The water-cement ratio is one of the major factor for strength and curing is another major factor for strength.
The water-cement ratio is not sufficient for concrete to get strength without curing.
When cement and water cames in contact hydration reaction starts. Which emits heat. If you don’t cure than crack on surface will appears. And ultimately looses it’s strength.
To prove my point point, I like share data of experiment of compressive strength of concret cube. Which I have done in material testing lab.
So here it is.
Cube casting @ 28/8/2019
Fck= 25 KN/M3 , Targeted =31.6KN/M3
Sample 1(Nominal) 3days -16.32KN/M3
Sample 2(Nominal) 7days -20.6 KN/M3 , Peak=464.5KN.
Sample 3(Nominal) 28days-27.8 KN/M3
Sample 1(Ungraded) 7days -22.56 KN/M3,
Sample 2(Ungraded) 28days – 26.18KN/M3
Sample 1 (plasticizer) 28days –
As you can see my cubes were failed at 28days. Because of my one mistake. Me and my group members forget to check the water level of curing tank. The 1/4 of the cube was emerged in water.
Hence, curing plays important role to get strength.
So, do curing properly to get desired strength.
Hope this answer will make you understand the importance of curing.