Compressive strength development of mortar from partially cement substitution by limestone powder and metakaolin

The aim of this study is to investigate the mechanism that has an effect on compressive strength development of mortar from partially substitution cement by combination of limestone powder and metakaolin. The percentage of binding material between limestone powder and metakaolin is 45% by dry weight of cement. The strength was tested by mortar and the microstructure determination was done by paste. The results show that 45% cement replacement by 15% limestone powder and 30% metakaolin with 1% PCEs (B45S 1:2) have the compressive strength reached almost the same with mortar reference at 28 days with 97% relative. The results also show that the cement replacement by limestone powder and metakaolin leads to the synergetic reaction between aluminate and carbonate. It can be observed by more forming supplementary AFm phases (hemicarboaluminate and monocarboaluminate phases). That is the main mechanism which develop the compressive strength of ternary blend mortar. Moreover, it has limitation of synergetic reaction cause of impurity of metakaolin and it make the compressive strength not well as an expected.