaolin as a binder, and the dispersion values increased with the increase of the substitution rate of colemanite, borax penta hydrate and borax deca hydrate substituted for the metakaolin. When the mechanical properties of the produced geopolymer mortars were examined, it was seen that the flexural and compressive strengths of 7 and 28 days at different curing temperatures for the metakaolin binder mortars got the best values among all mortars. As a result, metakaolin should be used as the main binder in the production of geopolymer mortar, It has been observed that up to 30% of baked stone dust wastes can be used as metakaolin replacement material in geopolymer mortars, especially in early strength conditions, and boron minerals cannot be used as a substitute material in geopolymer mortars in any way, and colemanite and borax pentahydrate minerals can be used up to 10% to 20% in especially early strength conditions. found to be used as an additive.