Hydration mechanisms of super sulphated slag cement

Gruskovnjak, A.; Lothenbach, Barbara; Winnefeld, Frank; Figi, Renato; Ko, Suz-Chung; Adler, Michael; Mäder, Urs

doi:10.1016/j.cemconres.2008.03.004

Cited by 228 publications

(118 citation statements)

References 16 publications

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“…The early formation of C-S-H was also evidenced by the continuous weight losses in the range at 130-640 °C (8), such losses were higher for the SC 80-10-10, which suggests an intense reaction of the PC that was in greater proportion than in SC 80-15-5. The decomposition at 650-700 °C could be attributed to the decomposition of CaCO 3 (5,19) that was also identified by XRD.…”

Section: Early Hydrationmentioning

confidence: 99%

“…The SC have hydraulic character and consist of 80-85% BFS, 10-15% of a source of calcium sulphate and an alkaline media that can be PC (3), hydrated lime (4) or other compounds. The main hydration products are reported as ettringite and calcium silicate hydrates (C-S-H) (5)(6)(7). Among the advantages of SC over PC are their resistance to the aggressive attack of sulphates and the low heat of hydration (8).…”

Section: Introductionmentioning

confidence: 99%

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Early and late hydration of supersulphated cements of blast furnace slag with fluorgypsum

Bazaldúa-Medellín¹,

Fuentes²,

Gorokhovsky³

et al. 2015

Mater. construcc.

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ABSTRACT:The hydration, strength development and composition of hydration products of supersulphated cements were characterized from the first 48 hours up to 360 days. Two compositions of 80% Blast furnace slag, 10-15% Fluorgypsum and 10-5% Portland cement were cured in dry and wet conditions. The main hydration products were ettringite and C-S-H since the first hours and up to 360 days as evidenced by X-ray diffraction, thermal analysis and electron microscopy. The strength was favored by higher fluorgypsum contents and lower Portland cement contents. These cements generated heats of hydration of 40-57 KJ/Kg after 28 hours, which are lower than portland cement. RESUMEN: Hidratación temprana y tardía de cementos supersulfatados de escoria de alto horno con fluoryeso.Se realizó la caracterización de la hidratación, desarrollo de resistencia y la composición de los productos de hidratación de los cementos supersulfatados durante las primeras 48 horas y hasta 360 días. Se estudiaron dos composiciones de 80% de Escoria de alto horno, 10-15% de Fluoryeso y 10-5% de Cemento portland, se curaron en condiciones secas y húmedas. Los principales productos de hidratación fueron etringita y C-S-H desde las primeras horas y hasta 360 días, como se evidenció por difracción de rayos X, análisis térmico y microscopía electrónica de barrido. La resistencia se favoreció con mayor contenido de fluoryeso y bajos contenidos de cemento portland. Estos cementos generaron calores de hidratación de 40-57 KJ/Kg después de 28 horas, los cuales resultan más bajos que los generados por el cemento portland.

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Section: Early Hydrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Early and late hydration of supersulphated cements of blast furnace slag with fluorgypsum

Bazaldúa-Medellín¹,

Fuentes²,

Gorokhovsky³

et al. 2015

Mater. construcc.

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“…The electrochemical data are strongly influenced by the presence of sulfide. At later ages of the evolution of slag-containing cements, oxidation from HS -to higher sulfur oxidation states, up to and including sulfate, and the uptake of these species by solids, are very important [13,54,56]. Due to these simultaneous processes of release and consumption, the HS -concentration is not directly correlated with the degree of slag dissolution in a more mature binder system.…”

Section: Polarization Curvesmentioning

confidence: 99%

Influence of slag composition on the stability of steel in alkali-activated cementitious materials

et al. 2017

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Among the minor elements found in metallurgical slags, sulfur and manganese can potentially influence the corrosion process of steel embedded in alkali-activated slag cements, as both are redox-sensitive. Particularly, it is possible that these could significantly influence the corrosion process of the steel. Two types of alkali-activated slag mortars were prepared in this study: 100% blast furnace slag and a modified slag blend (90% blast furnace slag ? 10% silicomanganese slag), both activated with sodium silicate. These mortars were designed with the aim of determining the influence of varying the redox potential on the stability of steel passivation under exposure to alkaline and alkaline chloride-rich solutions. Both types of mortars presented highly negative corrosion potentials and high current density values in the presence of chloride. The steel bars extracted from mortar samples after exposure do not show evident pits or corrosion product layers, indicating that the presence of sulfides reduces the redox potential of the pore solution of slag mortars, but enables the steel to remain in an apparently passive state. The presence of a high amount of MnO in the slag does not significantly affect the corrosion process of steel under the conditions tested. Mass transport through the mortar to the metal is impeded with increasing exposure time; this is associated with refinement of the pore network as the slag continued to react while the samples were immersed.

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“…The addition of a Casulfate source results in the precipitation of ettringite as major product [31]. Because of the low solubility of ettringite, the Al activity in the pore solution is much reduced and the slag dissolution rate is enhanced.…”

Section: Understanding Scms: Recent Insights Into Reactivitymentioning

confidence: 99%

Assessing, Understanding and Unlocking Supplementary Cementitious Materials

Snellings

2016

RILEM Tech Lett

205

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The partial replacement of Portland clinker by supplementary cementitious materials (SCM) is one of the most popular and effective measures to reduce both costs and CO2 emissions related to cement production. An estimated 800 Mt/y of blast furnace slags, fly ashes and other materials are currently being used as SCM, but still the cement industry accounts for 5-8% of global CO2 emissions. If no further actions are taken, by the year 2050 this share might even rise beyond 25%. There is thus a clear challenge as to how emissions will be kept at bay and sustainability targets set by international commitments and policy documents will be met. Part of the solution will be a further roll-out of blended cements in which SCMs constitute the main part of the binder to which activators such as Portland cement are added. Since supply concerns are being raised for conventional high-quality SCMs it is clear that new materials and beneficiation technologies will need to step in to achieve further progress. This paper presents opportunities and challenges for new SCMs and demonstrates how advances towards more powerful and reliable characterisation techniques help to better understand and exploit SCM reactivity.

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Hydration mechanisms of super sulphated slag cement

Cited by 228 publications

References 16 publications

Early and late hydration of supersulphated cements of blast furnace slag with fluorgypsum

Early and late hydration of supersulphated cements of blast furnace slag with fluorgypsum

Influence of slag composition on the stability of steel in alkali-activated cementitious materials

Assessing, Understanding and Unlocking Supplementary Cementitious Materials

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