M20 concrete is a pretty standard mix in construction because it's strong but still easy to work with. The mix is usually 1 part cement, 1.5 parts sand, and 3 parts gravel. If you let it cure for about a month, it should have a compressive strength of 20 MPa.
You can use M20 concrete for things like houses, sidewalks, and those precast concrete pieces. Because it can be used in many ways, builders really like it. Just remember to mix and cure it right so it gets strong like it's supposed to.
If you want to know more about which of our cements work best for M20 concrete, check out our product page.