Durability of Concrete Made With Alkali-Activated Slag

Byfors, Kajsa; Klingstedt, Gunnar; Lehtonen, V.; Pyy, Hannu; Rombén, Lars

doi:10.14359/1827

Cited by 10 publications

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“…The carbonation rates of alkali-activated slag under service conditions are relatively slow and are comparable to PC [ 10 , 11 , 12 ]. Several other works have reported higher carbonation in AAS compared to PC as measured from accelerated carbonation tests [ 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Puertas et al [ 20 ] reported a 3- and 10-fold higher carbonation depth in slag activated with NaOH and waterglass, respectively, compared to PC under saturated CO 2 conditions.…”

Section: Introductionmentioning

confidence: 99%

Supercritical CO2-Induced Evolution of Alkali-Activated Slag Cements

et al. 2022

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The phase changes in alkali-activated slag samples when exposed to supercritical carbonation were evaluated. Ground granulated blast furnace slag was activated with five different activators. The NaOH, Na2SiO3, CaO, Na2SO4, and MgO were used as activators. C-S-H is identified as the main reaction product in all samples along with other minor reaction products. The X-ray diffractograms showed the complete decalcification of C-S-H and the formation of CaCO3 polymorphs such as calcite, aragonite, and vaterite. The thermal decomposition of carbonated samples indicates a broader range of CO2 decomposition. Formation of highly cross-linked aluminosilicate gel and a reduction in unreacted slag content upon carbonation is observed through 29Si and 27Al NMR spectroscopy. The observations indicate complete decalcification of C-S-H with formation of highly cross-linked aluminosilicates upon sCO2 carbonation. A 20–30% CO2 consumption per reacted slag under supercritical conditions is observed.

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