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The sulphate resistance of mortars made with fly ashes from co-burning bituminous coal and biomass
The results from investigations lead to the following preliminary conclusions: 1. The mortars made with fly ashes from co-burning bituminous coal and biomass (fly ashes CBFA) exhibited lower resistance to the action of sodium sulphate than the mortars made with fly ashes from bituminous coal combustion process (fly ashes CFA). 2. The inferior resistance to sulphate attack of the mortar incorporating fly ashes CBFA is attributed to its lower pozzolanic activity.3. Due to the lower pozzolanic activity, the incorporation of fly ashes CBFA resulted in increased permeability and reduced volume stability of mortars. 4. After one year of exposure to sulphate attack, the per cent of relative expansion of fly ashes CFA-16 mortar was lower than 0.2 and no visible signs of deterioration were observed. 5. For mortar incorporating fly ashes CBFA-32, visible scaling or spalling appeared after only six months of exposure to sulphate attack. The per cent expansion was more than 0.33 after one year of exposure to sulphate attack. 6. After 180 days of immersion in sulphate solution, the compressive strength of mortar made with fly ashes CFA- 16 was 8.5 per cent higher than that of moist-cured mortar, whereas that of mortar made with fly ashes CBFA- 32 mortar was 26.3 per cent lower. 7. In mortar made with fly ashes CBFA-32, large ettringite crystals were frequently found on the surface of the hydration products. The formation of large ettringite crystals on the surface of the hydration products as well as an increase in their size and shape generated a destructive pressure, which caused deterioration.
The sulphate resistance of mortars made with fly ashes from co-burning bituminous coal and biomass
The results from investigations lead to the following preliminary conclusions: 1. The mortars made with fly ashes from co-burning bituminous coal and biomass (fly ashes CBFA) exhibited lower resistance to the action of sodium sulphate than the mortars made with fly ashes from bituminous coal combustion process (fly ashes CFA). 2. The inferior resistance to sulphate attack of the mortar incorporating fly ashes CBFA is attributed to its lower pozzolanic activity.3. Due to the lower pozzolanic activity, the incorporation of fly ashes CBFA resulted in increased permeability and reduced volume stability of mortars. 4. After one year of exposure to sulphate attack, the per cent of relative expansion of fly ashes CFA-16 mortar was lower than 0.2 and no visible signs of deterioration were observed. 5. For mortar incorporating fly ashes CBFA-32, visible scaling or spalling appeared after only six months of exposure to sulphate attack. The per cent expansion was more than 0.33 after one year of exposure to sulphate attack. 6. After 180 days of immersion in sulphate solution, the compressive strength of mortar made with fly ashes CFA- 16 was 8.5 per cent higher than that of moist-cured mortar, whereas that of mortar made with fly ashes CBFA- 32 mortar was 26.3 per cent lower. 7. In mortar made with fly ashes CBFA-32, large ettringite crystals were frequently found on the surface of the hydration products. The formation of large ettringite crystals on the surface of the hydration products as well as an increase in their size and shape generated a destructive pressure, which caused deterioration.
The sulphate resistance of mortars made with fly ashes from co-burning bituminous coal and biomass
Tkaczewska, E. (author) / Malolepszy, J. (author)
Silicates Industriels ; 74 ; 163-170
2009
8 Seiten, 10 Bilder, 8 Tabellen, 21 Quellen
Article (Journal)
English
Notes on burning bituminous coal
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