STRENGTH AND CORROSION RESISTANCE OF METAKAOLIN-BASED GEOPOLYMER HYBRID MORTAR

Abstract

The utilization of metakaolin in the manufacture of geopolymers as a cement replacement material can be improve several of the physical, mechanical, and resistance properties of mortar in a corrosive environment. This paper presents the characteristics of metakaolin-based geopolymer cement mortar tested for setting time, compressive strength, and corrosion resistance. In this study, cement of the Portland Cement Composite type was added to the mortar mixture with 5% metakaolin forming a metakaolin-based geopolymer hybrid mortar. Three mortar mixes, namely MN (Normal Mortar), MK-100 (100% metakaolin), MK-95 (95% metakaolin and 5% cement), were cast and cured under ambient temperature until the testing days at 3, 7, and 28 days respectively. The alkaline activator ratio (Na2SiO3/NaOH) of 2, water to binder ratio of 0.8 was selected to form metakaolin-based geopolymer mortar specimens and the water binder ratio of 0.5 was selected to mix the cement mortar (MN). The results show that MK-100 and MK-95 exhibited a higher compressive strength than the cement mortar (MN) on all of the testing days. However, MK-95 showed a better performance in terms of corrosion resistance with a lower corrosion rate density compared to the MN and MK-100 mortar specimens. This indicates that the metakaolin-based geopolymer hybrid mortar with a 5% cement mixture can be applied on site as a repair and coating material, particularly for construction in a corrosive environment.