Evaluation of the Pozzolanic Activity of Metakaolin, Glass Powder and Silica Powder for Use in Cementitious Mortars

The objective of this study is to evaluate the pozzolanic activity of metakaolin, glass powder and silica powder for use in cementitious mortars. Thus, metakaolin was produced by calcination at 700 °C of a clay soil from Burkina composed of kaolinite (62 wt.%), quartz (30 wt.%) and goethite (6 wt.%). Glass powder consists of amorphous silica and silica powder essentially contains quartz. The chemical characterization of materials showed that the metakaolin and the silica powder belong to the category of type F pozzolans while the silica powder would be type N. The lime saturation test reveals low kinetics of lime fixation by the silica powder. On the other hand, the rate of lime fixation by metakaolin and glass powder increases with treatment time. The pozzolanic index of metakaolin and glass powder at 28 and 90 days is higher than the minimum value of 75% required by the ASTM C618 standard. The presence of metakaolin and glass powder within the cement matrix improves the compressive strength of the resulting mortars due to their good pozzolanic reactivity inducing the formation of calcium silicates hydrated (CSH). Metakaolin and glass powder are therefore suitable for replacing cement in the production of mortars in the construction field.