Evaluation of Sulfate Resistance of Calcined Dolomite Activated Ground Granulated Blast Furnace Slag

Abstract

Aggressive environments significantly influence the durability and serviceability of hardened cement and concrete. This paper presents an evaluation of the resistance of ground granulated blastfurnace slag (GGBS) activated with calcined dolomite, as a novel alkali activator, to 5% sodium sulfate attack and 5% magnesium sulfate attack. Two calcined dolomites, D800 and D1000, were prepared in the laboratory at 800 °C and 1000 °C respectively. The results demonstrated the good potential of using calcined dolomite activated slag in resisting sulfate attack. Immersion in Na 2 SO 4 (aq) led to an increase in strength in both the D800 (D800S) and the Portland cement CEM I 52.5N (PCS) activated slag, with a more pronounced effect in the former, while a decrease in the D1000 (D1000S) activated slag. On the Manuscript Click here to download Manuscript: Manuscript_revised.docx other hand, calcined dolomite activated slag had less strength loss than PCS after MgSO 4 attack. The products of sulfate attack and the deterioration processes are also analyzed by a range of tests including pH, weight change, corroded depth, XRD, TGA and SEM/EDS. After Na 2 SO 4 attack, the main product on D800S and D1000S was gypsum with a larger amount in the later. Gypsum, thaumasite and M-S-H were the main products of D800S and D1000S after MgSO 4 attack. The better resistance of D800S to sulfate attack was attributed to the absence of portlandite in the hydrated paste. On the other hand, the presence of portlandite in D1000S led to the inhomogeneous sulfate ions inward progression hence the severe deterioration of sample was observed.

Development of Eco-Friendly Mortars Produced with Blast Furnace Slag, Calcined Eggshell and Brick Waste: Mechanical Behavior and Microstructure Assessment

“…The works of Seungwon et al [37][38][39][40][41][42] were used to perform the microstructural analysis.…”

Development of reactive magnesia cement-based formulations with improved performance & sustainability

“…The thermal decomposition of dolomite can take place in two stages: (i) (Galı, Ayora et al 2001, Dí az, Torrecillas et al 2005, Barbhuiya 2011, Gu, Jin et al 2014, Yang, Ryu et al 2014, Liu, Wang et al 2015, Verian, Panchmatia et al 2015). Furthermore, dolomite has been used as an activator in alkali activated binders (Gu, Jin et al 2014, Gu, Jin et al 2016. When compared to the most common alkaline activators (e.g.…”