Abstract The concept of using recycled aggregate for making concrete is slowly but definitely gaining popularity. Research is in progress to make this technology feasible. The results of the present investigation, reported here, is one such attempt. The basic objective of the present study, is to attain acceptable quality of concrete with maximum utilisation of recycled aggregate in place of natural aggregate. In this paper, the term “Replacement ratio” is introduced and is defined as ratio of recycled coarse aggregate to total coarse aggregate in a concrete mix. Concrete mix cases with replacement ratio of 0, 0.25, 0.50, 0.75 and 1.00 have been considered for the present investigation, to evaluate its behaviour both in fresh and hardened states. The above study has been performed for three mix cases, with water-cement ratio of 0.57, 0.50 and 0.43 respectively. Empirical relations have been proposed, to estimate the moduli of elasticity and of rupture of concrete with any replacement ratio. A maximum value of the replacement ratio is suggested, keeping in view, the overall behaviour of concrete and the basic objective of this investigation.