In this analysis, the goal is to determine the durability quality such as water absorption, sorptivity and the acid attack of flyash metakaolin based SCGC and to study its microstructural behaviour with varying NaOH concentrations like 8M, 10M and 12M. In this investigation, fly-ash was swapped using metakaolin to the order of 0%, 10%, 20%, and 30% by mass. Fluids to binder ratio of 0.47 by mass and constant binding content of 400 kg/m³ were kept constant for all the molarities. S.P dosage of 3% was kept consistent for all the mixes from M1 to M12 and the water content was changed accordingly. The samples were moulded and cured for 24 hours in a 70 °C oven, after which climatic healing was backed until the testing days. Water absorption and sorptiveness increased when metakaolin content rose compared to the control mix, regardless of molarity. The greater molarity was attributed to the tougher structure, which prevented absorption. When compared to other replacement levels, the water absorption value for 10% replacement of fly-ash by metakaolin after 28 days was the lowest. And the strength loss was extremely low when preserved at 5% concentration in the sulphuric acid media. Regardless of molarity, a 10% substitution of metakaolin exhibited greater resistance to sulfuric acid attack. As a result, this could be a better alternative to traditional OPC concrete in terms of structural applications, as well as CO₂ reductions.