The present study deals with identifying water, chloride and sulphate penetration characteristics of ambient cured graded GPC and the same is compared with conventional concrete. Geopolymer concrete is produced by adding source materials rich in silica and alumina such as Fly Ash (FA) and Ground Granulated Blast Furnace Slag (GGBS) with strong alkaline solutions, such as sodium hydroxide (NaOH) and sodium silicate (Na2 SiO3). Incorporation of GGBS in Fly ash based Geopolymer Concrete (GPC) shows promising results in terms of fresh and hardened concrete properties under ambient cured conditions. Grading GPC is used in the present work as the grade identification of concrete are very important in structural applications. Water penetration characteristics and chemical exposure of concrete have been a contentious issue because of presence of capillary pores and pore structure. Refinement in pore structure is possible with addition of cementitious materials to concrete. Since GPC, i.e., no cement concrete is composed of polymerization of pozzolanic materials under high alkaline medium, durability studies need to be studied rigorously for practical applications. Water penetration properties of GPC is assessed through water absorption test, sorptivity test and permeability test. Chloride penetration characteristics also estimated using Rapid Chloride Penetration Test (RCPT). Aggressive environment action on GPC is measured by exposing specimen to MgSO4 and Na2SO4 solution. Sulphate exposure on GPC is evaluated through physical observation, changes in weight, strength and elongations. The results of investigation indicated that compact pore structure of higher-grade GPC has similar penetration characteristics as that of conventional concrete. Further, it is noticed that chloride permeability decreases with curing age and with increase in grade of GPC. The same is further confirmed through formation of Friedel’s salt in microstructure of GPC observed through Scanned Electron Microscope (SEM) and Energy Dispersive X ray Spectrum (EDX). Microstructure of higher grade of GPC shows slight traces of ettringite, giving a clear indication of better resistance to sulphate attack compared to conventional concrete.