Metakaolin as an Extender in South African Cement

Abstract

Metakaolin is a pozzolanic material obtained through thermal activation of kaolinite. It has several important advantages when used as an extender for Portland cement. This note describes the strength enhancement observed in mortars containing metakaolin additions between 10 and 30%. It was found that compressive strengths increase with increased curing times and depended strongly on the activation temperature used. Strength enhancements did not depend significantly on the concentration of metakaolin addition. Significant improvements in compressive strengths of cement mortars, up to 80% or more, was found in selected cases.