Activation of Blast Furnace Slag by Some Inorganic Materials


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Title: Activation of Blast Furnace Slag by Some Inorganic Materials

Author(s): J. Metso and E. Kajaus

Publication: Special Publication

Volume: 79


Appears on pages(s): 1059-1074

Keywords: accelerating agents; blast furna gypsum; pel ce slag; compressive lets; portland cement a e-strength relation* strength; fly ash; gra s. nulating;

Date: 5/1/1983

The activation of merwinite-gehlenite type blast furnace slag was studied using ordinary Portland cement clinker, Ca(OH) CaS04 . 2 H20, NaOH, Na2Si03, Na2C03, fly ash, phosphogypsum, f I admixture, etc. The blast furnace slag used in this investigation was either granulated slag or pelletized slag. The spe ific sur- 5 face area of the granulated slag was 270 m2/kg or 400 m /kg and was 500 m2/kg when used with F-admixture. Sodium hydroxides, phospho-gypsum + NaOH, Na2C03 + NaOH and fly ash + NaOH were good activa-tors. Pelletized slag was activated well with strong bases. The pelletized slag needed higher concentration of NaOH than granulated slag. Fresh granulated and pelletized slag with a specific surface of about 300 m2/kg or higher could be self-activated and gave a compressive strength of 20 MPa at 28 days. The aged,ground granulated and pelletized blast furnace slag, however, did not harden without an activator. With both slags, at a slag content of 300 kgjm3, high compressive strength was obtained with F-admixture. The compressive strength at early ages was comparable to that of normal concrete, when the binding agent was ordinary Portland cement.