Concrete curing involves maintaining an adequate moisture level in the preliminary stages of concrete development to achieve its respective properties. However, practical limitations often make proper curing difficult. Consequently, researchers have explored the self-curing agents as a solution. These agents aim to decrease water evaporation from the concrete and enhance its water retention ability compared to traditional concrete. Self-curing concrete absorbs moisture from the atmosphere, promoting improved cement hydration and addressing issues caused by inadequate or absent curing, which can lead to unsatisfactory concrete properties. The present investigation involves the use of self-curing agent viz., polyethylene glycol (PEG) of molecular weight 400 (PEG 400) for dosages ranging between 0% to 2% by weight of cement added to mixing water and GGBS added 0% to 40% by replacing cement. The experimental program was planned as the following. Total 225 cubes, 225 cylinders, 225 prisms were cast which involves different dosages (0%, 0.5%, 1%, 1.5% and 2%) of self-curing agent PEG-400 and addition of GGBS (0%, 10%, 20%, 30%, and 40%) for three grades of concrete mixes (Mix M20, M40 and Mix 60), under different curing conditions (conventional and self-curing). Comparative studies were carried out for conventional concrete, supplementary cementitious concrete, self-curing concrete and supplementary cementitious self-curing concrete. Comparative studies were carried out for compressive strength, split tensile strength, flexural strength after 28 days of concrete. Supplementary cementitious Self-curing concrete is better in all aspects compared to conventional cured concrete.