Ceramics-Silikáty 61, (1) 65 - 73 (2017)

This study shows the results of an examination on the use of metakaolin (MK) as an additional cementing material to improve the mechanical properties and durability of cement paste and mortar. For MK replacement levels were employed in the study: 5%, 10%, 15% and 20% by weight of the Portland cement used. Three series of paste mixture were designed at three water-cementations materials (w/cm) ratios of 0.25, 0.30 and 0.40. The performance characteristics of the paste and mortars were evaluated by measuring compressive, drying shrinkage, and swelling. The sulfate resistance of the mortar was also examined in the present study. The results showed that the inclusion of MK exceptionally reduced the drying shrinkage strain and excellent performance of swelling, but increased the strengths of the cement paste in differing degrees, depending principally on the MK substitution levels, w/cm ratio, and age of testing. It was also affirmed that the MK provided an excellent improvement in resistance to the sulfate sodium (Na₂SO₄), especially for the high- level MK replacement.