ACTIVATION OF METAKAOLIN BY CaO And CaSO₄ ANHYDRITE II

Abstract

The paper presented deals with the activation of metakaolin enabling the preparation of a new hydraulic binder. Activation of metakaolin is carried out using calcium oxide or hydroxide and gypsum or CaSO₄ in the form of anhydrite II. CaO and CaSO₄ anhydrite II were found to be more effective activators of metakaolin compared to Ca(OH)₂ and CaSO₄.2H₂O. The binding phase is represented here by an amorphous C-A-S-H phase accompanied with a C-S-H phase indicating similarity with Roman cement. Several crystalline hydrating products are present in the binder with ettringite being the major phase, and CaCO₃, Ca(OH)₂ and CaSO₄.2H₂O constituting its minor phases. In its composition, the binder, which is prepared synthetically, agrees with that of hydrated FBC ashes, and was found to be stable over a period of 2.8 years achieving strengths comparable to those of Portland cement.

Keywords

• metakaolin
• activation
• hydraulic binder
• roman cement
• caso₄ anhydrite ii