The impact of alkali content on the properties of Limestone Calcined Clay Cement (LC3) was investigated in this study. KOH was added in order to increase the alkali content of the blended cements from 0.44% Na2Oeq to 1.21% Na2Oeq. The increase of alkali accelerates the degree of clinker hydration at 1 day but it slows down for later ages. Moreover, increasing alkalinity enhances the formation of carboaluminate phases at the early ages but the highest alkali content shows the smallest amount these phases at the later ages. The porosity decreases with increasing the percentage of alkali at 3 days but it is opposite at 28 days. The compressive strength can be boosted at early ages but there is loss gain strength at the later age for LC3-65 (2:1)-1.21% Na2Oeq.