Most studies on chloride transport in alkali activated slag (AAS) in the past were carried out by using electrically accelerated test methods (such as ASTM C 1202 based on the total charge passed through the sample).Such test methods are known to be influenced significantly by the pore solution chemistry of concretes.As the chemistry of the pore solution of AAS is different from that of Portland cement (PC), electrically accelerated chloride transport test methods and their classification criterion developed for the PC systems may not be suitable to evaluate the chloride penetration resistance of the AAS systems.Instead, natural diffusion test might be more appropriate and scientifically sound.Although steady state natural diffusion test is usually preferred, it suffers from long test duration and, hence, is not practically acceptable.Instead, non-steady state chloride diffusion test has the advantages of its similarities to the real exposure environment, as well as much shorter test duration compared to the steady state chloride diffusion test.