Properties of mortars made by uncalcined FGD gypsum-fly ash-ground granulated blast furnace slag composite binder

Journal Article · Sun Jul 15 00:00:00 EDT 2012 · Waste Management

DOI:https://doi.org/10.1016/j.wasman.2012.02.014· OSTI ID:21612997

Kun, Ni; Jinmei, Li ^[1]

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1. Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China)

Highlights: Black-Right-Pointing-Pointer The mortar with uncalcined FGD gypsum has suitable workability. Black-Right-Pointing-Pointer The strength of mortar with uncalcined FGD gypsum is higher than that of mortar without uncalcined FGD gypsum. Black-Right-Pointing-Pointer The dry shrinkage of mortar with uncalcined FGD gypsum is lower than that of mortar without uncalcined FGD gypsum. Black-Right-Pointing-Pointer The leaching of sulfate ion of mortar is studied. - Abstract: A series of novel mortars were developed from composite binder of uncalcined FGD gypsum, fly ash (FA) and ground granulated blast furnace slag (GGBFS) for the good utilization of flue gas desulphurization (FGD) gypsum. At a fixed ratio (20%) of GGBFS to the composite binder, keeping consistency of the mortar between 9.5 and 10.0 cm, the properties of the composite mortar were studied. The results show that higher water/binder (W/B) is required to keep the consistency when increasing the percentage of FGD gypsum. No obvious influences of the W/B and content of FGD gypsum on the bleeding of paste were observed which keeps lower than 2% under all experimental conditions tried. The highest compressive and flexural strengths (ratio is 20% FGD gypsum, 20% GGBFS and 60% FA) are 22.6 and 4.3 MPa at 28 days, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that massive ettringite crystals and C-S-H gels exist in the hydration products. At 90 days the mortars with FGD gypsum is dramatically smaller drying shrinkage (563-938 micro strain) than that without FGD gypsum (about 2250 micro strain). The release of the SO{sub 4}{sup 2-} from the mortar was analyzed, indicating that the dissolution of sulfate increases with FGD gypsum. The concentration of SO{sub 4}{sup 2-} releasing from the mortar with 10% FGD gypsum is almost equal to that obtained from the mortar without FGD gypsum. The release of SO{sub 4}{sup 2-} from the mortar with 20% FGD gypsum is 9200 mg{center_dot}m{sup -2}, which is lower than that from the mortar with 95% cement clinker and 5% FGD gypsum.

• OSTI ID: 21612997
• Journal Information: Waste Management, Vol. 32, Issue 7; Other Information: DOI: 10.1016/j.wasman.2012.02.014; PII: S0956-053X(12)00074-8; Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0956-053X
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BLAST FURNACES
CEMENTS
CRYSTALS
DRYING
FLEXURAL STRENGTH
FLUE GAS
FLY ASH
GELS
GYPSUM
HYDRATION
LEACHING
MORTARS
PRESSURE RANGE MEGA PA
SCANNING ELECTRON MICROSCOPY
SHRINKAGE
SLAGS
SULFATES
X-RAY DIFFRACTION
AEROSOL WASTES
ASHES
BUILDING MATERIALS
COHERENT SCATTERING
COLLOIDS
COMBUSTION PRODUCTS
DIFFRACTION
DISPERSIONS
DISSOLUTION
ELECTRON MICROSCOPY
FURNACES
GASEOUS WASTES
MATERIALS
MECHANICAL PROPERTIES
MICROSCOPY
MINERALS
OXYGEN COMPOUNDS
PRESSURE RANGE
RESIDUES
SCATTERING
SEPARATION PROCESSES
SOLVATION
SULFATE MINERALS
SULFUR COMPOUNDS
WASTES