The modulus of elasticity as per IS:456 – 1978 Ec=5700√Eck‌N∕mm2 The modulus of elasticity as per IS: 456:2000 Ec=5000√Eck‌N∕mm2 For M25 Ec=5700√Eck = 28,500 Mpa as per IS : 456 – 1978 Ec=5000√Eck = 25,000 Mpa as per IS : 456 : 2000